The Tor Browser: media/libvpx/vp8/encoder/firstpass.c@b8a032363ba2 (annotated)

media/libvpx/vp8/encoder/firstpass.c@b8a032363ba2 (annotated)

media/libvpx/vp8/encoder/firstpass.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /*
  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include <math.h>
 #include <limits.h>
 #include <stdio.h>
 #include "./vpx_scale_rtcd.h"
 #include "block.h"
 #include "onyx_int.h"
 #include "vp8/common/variance.h"
 #include "encodeintra.h"
 #include "vp8/common/setupintrarecon.h"
 #include "vp8/common/systemdependent.h"
 #include "mcomp.h"
 #include "firstpass.h"
 #include "vpx_scale/vpx_scale.h"
 #include "encodemb.h"
 #include "vp8/common/extend.h"
 #include "vpx_mem/vpx_mem.h"
 #include "vp8/common/swapyv12buffer.h"
 #include "rdopt.h"
 #include "vp8/common/quant_common.h"
 #include "encodemv.h"
 #include "encodeframe.h"
 /* #define OUTPUT_FPF 1 */
 extern void vp8cx_frame_init_quantizer(VP8_COMP *cpi);
 extern void vp8_set_mbmode_and_mvs(MACROBLOCK *x, MB_PREDICTION_MODE mb, int_mv *mv);
 extern void vp8_alloc_compressor_data(VP8_COMP *cpi);
 #define GFQ_ADJUSTMENT vp8_gf_boost_qadjustment[Q]
 extern int vp8_kf_boost_qadjustment[QINDEX_RANGE];
 extern const int vp8_gf_boost_qadjustment[QINDEX_RANGE];
 #define IIFACTOR   1.5
 #define IIKFACTOR1 1.40
 #define IIKFACTOR2 1.5
 #define RMAX       14.0
 #define GF_RMAX    48.0
 #define KF_MB_INTRA_MIN 300
 #define GF_MB_INTRA_MIN 200
 #define DOUBLE_DIVIDE_CHECK(X) ((X)<0?(X)-.000001:(X)+.000001)
 #define POW1 (double)cpi->oxcf.two_pass_vbrbias/100.0
 #define POW2 (double)cpi->oxcf.two_pass_vbrbias/100.0
 #define NEW_BOOST 1
 static int vscale_lookup[7] = {0, 1, 1, 2, 2, 3, 3};
 static int hscale_lookup[7] = {0, 0, 1, 1, 2, 2, 3};
 static const int cq_level[QINDEX_RANGE] =
 {
 ,0,1,1,2,3,3,4,4,5,6,6,7,8,8,9,
 ,10,11,11,12,13,13,14,15,15,16,17,17,18,19,20,
 ,21,22,22,23,24,24,25,26,27,27,28,29,30,30,31,
 ,33,33,34,35,36,36,37,38,39,39,40,41,42,42,43,
 ,45,46,46,47,48,49,50,50,51,52,53,54,55,55,56,
 ,58,59,60,60,61,62,63,64,65,66,67,67,68,69,70,
 ,72,73,74,75,75,76,77,78,79,80,81,82,83,84,85,
 ,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100
 };
 static void find_next_key_frame(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame);
 /* Resets the first pass file to the given position using a relative seek
  * from the current position
  */
 static void reset_fpf_position(VP8_COMP *cpi, FIRSTPASS_STATS *Position)
 {
     cpi->twopass.stats_in = Position;
 }
 static int lookup_next_frame_stats(VP8_COMP *cpi, FIRSTPASS_STATS *next_frame)
 {
     if (cpi->twopass.stats_in >= cpi->twopass.stats_in_end)
         return EOF;
     *next_frame = *cpi->twopass.stats_in;
     return 1;
 }
 /* Read frame stats at an offset from the current position */
 static int read_frame_stats( VP8_COMP *cpi,
                              FIRSTPASS_STATS *frame_stats,
                              int offset )
 {
     FIRSTPASS_STATS * fps_ptr = cpi->twopass.stats_in;
     /* Check legality of offset */
     if ( offset >= 0 )
     {
         if ( &fps_ptr[offset] >= cpi->twopass.stats_in_end )
              return EOF;
     }
     else if ( offset < 0 )
     {
         if ( &fps_ptr[offset] < cpi->twopass.stats_in_start )
              return EOF;
     }
     *frame_stats = fps_ptr[offset];
     return 1;
 }
 static int input_stats(VP8_COMP *cpi, FIRSTPASS_STATS *fps)
 {
     if (cpi->twopass.stats_in >= cpi->twopass.stats_in_end)
         return EOF;
     *fps = *cpi->twopass.stats_in;
     cpi->twopass.stats_in =
          (void*)((char *)cpi->twopass.stats_in + sizeof(FIRSTPASS_STATS));
     return 1;
 }
 static void output_stats(const VP8_COMP            *cpi,
                          struct vpx_codec_pkt_list *pktlist,
                          FIRSTPASS_STATS            *stats)
 {
     struct vpx_codec_cx_pkt pkt;
     pkt.kind = VPX_CODEC_STATS_PKT;
     pkt.data.twopass_stats.buf = stats;
     pkt.data.twopass_stats.sz = sizeof(FIRSTPASS_STATS);
     vpx_codec_pkt_list_add(pktlist, &pkt);
 /* TEMP debug code */
 #if OUTPUT_FPF
     {
         FILE *fpfile;
         fpfile = fopen("firstpass.stt", "a");
         fprintf(fpfile, "%12.0f %12.0f %12.0f %12.4f %12.4f %12.4f %12.4f"
                 " %12.4f %12.4f %12.4f %12.4f %12.4f %12.4f %12.4f %12.4f"
                 " %12.0f %12.0f %12.4f\n",
                 stats->frame,
                 stats->intra_error,
                 stats->coded_error,
                 stats->ssim_weighted_pred_err,
                 stats->pcnt_inter,
                 stats->pcnt_motion,
                 stats->pcnt_second_ref,
                 stats->pcnt_neutral,
                 stats->MVr,
                 stats->mvr_abs,
                 stats->MVc,
                 stats->mvc_abs,
                 stats->MVrv,
                 stats->MVcv,
                 stats->mv_in_out_count,
                 stats->new_mv_count,
                 stats->count,
                 stats->duration);
         fclose(fpfile);
     }
 #endif
 }
 static void zero_stats(FIRSTPASS_STATS *section)
 {
     section->frame      = 0.0;
     section->intra_error = 0.0;
     section->coded_error = 0.0;
     section->ssim_weighted_pred_err = 0.0;
     section->pcnt_inter  = 0.0;
     section->pcnt_motion  = 0.0;
     section->pcnt_second_ref = 0.0;
     section->pcnt_neutral = 0.0;
     section->MVr        = 0.0;
     section->mvr_abs     = 0.0;
     section->MVc        = 0.0;
     section->mvc_abs     = 0.0;
     section->MVrv       = 0.0;
     section->MVcv       = 0.0;
     section->mv_in_out_count  = 0.0;
     section->new_mv_count = 0.0;
     section->count      = 0.0;
     section->duration   = 1.0;
 }
 static void accumulate_stats(FIRSTPASS_STATS *section, FIRSTPASS_STATS *frame)
 {
     section->frame += frame->frame;
     section->intra_error += frame->intra_error;
     section->coded_error += frame->coded_error;
     section->ssim_weighted_pred_err += frame->ssim_weighted_pred_err;
     section->pcnt_inter  += frame->pcnt_inter;
     section->pcnt_motion += frame->pcnt_motion;
     section->pcnt_second_ref += frame->pcnt_second_ref;
     section->pcnt_neutral += frame->pcnt_neutral;
     section->MVr        += frame->MVr;
     section->mvr_abs     += frame->mvr_abs;
     section->MVc        += frame->MVc;
     section->mvc_abs     += frame->mvc_abs;
     section->MVrv       += frame->MVrv;
     section->MVcv       += frame->MVcv;
     section->mv_in_out_count  += frame->mv_in_out_count;
     section->new_mv_count += frame->new_mv_count;
     section->count      += frame->count;
     section->duration   += frame->duration;
 }
 static void subtract_stats(FIRSTPASS_STATS *section, FIRSTPASS_STATS *frame)
 {
     section->frame -= frame->frame;
     section->intra_error -= frame->intra_error;
     section->coded_error -= frame->coded_error;
     section->ssim_weighted_pred_err -= frame->ssim_weighted_pred_err;
     section->pcnt_inter  -= frame->pcnt_inter;
     section->pcnt_motion -= frame->pcnt_motion;
     section->pcnt_second_ref -= frame->pcnt_second_ref;
     section->pcnt_neutral -= frame->pcnt_neutral;
     section->MVr        -= frame->MVr;
     section->mvr_abs     -= frame->mvr_abs;
     section->MVc        -= frame->MVc;
     section->mvc_abs     -= frame->mvc_abs;
     section->MVrv       -= frame->MVrv;
     section->MVcv       -= frame->MVcv;
     section->mv_in_out_count  -= frame->mv_in_out_count;
     section->new_mv_count -= frame->new_mv_count;
     section->count      -= frame->count;
     section->duration   -= frame->duration;
 }
 static void avg_stats(FIRSTPASS_STATS *section)
 {
     if (section->count < 1.0)
         return;
     section->intra_error /= section->count;
     section->coded_error /= section->count;
     section->ssim_weighted_pred_err /= section->count;
     section->pcnt_inter  /= section->count;
     section->pcnt_second_ref /= section->count;
     section->pcnt_neutral /= section->count;
     section->pcnt_motion /= section->count;
     section->MVr        /= section->count;
     section->mvr_abs     /= section->count;
     section->MVc        /= section->count;
     section->mvc_abs     /= section->count;
     section->MVrv       /= section->count;
     section->MVcv       /= section->count;
     section->mv_in_out_count   /= section->count;
     section->duration   /= section->count;
 }
 /* Calculate a modified Error used in distributing bits between easier
  * and harder frames
  */
 static double calculate_modified_err(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
 {
     double av_err = ( cpi->twopass.total_stats.ssim_weighted_pred_err /
                       cpi->twopass.total_stats.count );
     double this_err = this_frame->ssim_weighted_pred_err;
     double modified_err;
     if (this_err > av_err)
         modified_err = av_err * pow((this_err / DOUBLE_DIVIDE_CHECK(av_err)), POW1);
     else
         modified_err = av_err * pow((this_err / DOUBLE_DIVIDE_CHECK(av_err)), POW2);
     return modified_err;
 }
 static const double weight_table[256] = {
 .020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000,
 .020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000,
 .020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000,
 .020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000,
 .020000, 0.031250, 0.062500, 0.093750, 0.125000, 0.156250, 0.187500, 0.218750,
 .250000, 0.281250, 0.312500, 0.343750, 0.375000, 0.406250, 0.437500, 0.468750,
 .500000, 0.531250, 0.562500, 0.593750, 0.625000, 0.656250, 0.687500, 0.718750,
 .750000, 0.781250, 0.812500, 0.843750, 0.875000, 0.906250, 0.937500, 0.968750,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 .000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000
 };
 static double simple_weight(YV12_BUFFER_CONFIG *source)
 {
     int i, j;
     unsigned char *src = source->y_buffer;
     double sum_weights = 0.0;
     /* Loop throught the Y plane raw examining levels and creating a weight
      * for the image
      */
     i = source->y_height;
     do
     {
         j = source->y_width;
         do
         {
             sum_weights += weight_table[ *src];
             src++;
         }while(--j);
         src -= source->y_width;
         src += source->y_stride;
     }while(--i);
     sum_weights /= (source->y_height * source->y_width);
     return sum_weights;
 }
 /* This function returns the current per frame maximum bitrate target */
 static int frame_max_bits(VP8_COMP *cpi)
 {
     /* Max allocation for a single frame based on the max section guidelines
      * passed in and how many bits are left
      */
     int max_bits;
     /* For CBR we need to also consider buffer fullness.
      * If we are running below the optimal level then we need to gradually
      * tighten up on max_bits.
      */
     if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
     {
         double buffer_fullness_ratio = (double)cpi->buffer_level / DOUBLE_DIVIDE_CHECK((double)cpi->oxcf.optimal_buffer_level);
         /* For CBR base this on the target average bits per frame plus the
          * maximum sedction rate passed in by the user
          */
         max_bits = (int)(cpi->av_per_frame_bandwidth * ((double)cpi->oxcf.two_pass_vbrmax_section / 100.0));
         /* If our buffer is below the optimum level */
         if (buffer_fullness_ratio < 1.0)
         {
             /* The lower of max_bits / 4 or cpi->av_per_frame_bandwidth / 4. */
             int min_max_bits = ((cpi->av_per_frame_bandwidth >> 2) < (max_bits >> 2)) ? cpi->av_per_frame_bandwidth >> 2 : max_bits >> 2;
             max_bits = (int)(max_bits * buffer_fullness_ratio);
             /* Lowest value we will set ... which should allow the buffer to
              * refill.
              */
             if (max_bits < min_max_bits)
                 max_bits = min_max_bits;
         }
     }
     /* VBR */
     else
     {
         /* For VBR base this on the bits and frames left plus the
          * two_pass_vbrmax_section rate passed in by the user
          */
         max_bits = (int)(((double)cpi->twopass.bits_left / (cpi->twopass.total_stats.count - (double)cpi->common.current_video_frame)) * ((double)cpi->oxcf.two_pass_vbrmax_section / 100.0));
     }
     /* Trap case where we are out of bits */
     if (max_bits < 0)
         max_bits = 0;
     return max_bits;
 }
 void vp8_init_first_pass(VP8_COMP *cpi)
 {
     zero_stats(&cpi->twopass.total_stats);
 }
 void vp8_end_first_pass(VP8_COMP *cpi)
 {
     output_stats(cpi, cpi->output_pkt_list, &cpi->twopass.total_stats);
 }
 static void zz_motion_search( VP8_COMP *cpi, MACROBLOCK * x,
                               YV12_BUFFER_CONFIG * raw_buffer,
                               int * raw_motion_err,
                               YV12_BUFFER_CONFIG * recon_buffer,
                               int * best_motion_err, int recon_yoffset)
 {
     MACROBLOCKD * const xd = & x->e_mbd;
     BLOCK *b = &x->block[0];
     BLOCKD *d = &x->e_mbd.block[0];
     unsigned char *src_ptr = (*(b->base_src) + b->src);
     int src_stride = b->src_stride;
     unsigned char *raw_ptr;
     int raw_stride = raw_buffer->y_stride;
     unsigned char *ref_ptr;
     int ref_stride = x->e_mbd.pre.y_stride;
     /* Set up pointers for this macro block raw buffer */
     raw_ptr = (unsigned char *)(raw_buffer->y_buffer + recon_yoffset
                                 + d->offset);
     vp8_mse16x16 ( src_ptr, src_stride, raw_ptr, raw_stride,
                    (unsigned int *)(raw_motion_err));
     /* Set up pointers for this macro block recon buffer */
     xd->pre.y_buffer = recon_buffer->y_buffer + recon_yoffset;
     ref_ptr = (unsigned char *)(xd->pre.y_buffer + d->offset );
     vp8_mse16x16 ( src_ptr, src_stride, ref_ptr, ref_stride,
                    (unsigned int *)(best_motion_err));
 }
 static void first_pass_motion_search(VP8_COMP *cpi, MACROBLOCK *x,
                                      int_mv *ref_mv, MV *best_mv,
                                      YV12_BUFFER_CONFIG *recon_buffer,
                                      int *best_motion_err, int recon_yoffset )
 {
     MACROBLOCKD *const xd = & x->e_mbd;
     BLOCK *b = &x->block[0];
     BLOCKD *d = &x->e_mbd.block[0];
     int num00;
     int_mv tmp_mv;
     int_mv ref_mv_full;
     int tmp_err;
     int step_param = 3; /* Dont search over full range for first pass */
     int further_steps = (MAX_MVSEARCH_STEPS - 1) - step_param;
     int n;
     vp8_variance_fn_ptr_t v_fn_ptr = cpi->fn_ptr[BLOCK_16X16];
     int new_mv_mode_penalty = 256;
     /* override the default variance function to use MSE */
     v_fn_ptr.vf    = vp8_mse16x16;
     /* Set up pointers for this macro block recon buffer */
     xd->pre.y_buffer = recon_buffer->y_buffer + recon_yoffset;
     /* Initial step/diamond search centred on best mv */
     tmp_mv.as_int = 0;
     ref_mv_full.as_mv.col = ref_mv->as_mv.col>>3;
     ref_mv_full.as_mv.row = ref_mv->as_mv.row>>3;
     tmp_err = cpi->diamond_search_sad(x, b, d, &ref_mv_full, &tmp_mv, step_param,
                                       x->sadperbit16, &num00, &v_fn_ptr,
                                       x->mvcost, ref_mv);
     if ( tmp_err < INT_MAX-new_mv_mode_penalty )
         tmp_err += new_mv_mode_penalty;
     if (tmp_err < *best_motion_err)
     {
         *best_motion_err = tmp_err;
         best_mv->row = tmp_mv.as_mv.row;
         best_mv->col = tmp_mv.as_mv.col;
     }
     /* Further step/diamond searches as necessary */
     n = num00;
     num00 = 0;
     while (n < further_steps)
     {
         n++;
         if (num00)
             num00--;
         else
         {
             tmp_err = cpi->diamond_search_sad(x, b, d, &ref_mv_full, &tmp_mv,
                                               step_param + n, x->sadperbit16,
                                               &num00, &v_fn_ptr, x->mvcost,
                                               ref_mv);
             if ( tmp_err < INT_MAX-new_mv_mode_penalty )
                 tmp_err += new_mv_mode_penalty;
             if (tmp_err < *best_motion_err)
             {
                 *best_motion_err = tmp_err;
                 best_mv->row = tmp_mv.as_mv.row;
                 best_mv->col = tmp_mv.as_mv.col;
             }
         }
     }
 }
 void vp8_first_pass(VP8_COMP *cpi)
 {
     int mb_row, mb_col;
     MACROBLOCK *const x = & cpi->mb;
     VP8_COMMON *const cm = & cpi->common;
     MACROBLOCKD *const xd = & x->e_mbd;
     int recon_yoffset, recon_uvoffset;
     YV12_BUFFER_CONFIG *lst_yv12 = &cm->yv12_fb[cm->lst_fb_idx];
     YV12_BUFFER_CONFIG *new_yv12 = &cm->yv12_fb[cm->new_fb_idx];
     YV12_BUFFER_CONFIG *gld_yv12 = &cm->yv12_fb[cm->gld_fb_idx];
     int recon_y_stride = lst_yv12->y_stride;
     int recon_uv_stride = lst_yv12->uv_stride;
     int64_t intra_error = 0;
     int64_t coded_error = 0;
     int sum_mvr = 0, sum_mvc = 0;
     int sum_mvr_abs = 0, sum_mvc_abs = 0;
     int sum_mvrs = 0, sum_mvcs = 0;
     int mvcount = 0;
     int intercount = 0;
     int second_ref_count = 0;
     int intrapenalty = 256;
     int neutral_count = 0;
     int new_mv_count = 0;
     int sum_in_vectors = 0;
     uint32_t lastmv_as_int = 0;
     int_mv zero_ref_mv;
     zero_ref_mv.as_int = 0;
     vp8_clear_system_state();
     x->src = * cpi->Source;
     xd->pre = *lst_yv12;
     xd->dst = *new_yv12;
     x->partition_info = x->pi;
     xd->mode_info_context = cm->mi;
     if(!cm->use_bilinear_mc_filter)
     {
          xd->subpixel_predict        = vp8_sixtap_predict4x4;
          xd->subpixel_predict8x4     = vp8_sixtap_predict8x4;
          xd->subpixel_predict8x8     = vp8_sixtap_predict8x8;
          xd->subpixel_predict16x16   = vp8_sixtap_predict16x16;
      }
      else
      {
          xd->subpixel_predict        = vp8_bilinear_predict4x4;
          xd->subpixel_predict8x4     = vp8_bilinear_predict8x4;
          xd->subpixel_predict8x8     = vp8_bilinear_predict8x8;
          xd->subpixel_predict16x16   = vp8_bilinear_predict16x16;
      }
     vp8_build_block_offsets(x);
     /* set up frame new frame for intra coded blocks */
     vp8_setup_intra_recon(new_yv12);
     vp8cx_frame_init_quantizer(cpi);
     /* Initialise the MV cost table to the defaults */
     {
         int flag[2] = {1, 1};
         vp8_initialize_rd_consts(cpi, x, vp8_dc_quant(cm->base_qindex, cm->y1dc_delta_q));
         vpx_memcpy(cm->fc.mvc, vp8_default_mv_context, sizeof(vp8_default_mv_context));
         vp8_build_component_cost_table(cpi->mb.mvcost, (const MV_CONTEXT *) cm->fc.mvc, flag);
     }
     /* for each macroblock row in image */
     for (mb_row = 0; mb_row < cm->mb_rows; mb_row++)
     {
         int_mv best_ref_mv;
         best_ref_mv.as_int = 0;
         /* reset above block coeffs */
         xd->up_available = (mb_row != 0);
         recon_yoffset = (mb_row * recon_y_stride * 16);
         recon_uvoffset = (mb_row * recon_uv_stride * 8);
         /* Set up limit values for motion vectors to prevent them extending
          * outside the UMV borders
          */
         x->mv_row_min = -((mb_row * 16) + (VP8BORDERINPIXELS - 16));
         x->mv_row_max = ((cm->mb_rows - 1 - mb_row) * 16) + (VP8BORDERINPIXELS - 16);
         /* for each macroblock col in image */
         for (mb_col = 0; mb_col < cm->mb_cols; mb_col++)
         {
             int this_error;
             int gf_motion_error = INT_MAX;
             int use_dc_pred = (mb_col || mb_row) && (!mb_col || !mb_row);
             xd->dst.y_buffer = new_yv12->y_buffer + recon_yoffset;
             xd->dst.u_buffer = new_yv12->u_buffer + recon_uvoffset;
             xd->dst.v_buffer = new_yv12->v_buffer + recon_uvoffset;
             xd->left_available = (mb_col != 0);
             /* Copy current mb to a buffer */
             vp8_copy_mem16x16(x->src.y_buffer, x->src.y_stride, x->thismb, 16);
             /* do intra 16x16 prediction */
             this_error = vp8_encode_intra(cpi, x, use_dc_pred);
             /* "intrapenalty" below deals with situations where the intra
              * and inter error scores are very low (eg a plain black frame)
              * We do not have special cases in first pass for 0,0 and
              * nearest etc so all inter modes carry an overhead cost
              * estimate fot the mv. When the error score is very low this
              * causes us to pick all or lots of INTRA modes and throw lots
              * of key frames. This penalty adds a cost matching that of a
              * 0,0 mv to the intra case.
              */
             this_error += intrapenalty;
             /* Cumulative intra error total */
             intra_error += (int64_t)this_error;
             /* Set up limit values for motion vectors to prevent them
              * extending outside the UMV borders
              */
             x->mv_col_min = -((mb_col * 16) + (VP8BORDERINPIXELS - 16));
             x->mv_col_max = ((cm->mb_cols - 1 - mb_col) * 16) + (VP8BORDERINPIXELS - 16);
             /* Other than for the first frame do a motion search */
             if (cm->current_video_frame > 0)
             {
                 BLOCKD *d = &x->e_mbd.block[0];
                 MV tmp_mv = {0, 0};
                 int tmp_err;
                 int motion_error = INT_MAX;
                 int raw_motion_error = INT_MAX;
                 /* Simple 0,0 motion with no mv overhead */
                 zz_motion_search( cpi, x, cpi->last_frame_unscaled_source,
                                   &raw_motion_error, lst_yv12, &motion_error,
                                   recon_yoffset );
                 d->bmi.mv.as_mv.row = 0;
                 d->bmi.mv.as_mv.col = 0;
                 if (raw_motion_error < cpi->oxcf.encode_breakout)
                     goto skip_motion_search;
                 /* Test last reference frame using the previous best mv as the
                  * starting point (best reference) for the search
                  */
                 first_pass_motion_search(cpi, x, &best_ref_mv,
                                         &d->bmi.mv.as_mv, lst_yv12,
                                         &motion_error, recon_yoffset);
                 /* If the current best reference mv is not centred on 0,0
                  * then do a 0,0 based search as well
                  */
                 if (best_ref_mv.as_int)
                 {
                    tmp_err = INT_MAX;
                    first_pass_motion_search(cpi, x, &zero_ref_mv, &tmp_mv,
                                      lst_yv12, &tmp_err, recon_yoffset);
                    if ( tmp_err < motion_error )
                    {
                         motion_error = tmp_err;
                         d->bmi.mv.as_mv.row = tmp_mv.row;
                         d->bmi.mv.as_mv.col = tmp_mv.col;
                    }
                 }
                 /* Experimental search in a second reference frame ((0,0)
                  * based only)
                  */
                 if (cm->current_video_frame > 1)
                 {
                     first_pass_motion_search(cpi, x, &zero_ref_mv, &tmp_mv, gld_yv12, &gf_motion_error, recon_yoffset);
                     if ((gf_motion_error < motion_error) && (gf_motion_error < this_error))
                     {
                         second_ref_count++;
                     }
                     /* Reset to last frame as reference buffer */
                     xd->pre.y_buffer = lst_yv12->y_buffer + recon_yoffset;
                     xd->pre.u_buffer = lst_yv12->u_buffer + recon_uvoffset;
                     xd->pre.v_buffer = lst_yv12->v_buffer + recon_uvoffset;
                 }
 skip_motion_search:
                 /* Intra assumed best */
                 best_ref_mv.as_int = 0;
                 if (motion_error <= this_error)
                 {
                     /* Keep a count of cases where the inter and intra were
                      * very close and very low. This helps with scene cut
                      * detection for example in cropped clips with black bars
                      * at the sides or top and bottom.
                      */
                     if( (((this_error-intrapenalty) * 9) <=
                          (motion_error*10)) &&
                         (this_error < (2*intrapenalty)) )
                     {
                         neutral_count++;
                     }
                     d->bmi.mv.as_mv.row *= 8;
                     d->bmi.mv.as_mv.col *= 8;
                     this_error = motion_error;
                     vp8_set_mbmode_and_mvs(x, NEWMV, &d->bmi.mv);
                     vp8_encode_inter16x16y(x);
                     sum_mvr += d->bmi.mv.as_mv.row;
                     sum_mvr_abs += abs(d->bmi.mv.as_mv.row);
                     sum_mvc += d->bmi.mv.as_mv.col;
                     sum_mvc_abs += abs(d->bmi.mv.as_mv.col);
                     sum_mvrs += d->bmi.mv.as_mv.row * d->bmi.mv.as_mv.row;
                     sum_mvcs += d->bmi.mv.as_mv.col * d->bmi.mv.as_mv.col;
                     intercount++;
                     best_ref_mv.as_int = d->bmi.mv.as_int;
                     /* Was the vector non-zero */
                     if (d->bmi.mv.as_int)
                     {
                         mvcount++;
                         /* Was it different from the last non zero vector */
                         if ( d->bmi.mv.as_int != lastmv_as_int )
                             new_mv_count++;
                         lastmv_as_int = d->bmi.mv.as_int;
                         /* Does the Row vector point inwards or outwards */
                         if (mb_row < cm->mb_rows / 2)
                         {
                             if (d->bmi.mv.as_mv.row > 0)
                                 sum_in_vectors--;
                             else if (d->bmi.mv.as_mv.row < 0)
                                 sum_in_vectors++;
                         }
                         else if (mb_row > cm->mb_rows / 2)
                         {
                             if (d->bmi.mv.as_mv.row > 0)
                                 sum_in_vectors++;
                             else if (d->bmi.mv.as_mv.row < 0)
                                 sum_in_vectors--;
                         }
                         /* Does the Row vector point inwards or outwards */
                         if (mb_col < cm->mb_cols / 2)
                         {
                             if (d->bmi.mv.as_mv.col > 0)
                                 sum_in_vectors--;
                             else if (d->bmi.mv.as_mv.col < 0)
                                 sum_in_vectors++;
                         }
                         else if (mb_col > cm->mb_cols / 2)
                         {
                             if (d->bmi.mv.as_mv.col > 0)
                                 sum_in_vectors++;
                             else if (d->bmi.mv.as_mv.col < 0)
                                 sum_in_vectors--;
                         }
                     }
                 }
             }
             coded_error += (int64_t)this_error;
             /* adjust to the next column of macroblocks */
             x->src.y_buffer += 16;
             x->src.u_buffer += 8;
             x->src.v_buffer += 8;
             recon_yoffset += 16;
             recon_uvoffset += 8;
         }
         /* adjust to the next row of mbs */
         x->src.y_buffer += 16 * x->src.y_stride - 16 * cm->mb_cols;
         x->src.u_buffer += 8 * x->src.uv_stride - 8 * cm->mb_cols;
         x->src.v_buffer += 8 * x->src.uv_stride - 8 * cm->mb_cols;
         /* extend the recon for intra prediction */
         vp8_extend_mb_row(new_yv12, xd->dst.y_buffer + 16, xd->dst.u_buffer + 8, xd->dst.v_buffer + 8);
         vp8_clear_system_state();
     }
     vp8_clear_system_state();
     {
         double weight = 0.0;
         FIRSTPASS_STATS fps;
         fps.frame      = cm->current_video_frame ;
         fps.intra_error = (double)(intra_error >> 8);
         fps.coded_error = (double)(coded_error >> 8);
         weight = simple_weight(cpi->Source);
         if (weight < 0.1)
             weight = 0.1;
         fps.ssim_weighted_pred_err = fps.coded_error * weight;
         fps.pcnt_inter  = 0.0;
         fps.pcnt_motion = 0.0;
         fps.MVr        = 0.0;
         fps.mvr_abs     = 0.0;
         fps.MVc        = 0.0;
         fps.mvc_abs     = 0.0;
         fps.MVrv       = 0.0;
         fps.MVcv       = 0.0;
         fps.mv_in_out_count  = 0.0;
         fps.new_mv_count = 0.0;
         fps.count      = 1.0;
         fps.pcnt_inter   = 1.0 * (double)intercount / cm->MBs;
         fps.pcnt_second_ref = 1.0 * (double)second_ref_count / cm->MBs;
         fps.pcnt_neutral = 1.0 * (double)neutral_count / cm->MBs;
         if (mvcount > 0)
         {
             fps.MVr = (double)sum_mvr / (double)mvcount;
             fps.mvr_abs = (double)sum_mvr_abs / (double)mvcount;
             fps.MVc = (double)sum_mvc / (double)mvcount;
             fps.mvc_abs = (double)sum_mvc_abs / (double)mvcount;
             fps.MVrv = ((double)sum_mvrs - (fps.MVr * fps.MVr / (double)mvcount)) / (double)mvcount;
             fps.MVcv = ((double)sum_mvcs - (fps.MVc * fps.MVc / (double)mvcount)) / (double)mvcount;
             fps.mv_in_out_count = (double)sum_in_vectors / (double)(mvcount * 2);
             fps.new_mv_count = new_mv_count;
             fps.pcnt_motion = 1.0 * (double)mvcount / cpi->common.MBs;
         }
         /* TODO:  handle the case when duration is set to 0, or something less
          * than the full time between subsequent cpi->source_time_stamps
          */
         fps.duration = (double)(cpi->source->ts_end
                        - cpi->source->ts_start);
         /* don't want to do output stats with a stack variable! */
         memcpy(&cpi->twopass.this_frame_stats,
                &fps,
                sizeof(FIRSTPASS_STATS));
         output_stats(cpi, cpi->output_pkt_list, &cpi->twopass.this_frame_stats);
         accumulate_stats(&cpi->twopass.total_stats, &fps);
     }
     /* Copy the previous Last Frame into the GF buffer if specific
      * conditions for doing so are met
      */
     if ((cm->current_video_frame > 0) &&
         (cpi->twopass.this_frame_stats.pcnt_inter > 0.20) &&
         ((cpi->twopass.this_frame_stats.intra_error /
           DOUBLE_DIVIDE_CHECK(cpi->twopass.this_frame_stats.coded_error)) >
 .0))
     {
         vp8_yv12_copy_frame(lst_yv12, gld_yv12);
     }
     /* swap frame pointers so last frame refers to the frame we just
      * compressed
      */
     vp8_swap_yv12_buffer(lst_yv12, new_yv12);
     vp8_yv12_extend_frame_borders(lst_yv12);
     /* Special case for the first frame. Copy into the GF buffer as a
      * second reference.
      */
     if (cm->current_video_frame == 0)
     {
         vp8_yv12_copy_frame(lst_yv12, gld_yv12);
     }
     /* use this to see what the first pass reconstruction looks like */
     if (0)
     {
         char filename[512];
         FILE *recon_file;
         sprintf(filename, "enc%04d.yuv", (int) cm->current_video_frame);
         if (cm->current_video_frame == 0)
             recon_file = fopen(filename, "wb");
         else
             recon_file = fopen(filename, "ab");
         (void) fwrite(lst_yv12->buffer_alloc, lst_yv12->frame_size, 1,
                       recon_file);
         fclose(recon_file);
     }
     cm->current_video_frame++;
 }
 extern const int vp8_bits_per_mb[2][QINDEX_RANGE];
 /* Estimate a cost per mb attributable to overheads such as the coding of
  * modes and motion vectors.
  * Currently simplistic in its assumptions for testing.
  */
 static double bitcost( double prob )
 {
   if (prob > 0.000122)
     return -log(prob) / log(2.0);
   else
     return 13.0;
 }
 static int64_t estimate_modemvcost(VP8_COMP *cpi,
                                      FIRSTPASS_STATS * fpstats)
 {
     int mv_cost;
     int64_t mode_cost;
     double av_pct_inter = fpstats->pcnt_inter / fpstats->count;
     double av_pct_motion = fpstats->pcnt_motion / fpstats->count;
     double av_intra = (1.0 - av_pct_inter);
     double zz_cost;
     double motion_cost;
     double intra_cost;
     zz_cost = bitcost(av_pct_inter - av_pct_motion);
     motion_cost = bitcost(av_pct_motion);
     intra_cost = bitcost(av_intra);
     /* Estimate of extra bits per mv overhead for mbs
      * << 9 is the normalization to the (bits * 512) used in vp8_bits_per_mb
      */
     mv_cost = ((int)(fpstats->new_mv_count / fpstats->count) * 8) << 9;
     /* Crude estimate of overhead cost from modes
      * << 9 is the normalization to (bits * 512) used in vp8_bits_per_mb
      */
     mode_cost =((((av_pct_inter - av_pct_motion) * zz_cost) +
                 (av_pct_motion * motion_cost) +
                 (av_intra * intra_cost)) * cpi->common.MBs) * 512;
     return mv_cost + mode_cost;
 }
 static double calc_correction_factor( double err_per_mb,
                                       double err_devisor,
                                       double pt_low,
                                       double pt_high,
                                       int Q )
 {
     double power_term;
     double error_term = err_per_mb / err_devisor;
     double correction_factor;
     /* Adjustment based on Q to power term. */
     power_term = pt_low + (Q * 0.01);
     power_term = (power_term > pt_high) ? pt_high : power_term;
     /* Adjustments to error term */
     /* TBD */
     /* Calculate correction factor */
     correction_factor = pow(error_term, power_term);
     /* Clip range */
     correction_factor =
         (correction_factor < 0.05)
             ? 0.05 : (correction_factor > 5.0) ? 5.0 : correction_factor;
     return correction_factor;
 }
 static int estimate_max_q(VP8_COMP *cpi,
                           FIRSTPASS_STATS * fpstats,
                           int section_target_bandwitdh,
                           int overhead_bits )
 {
     int Q;
     int num_mbs = cpi->common.MBs;
     int target_norm_bits_per_mb;
     double section_err = (fpstats->coded_error / fpstats->count);
     double err_per_mb = section_err / num_mbs;
     double err_correction_factor;
     double speed_correction = 1.0;
     int overhead_bits_per_mb;
     if (section_target_bandwitdh <= 0)
         return cpi->twopass.maxq_max_limit;       /* Highest value allowed */
     target_norm_bits_per_mb =
         (section_target_bandwitdh < (1 << 20))
             ? (512 * section_target_bandwitdh) / num_mbs
             : 512 * (section_target_bandwitdh / num_mbs);
     /* Calculate a corrective factor based on a rolling ratio of bits spent
      * vs target bits
      */
     if ((cpi->rolling_target_bits > 0) &&
         (cpi->active_worst_quality < cpi->worst_quality))
     {
         double rolling_ratio;
         rolling_ratio = (double)cpi->rolling_actual_bits /
                         (double)cpi->rolling_target_bits;
         if (rolling_ratio < 0.95)
             cpi->twopass.est_max_qcorrection_factor -= 0.005;
         else if (rolling_ratio > 1.05)
             cpi->twopass.est_max_qcorrection_factor += 0.005;
         cpi->twopass.est_max_qcorrection_factor =
             (cpi->twopass.est_max_qcorrection_factor < 0.1)
                 ? 0.1
                 : (cpi->twopass.est_max_qcorrection_factor > 10.0)
                     ? 10.0 : cpi->twopass.est_max_qcorrection_factor;
     }
     /* Corrections for higher compression speed settings
      * (reduced compression expected)
      */
     if ((cpi->compressor_speed == 3) || (cpi->compressor_speed == 1))
     {
         if (cpi->oxcf.cpu_used <= 5)
             speed_correction = 1.04 + (cpi->oxcf.cpu_used * 0.04);
         else
             speed_correction = 1.25;
     }
     /* Estimate of overhead bits per mb */
     /* Correction to overhead bits for min allowed Q. */
     overhead_bits_per_mb = overhead_bits / num_mbs;
     overhead_bits_per_mb = (int)(overhead_bits_per_mb *
                             pow( 0.98, (double)cpi->twopass.maxq_min_limit ));
     /* Try and pick a max Q that will be high enough to encode the
      * content at the given rate.
      */
     for (Q = cpi->twopass.maxq_min_limit; Q < cpi->twopass.maxq_max_limit; Q++)
     {
         int bits_per_mb_at_this_q;
         /* Error per MB based correction factor */
         err_correction_factor =
             calc_correction_factor(err_per_mb, 150.0, 0.40, 0.90, Q);
         bits_per_mb_at_this_q =
             vp8_bits_per_mb[INTER_FRAME][Q] + overhead_bits_per_mb;
         bits_per_mb_at_this_q = (int)(.5 + err_correction_factor
             * speed_correction * cpi->twopass.est_max_qcorrection_factor
             * cpi->twopass.section_max_qfactor
             * (double)bits_per_mb_at_this_q);
         /* Mode and motion overhead */
         /* As Q rises in real encode loop rd code will force overhead down
          * We make a crude adjustment for this here as *.98 per Q step.
          */
         overhead_bits_per_mb = (int)((double)overhead_bits_per_mb * 0.98);
         if (bits_per_mb_at_this_q <= target_norm_bits_per_mb)
             break;
     }
     /* Restriction on active max q for constrained quality mode. */
     if ( (cpi->oxcf.end_usage == USAGE_CONSTRAINED_QUALITY) &&
          (Q < cpi->cq_target_quality) )
     {
         Q = cpi->cq_target_quality;
     }
     /* Adjust maxq_min_limit and maxq_max_limit limits based on
      * average q observed in clip for non kf/gf.arf frames
      * Give average a chance to settle though.
      */
     if ( (cpi->ni_frames >
                   ((int)cpi->twopass.total_stats.count >> 8)) &&
          (cpi->ni_frames > 150) )
     {
         cpi->twopass.maxq_max_limit = ((cpi->ni_av_qi + 32) < cpi->worst_quality)
                                   ? (cpi->ni_av_qi + 32) : cpi->worst_quality;
         cpi->twopass.maxq_min_limit = ((cpi->ni_av_qi - 32) > cpi->best_quality)
                                   ? (cpi->ni_av_qi - 32) : cpi->best_quality;
     }
     return Q;
 }
 /* For cq mode estimate a cq level that matches the observed
  * complexity and data rate.
  */
 static int estimate_cq( VP8_COMP *cpi,
                         FIRSTPASS_STATS * fpstats,
                         int section_target_bandwitdh,
                         int overhead_bits )
 {
     int Q;
     int num_mbs = cpi->common.MBs;
     int target_norm_bits_per_mb;
     double section_err = (fpstats->coded_error / fpstats->count);
     double err_per_mb = section_err / num_mbs;
     double err_correction_factor;
     double speed_correction = 1.0;
     double clip_iiratio;
     double clip_iifactor;
     int overhead_bits_per_mb;
     if (0)
     {
         FILE *f = fopen("epmp.stt", "a");
         fprintf(f, "%10.2f\n", err_per_mb );
         fclose(f);
     }
     target_norm_bits_per_mb = (section_target_bandwitdh < (1 << 20))
                               ? (512 * section_target_bandwitdh) / num_mbs
                               : 512 * (section_target_bandwitdh / num_mbs);
     /* Estimate of overhead bits per mb */
     overhead_bits_per_mb = overhead_bits / num_mbs;
     /* Corrections for higher compression speed settings
      * (reduced compression expected)
      */
     if ((cpi->compressor_speed == 3) || (cpi->compressor_speed == 1))
     {
         if (cpi->oxcf.cpu_used <= 5)
             speed_correction = 1.04 + (cpi->oxcf.cpu_used * 0.04);
         else
             speed_correction = 1.25;
     }
     /* II ratio correction factor for clip as a whole */
     clip_iiratio = cpi->twopass.total_stats.intra_error /
                    DOUBLE_DIVIDE_CHECK(cpi->twopass.total_stats.coded_error);
     clip_iifactor = 1.0 - ((clip_iiratio - 10.0) * 0.025);
     if (clip_iifactor < 0.80)
         clip_iifactor = 0.80;
     /* Try and pick a Q that can encode the content at the given rate. */
     for (Q = 0; Q < MAXQ; Q++)
     {
         int bits_per_mb_at_this_q;
         /* Error per MB based correction factor */
         err_correction_factor =
             calc_correction_factor(err_per_mb, 100.0, 0.40, 0.90, Q);
         bits_per_mb_at_this_q =
             vp8_bits_per_mb[INTER_FRAME][Q] + overhead_bits_per_mb;
         bits_per_mb_at_this_q =
             (int)( .5 + err_correction_factor *
                         speed_correction *
                         clip_iifactor *
                         (double)bits_per_mb_at_this_q);
         /* Mode and motion overhead */
         /* As Q rises in real encode loop rd code will force overhead down
          * We make a crude adjustment for this here as *.98 per Q step.
          */
         overhead_bits_per_mb = (int)((double)overhead_bits_per_mb * 0.98);
         if (bits_per_mb_at_this_q <= target_norm_bits_per_mb)
             break;
     }
     /* Clip value to range "best allowed to (worst allowed - 1)" */
     Q = cq_level[Q];
     if ( Q >= cpi->worst_quality )
         Q = cpi->worst_quality - 1;
     if ( Q < cpi->best_quality )
         Q = cpi->best_quality;
     return Q;
 }
 static int estimate_q(VP8_COMP *cpi, double section_err, int section_target_bandwitdh)
 {
     int Q;
     int num_mbs = cpi->common.MBs;
     int target_norm_bits_per_mb;
     double err_per_mb = section_err / num_mbs;
     double err_correction_factor;
     double speed_correction = 1.0;
     target_norm_bits_per_mb = (section_target_bandwitdh < (1 << 20)) ? (512 * section_target_bandwitdh) / num_mbs : 512 * (section_target_bandwitdh / num_mbs);
     /* Corrections for higher compression speed settings
      * (reduced compression expected)
      */
     if ((cpi->compressor_speed == 3) || (cpi->compressor_speed == 1))
     {
         if (cpi->oxcf.cpu_used <= 5)
             speed_correction = 1.04 + (cpi->oxcf.cpu_used * 0.04);
         else
             speed_correction = 1.25;
     }
     /* Try and pick a Q that can encode the content at the given rate. */
     for (Q = 0; Q < MAXQ; Q++)
     {
         int bits_per_mb_at_this_q;
         /* Error per MB based correction factor */
         err_correction_factor =
             calc_correction_factor(err_per_mb, 150.0, 0.40, 0.90, Q);
         bits_per_mb_at_this_q =
             (int)( .5 + ( err_correction_factor *
                           speed_correction *
                           cpi->twopass.est_max_qcorrection_factor *
                           (double)vp8_bits_per_mb[INTER_FRAME][Q] / 1.0 ) );
         if (bits_per_mb_at_this_q <= target_norm_bits_per_mb)
             break;
     }
     return Q;
 }
 /* Estimate a worst case Q for a KF group */
 static int estimate_kf_group_q(VP8_COMP *cpi, double section_err, int section_target_bandwitdh, double group_iiratio)
 {
     int Q;
     int num_mbs = cpi->common.MBs;
     int target_norm_bits_per_mb = (512 * section_target_bandwitdh) / num_mbs;
     int bits_per_mb_at_this_q;
     double err_per_mb = section_err / num_mbs;
     double err_correction_factor;
     double speed_correction = 1.0;
     double current_spend_ratio = 1.0;
     double pow_highq = (POW1 < 0.6) ? POW1 + 0.3 : 0.90;
     double pow_lowq = (POW1 < 0.7) ? POW1 + 0.1 : 0.80;
     double iiratio_correction_factor = 1.0;
     double combined_correction_factor;
     /* Trap special case where the target is <= 0 */
     if (target_norm_bits_per_mb <= 0)
         return MAXQ * 2;
     /* Calculate a corrective factor based on a rolling ratio of bits spent
      *  vs target bits
      * This is clamped to the range 0.1 to 10.0
      */
     if (cpi->long_rolling_target_bits <= 0)
         current_spend_ratio = 10.0;
     else
     {
         current_spend_ratio = (double)cpi->long_rolling_actual_bits / (double)cpi->long_rolling_target_bits;
         current_spend_ratio = (current_spend_ratio > 10.0) ? 10.0 : (current_spend_ratio < 0.1) ? 0.1 : current_spend_ratio;
     }
     /* Calculate a correction factor based on the quality of prediction in
      * the sequence as indicated by intra_inter error score ratio (IIRatio)
      * The idea here is to favour subsampling in the hardest sections vs
      * the easyest.
      */
     iiratio_correction_factor = 1.0 - ((group_iiratio - 6.0) * 0.1);
     if (iiratio_correction_factor < 0.5)
         iiratio_correction_factor = 0.5;
     /* Corrections for higher compression speed settings
      * (reduced compression expected)
      */
     if ((cpi->compressor_speed == 3) || (cpi->compressor_speed == 1))
     {
         if (cpi->oxcf.cpu_used <= 5)
             speed_correction = 1.04 + (cpi->oxcf.cpu_used * 0.04);
         else
             speed_correction = 1.25;
     }
     /* Combine the various factors calculated above */
     combined_correction_factor = speed_correction * iiratio_correction_factor * current_spend_ratio;
     /* Try and pick a Q that should be high enough to encode the content at
      * the given rate.
      */
     for (Q = 0; Q < MAXQ; Q++)
     {
         /* Error per MB based correction factor */
         err_correction_factor =
             calc_correction_factor(err_per_mb, 150.0, pow_lowq, pow_highq, Q);
         bits_per_mb_at_this_q =
             (int)(.5 + ( err_correction_factor *
                          combined_correction_factor *
                          (double)vp8_bits_per_mb[INTER_FRAME][Q]) );
         if (bits_per_mb_at_this_q <= target_norm_bits_per_mb)
             break;
     }
     /* If we could not hit the target even at Max Q then estimate what Q
      * would have been required
      */
     while ((bits_per_mb_at_this_q > target_norm_bits_per_mb)  && (Q < (MAXQ * 2)))
     {
         bits_per_mb_at_this_q = (int)(0.96 * bits_per_mb_at_this_q);
         Q++;
     }
     if (0)
     {
         FILE *f = fopen("estkf_q.stt", "a");
         fprintf(f, "%8d %8d %8d %8.2f %8.3f %8.2f %8.3f %8.3f %8.3f %8d\n", cpi->common.current_video_frame, bits_per_mb_at_this_q,
                 target_norm_bits_per_mb, err_per_mb, err_correction_factor,
                 current_spend_ratio, group_iiratio, iiratio_correction_factor,
                 (double)cpi->buffer_level / (double)cpi->oxcf.optimal_buffer_level, Q);
         fclose(f);
     }
     return Q;
 }
 extern void vp8_new_framerate(VP8_COMP *cpi, double framerate);
 void vp8_init_second_pass(VP8_COMP *cpi)
 {
     FIRSTPASS_STATS this_frame;
     FIRSTPASS_STATS *start_pos;
     double two_pass_min_rate = (double)(cpi->oxcf.target_bandwidth * cpi->oxcf.two_pass_vbrmin_section / 100);
     zero_stats(&cpi->twopass.total_stats);
     zero_stats(&cpi->twopass.total_left_stats);
     if (!cpi->twopass.stats_in_end)
         return;
     cpi->twopass.total_stats = *cpi->twopass.stats_in_end;
     cpi->twopass.total_left_stats = cpi->twopass.total_stats;
     /* each frame can have a different duration, as the frame rate in the
      * source isn't guaranteed to be constant.   The frame rate prior to
      * the first frame encoded in the second pass is a guess.  However the
      * sum duration is not. Its calculated based on the actual durations of
      * all frames from the first pass.
      */
     vp8_new_framerate(cpi, 10000000.0 * cpi->twopass.total_stats.count / cpi->twopass.total_stats.duration);
     cpi->output_framerate = cpi->framerate;
     cpi->twopass.bits_left = (int64_t)(cpi->twopass.total_stats.duration * cpi->oxcf.target_bandwidth / 10000000.0) ;
     cpi->twopass.bits_left -= (int64_t)(cpi->twopass.total_stats.duration * two_pass_min_rate / 10000000.0);
     /* Calculate a minimum intra value to be used in determining the IIratio
      * scores used in the second pass. We have this minimum to make sure
      * that clips that are static but "low complexity" in the intra domain
      * are still boosted appropriately for KF/GF/ARF
      */
     cpi->twopass.kf_intra_err_min = KF_MB_INTRA_MIN * cpi->common.MBs;
     cpi->twopass.gf_intra_err_min = GF_MB_INTRA_MIN * cpi->common.MBs;
     /* Scan the first pass file and calculate an average Intra / Inter error
      * score ratio for the sequence
      */
     {
         double sum_iiratio = 0.0;
         double IIRatio;
         start_pos = cpi->twopass.stats_in; /* Note starting "file" position */
         while (input_stats(cpi, &this_frame) != EOF)
         {
             IIRatio = this_frame.intra_error / DOUBLE_DIVIDE_CHECK(this_frame.coded_error);
             IIRatio = (IIRatio < 1.0) ? 1.0 : (IIRatio > 20.0) ? 20.0 : IIRatio;
             sum_iiratio += IIRatio;
         }
         cpi->twopass.avg_iiratio = sum_iiratio / DOUBLE_DIVIDE_CHECK((double)cpi->twopass.total_stats.count);
         /* Reset file position */
         reset_fpf_position(cpi, start_pos);
     }
     /* Scan the first pass file and calculate a modified total error based
      * upon the bias/power function used to allocate bits
      */
     {
         start_pos = cpi->twopass.stats_in;  /* Note starting "file" position */
         cpi->twopass.modified_error_total = 0.0;
         cpi->twopass.modified_error_used = 0.0;
         while (input_stats(cpi, &this_frame) != EOF)
         {
             cpi->twopass.modified_error_total += calculate_modified_err(cpi, &this_frame);
         }
         cpi->twopass.modified_error_left = cpi->twopass.modified_error_total;
         reset_fpf_position(cpi, start_pos);  /* Reset file position */
     }
 }
 void vp8_end_second_pass(VP8_COMP *cpi)
 {
 }
 /* This function gives and estimate of how badly we believe the prediction
  * quality is decaying from frame to frame.
  */
 static double get_prediction_decay_rate(VP8_COMP *cpi, FIRSTPASS_STATS *next_frame)
 {
     double prediction_decay_rate;
     double motion_decay;
     double motion_pct = next_frame->pcnt_motion;
     /* Initial basis is the % mbs inter coded */
     prediction_decay_rate = next_frame->pcnt_inter;
     /* High % motion -> somewhat higher decay rate */
     motion_decay = (1.0 - (motion_pct / 20.0));
     if (motion_decay < prediction_decay_rate)
         prediction_decay_rate = motion_decay;
     /* Adjustment to decay rate based on speed of motion */
     {
         double this_mv_rabs;
         double this_mv_cabs;
         double distance_factor;
         this_mv_rabs = fabs(next_frame->mvr_abs * motion_pct);
         this_mv_cabs = fabs(next_frame->mvc_abs * motion_pct);
         distance_factor = sqrt((this_mv_rabs * this_mv_rabs) +
                                (this_mv_cabs * this_mv_cabs)) / 250.0;
         distance_factor = ((distance_factor > 1.0)
                                 ? 0.0 : (1.0 - distance_factor));
         if (distance_factor < prediction_decay_rate)
             prediction_decay_rate = distance_factor;
     }
     return prediction_decay_rate;
 }
 /* Function to test for a condition where a complex transition is followed
  * by a static section. For example in slide shows where there is a fade
  * between slides. This is to help with more optimal kf and gf positioning.
  */
 static int detect_transition_to_still(
     VP8_COMP *cpi,
     int frame_interval,
     int still_interval,
     double loop_decay_rate,
     double decay_accumulator )
 {
     int trans_to_still = 0;
     /* Break clause to detect very still sections after motion
      * For example a static image after a fade or other transition
      * instead of a clean scene cut.
      */
     if ( (frame_interval > MIN_GF_INTERVAL) &&
          (loop_decay_rate >= 0.999) &&
          (decay_accumulator < 0.9) )
     {
         int j;
         FIRSTPASS_STATS * position = cpi->twopass.stats_in;
         FIRSTPASS_STATS tmp_next_frame;
         double decay_rate;
         /* Look ahead a few frames to see if static condition persists... */
         for ( j = 0; j < still_interval; j++ )
         {
             if (EOF == input_stats(cpi, &tmp_next_frame))
                 break;
             decay_rate = get_prediction_decay_rate(cpi, &tmp_next_frame);
             if ( decay_rate < 0.999 )
                 break;
         }
         /* Reset file position */
         reset_fpf_position(cpi, position);
         /* Only if it does do we signal a transition to still */
         if ( j == still_interval )
             trans_to_still = 1;
     }
     return trans_to_still;
 }
 /* This function detects a flash through the high relative pcnt_second_ref
  * score in the frame following a flash frame. The offset passed in should
  * reflect this
  */
 static int detect_flash( VP8_COMP *cpi, int offset )
 {
     FIRSTPASS_STATS next_frame;
     int flash_detected = 0;
     /* Read the frame data. */
     /* The return is 0 (no flash detected) if not a valid frame */
     if ( read_frame_stats(cpi, &next_frame, offset) != EOF )
     {
         /* What we are looking for here is a situation where there is a
          * brief break in prediction (such as a flash) but subsequent frames
          * are reasonably well predicted by an earlier (pre flash) frame.
          * The recovery after a flash is indicated by a high pcnt_second_ref
          * comapred to pcnt_inter.
          */
         if ( (next_frame.pcnt_second_ref > next_frame.pcnt_inter) &&
              (next_frame.pcnt_second_ref >= 0.5 ) )
         {
             flash_detected = 1;
             /*if (1)
             {
                 FILE *f = fopen("flash.stt", "a");
                 fprintf(f, "%8.0f %6.2f %6.2f\n",
                     next_frame.frame,
                     next_frame.pcnt_inter,
                     next_frame.pcnt_second_ref);
                 fclose(f);
             }*/
         }
     }
     return flash_detected;
 }
 /* Update the motion related elements to the GF arf boost calculation */
 static void accumulate_frame_motion_stats(
     VP8_COMP *cpi,
     FIRSTPASS_STATS * this_frame,
     double * this_frame_mv_in_out,
     double * mv_in_out_accumulator,
     double * abs_mv_in_out_accumulator,
     double * mv_ratio_accumulator )
 {
     double this_frame_mvr_ratio;
     double this_frame_mvc_ratio;
     double motion_pct;
     /* Accumulate motion stats. */
     motion_pct = this_frame->pcnt_motion;
     /* Accumulate Motion In/Out of frame stats */
     *this_frame_mv_in_out = this_frame->mv_in_out_count * motion_pct;
     *mv_in_out_accumulator += this_frame->mv_in_out_count * motion_pct;
     *abs_mv_in_out_accumulator +=
         fabs(this_frame->mv_in_out_count * motion_pct);
     /* Accumulate a measure of how uniform (or conversely how random)
      * the motion field is. (A ratio of absmv / mv)
      */
     if (motion_pct > 0.05)
     {
         this_frame_mvr_ratio = fabs(this_frame->mvr_abs) /
                                DOUBLE_DIVIDE_CHECK(fabs(this_frame->MVr));
         this_frame_mvc_ratio = fabs(this_frame->mvc_abs) /
                                DOUBLE_DIVIDE_CHECK(fabs(this_frame->MVc));
          *mv_ratio_accumulator +=
             (this_frame_mvr_ratio < this_frame->mvr_abs)
                 ? (this_frame_mvr_ratio * motion_pct)
                 : this_frame->mvr_abs * motion_pct;
         *mv_ratio_accumulator +=
             (this_frame_mvc_ratio < this_frame->mvc_abs)
                 ? (this_frame_mvc_ratio * motion_pct)
                 : this_frame->mvc_abs * motion_pct;
     }
 }
 /* Calculate a baseline boost number for the current frame. */
 static double calc_frame_boost(
     VP8_COMP *cpi,
     FIRSTPASS_STATS * this_frame,
     double this_frame_mv_in_out )
 {
     double frame_boost;
     /* Underlying boost factor is based on inter intra error ratio */
     if (this_frame->intra_error > cpi->twopass.gf_intra_err_min)
         frame_boost = (IIFACTOR * this_frame->intra_error /
                       DOUBLE_DIVIDE_CHECK(this_frame->coded_error));
     else
         frame_boost = (IIFACTOR * cpi->twopass.gf_intra_err_min /
                       DOUBLE_DIVIDE_CHECK(this_frame->coded_error));
     /* Increase boost for frames where new data coming into frame
      * (eg zoom out). Slightly reduce boost if there is a net balance
      * of motion out of the frame (zoom in).
      * The range for this_frame_mv_in_out is -1.0 to +1.0
      */
     if (this_frame_mv_in_out > 0.0)
         frame_boost += frame_boost * (this_frame_mv_in_out * 2.0);
     /* In extreme case boost is halved */
     else
         frame_boost += frame_boost * (this_frame_mv_in_out / 2.0);
     /* Clip to maximum */
     if (frame_boost > GF_RMAX)
         frame_boost = GF_RMAX;
     return frame_boost;
 }
 #if NEW_BOOST
 static int calc_arf_boost(
     VP8_COMP *cpi,
     int offset,
     int f_frames,
     int b_frames,
     int *f_boost,
     int *b_boost )
 {
     FIRSTPASS_STATS this_frame;
     int i;
     double boost_score = 0.0;
     double mv_ratio_accumulator = 0.0;
     double decay_accumulator = 1.0;
     double this_frame_mv_in_out = 0.0;
     double mv_in_out_accumulator = 0.0;
     double abs_mv_in_out_accumulator = 0.0;
     double r;
     int flash_detected = 0;
     /* Search forward from the proposed arf/next gf position */
     for ( i = 0; i < f_frames; i++ )
     {
         if ( read_frame_stats(cpi, &this_frame, (i+offset)) == EOF )
             break;
         /* Update the motion related elements to the boost calculation */
         accumulate_frame_motion_stats( cpi, &this_frame,
             &this_frame_mv_in_out, &mv_in_out_accumulator,
             &abs_mv_in_out_accumulator, &mv_ratio_accumulator );
         /* Calculate the baseline boost number for this frame */
         r = calc_frame_boost( cpi, &this_frame, this_frame_mv_in_out );
         /* We want to discount the the flash frame itself and the recovery
          * frame that follows as both will have poor scores.
          */
         flash_detected = detect_flash(cpi, (i+offset)) ||
                          detect_flash(cpi, (i+offset+1));
         /* Cumulative effect of prediction quality decay */
         if ( !flash_detected )
         {
             decay_accumulator =
                 decay_accumulator *
                 get_prediction_decay_rate(cpi, &this_frame);
             decay_accumulator =
                 decay_accumulator < 0.1 ? 0.1 : decay_accumulator;
         }
         boost_score += (decay_accumulator * r);
         /* Break out conditions. */
         if  ( (!flash_detected) &&
               ((mv_ratio_accumulator > 100.0) ||
                (abs_mv_in_out_accumulator > 3.0) ||
                (mv_in_out_accumulator < -2.0) ) )
         {
             break;
         }
     }
     *f_boost = (int)(boost_score * 100.0) >> 4;
     /* Reset for backward looking loop */
     boost_score = 0.0;
     mv_ratio_accumulator = 0.0;
     decay_accumulator = 1.0;
     this_frame_mv_in_out = 0.0;
     mv_in_out_accumulator = 0.0;
     abs_mv_in_out_accumulator = 0.0;
     /* Search forward from the proposed arf/next gf position */
     for ( i = -1; i >= -b_frames; i-- )
     {
         if ( read_frame_stats(cpi, &this_frame, (i+offset)) == EOF )
             break;
         /* Update the motion related elements to the boost calculation */
         accumulate_frame_motion_stats( cpi, &this_frame,
             &this_frame_mv_in_out, &mv_in_out_accumulator,
             &abs_mv_in_out_accumulator, &mv_ratio_accumulator );
         /* Calculate the baseline boost number for this frame */
         r = calc_frame_boost( cpi, &this_frame, this_frame_mv_in_out );
         /* We want to discount the the flash frame itself and the recovery
          * frame that follows as both will have poor scores.
          */
         flash_detected = detect_flash(cpi, (i+offset)) ||
                          detect_flash(cpi, (i+offset+1));
         /* Cumulative effect of prediction quality decay */
         if ( !flash_detected )
         {
             decay_accumulator =
                 decay_accumulator *
                 get_prediction_decay_rate(cpi, &this_frame);
             decay_accumulator =
                 decay_accumulator < 0.1 ? 0.1 : decay_accumulator;
         }
         boost_score += (decay_accumulator * r);
         /* Break out conditions. */
         if  ( (!flash_detected) &&
               ((mv_ratio_accumulator > 100.0) ||
                (abs_mv_in_out_accumulator > 3.0) ||
                (mv_in_out_accumulator < -2.0) ) )
         {
             break;
         }
     }
     *b_boost = (int)(boost_score * 100.0) >> 4;
     return (*f_boost + *b_boost);
 }
 #endif
 /* Analyse and define a gf/arf group . */
 static void define_gf_group(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
 {
     FIRSTPASS_STATS next_frame;
     FIRSTPASS_STATS *start_pos;
     int i;
     double r;
     double boost_score = 0.0;
     double old_boost_score = 0.0;
     double gf_group_err = 0.0;
     double gf_first_frame_err = 0.0;
     double mod_frame_err = 0.0;
     double mv_ratio_accumulator = 0.0;
     double decay_accumulator = 1.0;
     double loop_decay_rate = 1.00;          /* Starting decay rate */
     double this_frame_mv_in_out = 0.0;
     double mv_in_out_accumulator = 0.0;
     double abs_mv_in_out_accumulator = 0.0;
     double mod_err_per_mb_accumulator = 0.0;
     int max_bits = frame_max_bits(cpi);     /* Max for a single frame */
     unsigned int allow_alt_ref =
                     cpi->oxcf.play_alternate && cpi->oxcf.lag_in_frames;
     int alt_boost = 0;
     int f_boost = 0;
     int b_boost = 0;
     int flash_detected;
     cpi->twopass.gf_group_bits = 0;
     cpi->twopass.gf_decay_rate = 0;
     vp8_clear_system_state();
     start_pos = cpi->twopass.stats_in;
     vpx_memset(&next_frame, 0, sizeof(next_frame)); /* assure clean */
     /* Load stats for the current frame. */
     mod_frame_err = calculate_modified_err(cpi, this_frame);
     /* Note the error of the frame at the start of the group (this will be
      * the GF frame error if we code a normal gf
      */
     gf_first_frame_err = mod_frame_err;
     /* Special treatment if the current frame is a key frame (which is also
      * a gf). If it is then its error score (and hence bit allocation) need
      * to be subtracted out from the calculation for the GF group
      */
     if (cpi->common.frame_type == KEY_FRAME)
         gf_group_err -= gf_first_frame_err;
     /* Scan forward to try and work out how many frames the next gf group
      * should contain and what level of boost is appropriate for the GF
      * or ARF that will be coded with the group
      */
     i = 0;
     while (((i < cpi->twopass.static_scene_max_gf_interval) ||
             ((cpi->twopass.frames_to_key - i) < MIN_GF_INTERVAL)) &&
            (i < cpi->twopass.frames_to_key))
     {
         i++;
         /* Accumulate error score of frames in this gf group */
         mod_frame_err = calculate_modified_err(cpi, this_frame);
         gf_group_err += mod_frame_err;
         mod_err_per_mb_accumulator +=
             mod_frame_err / DOUBLE_DIVIDE_CHECK((double)cpi->common.MBs);
         if (EOF == input_stats(cpi, &next_frame))
             break;
         /* Test for the case where there is a brief flash but the prediction
          * quality back to an earlier frame is then restored.
          */
         flash_detected = detect_flash(cpi, 0);
         /* Update the motion related elements to the boost calculation */
         accumulate_frame_motion_stats( cpi, &next_frame,
             &this_frame_mv_in_out, &mv_in_out_accumulator,
             &abs_mv_in_out_accumulator, &mv_ratio_accumulator );
         /* Calculate a baseline boost number for this frame */
         r = calc_frame_boost( cpi, &next_frame, this_frame_mv_in_out );
         /* Cumulative effect of prediction quality decay */
         if ( !flash_detected )
         {
             loop_decay_rate = get_prediction_decay_rate(cpi, &next_frame);
             decay_accumulator = decay_accumulator * loop_decay_rate;
             decay_accumulator =
                 decay_accumulator < 0.1 ? 0.1 : decay_accumulator;
         }
         boost_score += (decay_accumulator * r);
         /* Break clause to detect very still sections after motion
          * For example a staic image after a fade or other transition.
          */
         if ( detect_transition_to_still( cpi, i, 5,
                                          loop_decay_rate,
                                          decay_accumulator ) )
         {
             allow_alt_ref = 0;
             boost_score = old_boost_score;
             break;
         }
         /* Break out conditions. */
         if  (
             /* Break at cpi->max_gf_interval unless almost totally static */
             (i >= cpi->max_gf_interval && (decay_accumulator < 0.995)) ||
             (
                 /* Dont break out with a very short interval */
                 (i > MIN_GF_INTERVAL) &&
                 /* Dont break out very close to a key frame */
                 ((cpi->twopass.frames_to_key - i) >= MIN_GF_INTERVAL) &&
                 ((boost_score > 20.0) || (next_frame.pcnt_inter < 0.75)) &&
                 (!flash_detected) &&
                 ((mv_ratio_accumulator > 100.0) ||
                  (abs_mv_in_out_accumulator > 3.0) ||
                  (mv_in_out_accumulator < -2.0) ||
                  ((boost_score - old_boost_score) < 2.0))
             ) )
         {
             boost_score = old_boost_score;
             break;
         }
         vpx_memcpy(this_frame, &next_frame, sizeof(*this_frame));
         old_boost_score = boost_score;
     }
     cpi->twopass.gf_decay_rate =
         (i > 0) ? (int)(100.0 * (1.0 - decay_accumulator)) / i : 0;
     /* When using CBR apply additional buffer related upper limits */
     if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
     {
         double max_boost;
         /* For cbr apply buffer related limits */
         if (cpi->drop_frames_allowed)
         {
             int64_t df_buffer_level = cpi->oxcf.drop_frames_water_mark *
                                   (cpi->oxcf.optimal_buffer_level / 100);
             if (cpi->buffer_level > df_buffer_level)
                 max_boost = ((double)((cpi->buffer_level - df_buffer_level) * 2 / 3) * 16.0) / DOUBLE_DIVIDE_CHECK((double)cpi->av_per_frame_bandwidth);
             else
                 max_boost = 0.0;
         }
         else if (cpi->buffer_level > 0)
         {
             max_boost = ((double)(cpi->buffer_level * 2 / 3) * 16.0) / DOUBLE_DIVIDE_CHECK((double)cpi->av_per_frame_bandwidth);
         }
         else
         {
             max_boost = 0.0;
         }
         if (boost_score > max_boost)
             boost_score = max_boost;
     }
     /* Dont allow conventional gf too near the next kf */
     if ((cpi->twopass.frames_to_key - i) < MIN_GF_INTERVAL)
     {
         while (i < cpi->twopass.frames_to_key)
         {
             i++;
             if (EOF == input_stats(cpi, this_frame))
                 break;
             if (i < cpi->twopass.frames_to_key)
             {
                 mod_frame_err = calculate_modified_err(cpi, this_frame);
                 gf_group_err += mod_frame_err;
             }
         }
     }
     cpi->gfu_boost = (int)(boost_score * 100.0) >> 4;
 #if NEW_BOOST
     /* Alterrnative boost calculation for alt ref */
     alt_boost = calc_arf_boost( cpi, 0, (i-1), (i-1), &f_boost, &b_boost );
 #endif
     /* Should we use the alternate refernce frame */
     if (allow_alt_ref &&
         (i >= MIN_GF_INTERVAL) &&
         /* dont use ARF very near next kf */
         (i <= (cpi->twopass.frames_to_key - MIN_GF_INTERVAL)) &&
 #if NEW_BOOST
         ((next_frame.pcnt_inter > 0.75) ||
          (next_frame.pcnt_second_ref > 0.5)) &&
         ((mv_in_out_accumulator / (double)i > -0.2) ||
          (mv_in_out_accumulator > -2.0)) &&
         (b_boost > 100) &&
         (f_boost > 100) )
 #else
         (next_frame.pcnt_inter > 0.75) &&
         ((mv_in_out_accumulator / (double)i > -0.2) ||
          (mv_in_out_accumulator > -2.0)) &&
         (cpi->gfu_boost > 100) &&
         (cpi->twopass.gf_decay_rate <=
             (ARF_DECAY_THRESH + (cpi->gfu_boost / 200))) )
 #endif
     {
         int Boost;
         int allocation_chunks;
         int Q = (cpi->oxcf.fixed_q < 0)
                 ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q;
         int tmp_q;
         int arf_frame_bits = 0;
         int group_bits;
 #if NEW_BOOST
         cpi->gfu_boost = alt_boost;
 #endif
         /* Estimate the bits to be allocated to the group as a whole */
         if ((cpi->twopass.kf_group_bits > 0) &&
             (cpi->twopass.kf_group_error_left > 0))
         {
             group_bits = (int)((double)cpi->twopass.kf_group_bits *
                 (gf_group_err / (double)cpi->twopass.kf_group_error_left));
         }
         else
             group_bits = 0;
         /* Boost for arf frame */
 #if NEW_BOOST
         Boost = (alt_boost * GFQ_ADJUSTMENT) / 100;
 #else
         Boost = (cpi->gfu_boost * 3 * GFQ_ADJUSTMENT) / (2 * 100);
 #endif
         Boost += (i * 50);
         /* Set max and minimum boost and hence minimum allocation */
         if (Boost > ((cpi->baseline_gf_interval + 1) * 200))
             Boost = ((cpi->baseline_gf_interval + 1) * 200);
         else if (Boost < 125)
             Boost = 125;
         allocation_chunks = (i * 100) + Boost;
         /* Normalize Altboost and allocations chunck down to prevent overflow */
         while (Boost > 1000)
         {
             Boost /= 2;
             allocation_chunks /= 2;
         }
         /* Calculate the number of bits to be spent on the arf based on the
          * boost number
          */
         arf_frame_bits = (int)((double)Boost * (group_bits /
                                (double)allocation_chunks));
         /* Estimate if there are enough bits available to make worthwhile use
          * of an arf.
          */
         tmp_q = estimate_q(cpi, mod_frame_err, (int)arf_frame_bits);
         /* Only use an arf if it is likely we will be able to code
          * it at a lower Q than the surrounding frames.
          */
         if (tmp_q < cpi->worst_quality)
         {
             int half_gf_int;
             int frames_after_arf;
             int frames_bwd = cpi->oxcf.arnr_max_frames - 1;
             int frames_fwd = cpi->oxcf.arnr_max_frames - 1;
             cpi->source_alt_ref_pending = 1;
             /*
              * For alt ref frames the error score for the end frame of the
              * group (the alt ref frame) should not contribute to the group
              * total and hence the number of bit allocated to the group.
              * Rather it forms part of the next group (it is the GF at the
              * start of the next group)
              * gf_group_err -= mod_frame_err;
              *
              * For alt ref frames alt ref frame is technically part of the
              * GF frame for the next group but we always base the error
              * calculation and bit allocation on the current group of frames.
              *
              * Set the interval till the next gf or arf.
              * For ARFs this is the number of frames to be coded before the
              * future frame that is coded as an ARF.
              * The future frame itself is part of the next group
              */
             cpi->baseline_gf_interval = i;
             /*
              * Define the arnr filter width for this group of frames:
              * We only filter frames that lie within a distance of half
              * the GF interval from the ARF frame. We also have to trap
              * cases where the filter extends beyond the end of clip.
              * Note: this_frame->frame has been updated in the loop
              * so it now points at the ARF frame.
              */
             half_gf_int = cpi->baseline_gf_interval >> 1;
             frames_after_arf = (int)(cpi->twopass.total_stats.count -
                                this_frame->frame - 1);
             switch (cpi->oxcf.arnr_type)
             {
             case 1: /* Backward filter */
                 frames_fwd = 0;
                 if (frames_bwd > half_gf_int)
                     frames_bwd = half_gf_int;
                 break;
             case 2: /* Forward filter */
                 if (frames_fwd > half_gf_int)
                     frames_fwd = half_gf_int;
                 if (frames_fwd > frames_after_arf)
                     frames_fwd = frames_after_arf;
                 frames_bwd = 0;
                 break;
             case 3: /* Centered filter */
             default:
                 frames_fwd >>= 1;
                 if (frames_fwd > frames_after_arf)
                     frames_fwd = frames_after_arf;
                 if (frames_fwd > half_gf_int)
                     frames_fwd = half_gf_int;
                 frames_bwd = frames_fwd;
                 /* For even length filter there is one more frame backward
                  * than forward: e.g. len=6 ==> bbbAff, len=7 ==> bbbAfff.
                  */
                 if (frames_bwd < half_gf_int)
                     frames_bwd += (cpi->oxcf.arnr_max_frames+1) & 0x1;
                 break;
             }
             cpi->active_arnr_frames = frames_bwd + 1 + frames_fwd;
         }
         else
         {
             cpi->source_alt_ref_pending = 0;
             cpi->baseline_gf_interval = i;
         }
     }
     else
     {
         cpi->source_alt_ref_pending = 0;
         cpi->baseline_gf_interval = i;
     }
     /*
      * Now decide how many bits should be allocated to the GF group as  a
      * proportion of those remaining in the kf group.
      * The final key frame group in the clip is treated as a special case
      * where cpi->twopass.kf_group_bits is tied to cpi->twopass.bits_left.
      * This is also important for short clips where there may only be one
      * key frame.
      */
     if (cpi->twopass.frames_to_key >= (int)(cpi->twopass.total_stats.count -
                                             cpi->common.current_video_frame))
     {
         cpi->twopass.kf_group_bits =
             (cpi->twopass.bits_left > 0) ? cpi->twopass.bits_left : 0;
     }
     /* Calculate the bits to be allocated to the group as a whole */
     if ((cpi->twopass.kf_group_bits > 0) &&
         (cpi->twopass.kf_group_error_left > 0))
     {
         cpi->twopass.gf_group_bits =
             (int64_t)(cpi->twopass.kf_group_bits *
                       (gf_group_err / cpi->twopass.kf_group_error_left));
     }
     else
         cpi->twopass.gf_group_bits = 0;
     cpi->twopass.gf_group_bits =
         (cpi->twopass.gf_group_bits < 0)
             ? 0
             : (cpi->twopass.gf_group_bits > cpi->twopass.kf_group_bits)
                 ? cpi->twopass.kf_group_bits : cpi->twopass.gf_group_bits;
     /* Clip cpi->twopass.gf_group_bits based on user supplied data rate
      * variability limit (cpi->oxcf.two_pass_vbrmax_section)
      */
     if (cpi->twopass.gf_group_bits >
         (int64_t)max_bits * cpi->baseline_gf_interval)
         cpi->twopass.gf_group_bits =
             (int64_t)max_bits * cpi->baseline_gf_interval;
     /* Reset the file position */
     reset_fpf_position(cpi, start_pos);
     /* Update the record of error used so far (only done once per gf group) */
     cpi->twopass.modified_error_used += gf_group_err;
     /* Assign  bits to the arf or gf. */
     for (i = 0; i <= (cpi->source_alt_ref_pending && cpi->common.frame_type != KEY_FRAME); i++) {
         int Boost;
         int allocation_chunks;
         int Q = (cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q;
         int gf_bits;
         /* For ARF frames */
         if (cpi->source_alt_ref_pending && i == 0)
         {
 #if NEW_BOOST
             Boost = (alt_boost * GFQ_ADJUSTMENT) / 100;
 #else
             Boost = (cpi->gfu_boost * 3 * GFQ_ADJUSTMENT) / (2 * 100);
 #endif
             Boost += (cpi->baseline_gf_interval * 50);
             /* Set max and minimum boost and hence minimum allocation */
             if (Boost > ((cpi->baseline_gf_interval + 1) * 200))
                 Boost = ((cpi->baseline_gf_interval + 1) * 200);
             else if (Boost < 125)
                 Boost = 125;
             allocation_chunks =
                 ((cpi->baseline_gf_interval + 1) * 100) + Boost;
         }
         /* Else for standard golden frames */
         else
         {
             /* boost based on inter / intra ratio of subsequent frames */
             Boost = (cpi->gfu_boost * GFQ_ADJUSTMENT) / 100;
             /* Set max and minimum boost and hence minimum allocation */
             if (Boost > (cpi->baseline_gf_interval * 150))
                 Boost = (cpi->baseline_gf_interval * 150);
             else if (Boost < 125)
                 Boost = 125;
             allocation_chunks =
                 (cpi->baseline_gf_interval * 100) + (Boost - 100);
         }
         /* Normalize Altboost and allocations chunck down to prevent overflow */
         while (Boost > 1000)
         {
             Boost /= 2;
             allocation_chunks /= 2;
         }
         /* Calculate the number of bits to be spent on the gf or arf based on
          * the boost number
          */
         gf_bits = (int)((double)Boost *
                         (cpi->twopass.gf_group_bits /
                          (double)allocation_chunks));
         /* If the frame that is to be boosted is simpler than the average for
          * the gf/arf group then use an alternative calculation
          * based on the error score of the frame itself
          */
         if (mod_frame_err < gf_group_err / (double)cpi->baseline_gf_interval)
         {
             double  alt_gf_grp_bits;
             int     alt_gf_bits;
             alt_gf_grp_bits =
                 (double)cpi->twopass.kf_group_bits  *
                 (mod_frame_err * (double)cpi->baseline_gf_interval) /
                 DOUBLE_DIVIDE_CHECK((double)cpi->twopass.kf_group_error_left);
             alt_gf_bits = (int)((double)Boost * (alt_gf_grp_bits /
                                                  (double)allocation_chunks));
             if (gf_bits > alt_gf_bits)
             {
                 gf_bits = alt_gf_bits;
             }
         }
         /* Else if it is harder than other frames in the group make sure it at
          * least receives an allocation in keeping with its relative error
          * score, otherwise it may be worse off than an "un-boosted" frame
          */
         else
         {
             int alt_gf_bits =
                 (int)((double)cpi->twopass.kf_group_bits *
                       mod_frame_err /
                       DOUBLE_DIVIDE_CHECK((double)cpi->twopass.kf_group_error_left));
             if (alt_gf_bits > gf_bits)
             {
                 gf_bits = alt_gf_bits;
             }
         }
         /* Apply an additional limit for CBR */
         if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
         {
             if (cpi->twopass.gf_bits > (int)(cpi->buffer_level >> 1))
                 cpi->twopass.gf_bits = (int)(cpi->buffer_level >> 1);
         }
         /* Dont allow a negative value for gf_bits */
         if (gf_bits < 0)
             gf_bits = 0;
         /* Add in minimum for a frame */
         gf_bits += cpi->min_frame_bandwidth;
         if (i == 0)
         {
             cpi->twopass.gf_bits = gf_bits;
         }
         if (i == 1 || (!cpi->source_alt_ref_pending && (cpi->common.frame_type != KEY_FRAME)))
         {
             /* Per frame bit target for this frame */
             cpi->per_frame_bandwidth = gf_bits;
         }
     }
     {
         /* Adjust KF group bits and error remainin */
         cpi->twopass.kf_group_error_left -= (int64_t)gf_group_err;
         cpi->twopass.kf_group_bits -= cpi->twopass.gf_group_bits;
         if (cpi->twopass.kf_group_bits < 0)
             cpi->twopass.kf_group_bits = 0;
         /* Note the error score left in the remaining frames of the group.
          * For normal GFs we want to remove the error score for the first
          * frame of the group (except in Key frame case where this has
          * already happened)
          */
         if (!cpi->source_alt_ref_pending && cpi->common.frame_type != KEY_FRAME)
             cpi->twopass.gf_group_error_left = (int)(gf_group_err -
                                                      gf_first_frame_err);
         else
             cpi->twopass.gf_group_error_left = (int) gf_group_err;
         cpi->twopass.gf_group_bits -= cpi->twopass.gf_bits - cpi->min_frame_bandwidth;
         if (cpi->twopass.gf_group_bits < 0)
             cpi->twopass.gf_group_bits = 0;
         /* This condition could fail if there are two kfs very close together
          * despite (MIN_GF_INTERVAL) and would cause a devide by 0 in the
          * calculation of cpi->twopass.alt_extra_bits.
          */
         if ( cpi->baseline_gf_interval >= 3 )
         {
 #if NEW_BOOST
             int boost = (cpi->source_alt_ref_pending)
                         ? b_boost : cpi->gfu_boost;
 #else
             int boost = cpi->gfu_boost;
 #endif
             if ( boost >= 150 )
             {
                 int pct_extra;
                 pct_extra = (boost - 100) / 50;
                 pct_extra = (pct_extra > 20) ? 20 : pct_extra;
                 cpi->twopass.alt_extra_bits =
                     (cpi->twopass.gf_group_bits * pct_extra) / 100;
                 cpi->twopass.gf_group_bits -= cpi->twopass.alt_extra_bits;
                 cpi->twopass.alt_extra_bits /=
                     ((cpi->baseline_gf_interval-1)>>1);
             }
             else
                 cpi->twopass.alt_extra_bits = 0;
         }
         else
             cpi->twopass.alt_extra_bits = 0;
     }
     /* Adjustments based on a measure of complexity of the section */
     if (cpi->common.frame_type != KEY_FRAME)
     {
         FIRSTPASS_STATS sectionstats;
         double Ratio;
         zero_stats(&sectionstats);
         reset_fpf_position(cpi, start_pos);
         for (i = 0 ; i < cpi->baseline_gf_interval ; i++)
         {
             input_stats(cpi, &next_frame);
             accumulate_stats(&sectionstats, &next_frame);
         }
         avg_stats(&sectionstats);
         cpi->twopass.section_intra_rating = (unsigned int)
             (sectionstats.intra_error /
             DOUBLE_DIVIDE_CHECK(sectionstats.coded_error));
         Ratio = sectionstats.intra_error / DOUBLE_DIVIDE_CHECK(sectionstats.coded_error);
         cpi->twopass.section_max_qfactor = 1.0 - ((Ratio - 10.0) * 0.025);
         if (cpi->twopass.section_max_qfactor < 0.80)
             cpi->twopass.section_max_qfactor = 0.80;
         reset_fpf_position(cpi, start_pos);
     }
 }
 /* Allocate bits to a normal frame that is neither a gf an arf or a key frame. */
 static void assign_std_frame_bits(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
 {
     int    target_frame_size;
     double modified_err;
     double err_fraction;
     int max_bits = frame_max_bits(cpi);  /* Max for a single frame */
     /* Calculate modified prediction error used in bit allocation */
     modified_err = calculate_modified_err(cpi, this_frame);
     /* What portion of the remaining GF group error is used by this frame */
     if (cpi->twopass.gf_group_error_left > 0)
         err_fraction = modified_err / cpi->twopass.gf_group_error_left;
     else
         err_fraction = 0.0;
     /* How many of those bits available for allocation should we give it? */
     target_frame_size = (int)((double)cpi->twopass.gf_group_bits * err_fraction);
     /* Clip to target size to 0 - max_bits (or cpi->twopass.gf_group_bits)
      * at the top end.
      */
     if (target_frame_size < 0)
         target_frame_size = 0;
     else
     {
         if (target_frame_size > max_bits)
             target_frame_size = max_bits;
         if (target_frame_size > cpi->twopass.gf_group_bits)
             target_frame_size = cpi->twopass.gf_group_bits;
     }
     /* Adjust error and bits remaining */
     cpi->twopass.gf_group_error_left -= (int)modified_err;
     cpi->twopass.gf_group_bits -= target_frame_size;
     if (cpi->twopass.gf_group_bits < 0)
         cpi->twopass.gf_group_bits = 0;
     /* Add in the minimum number of bits that is set aside for every frame. */
     target_frame_size += cpi->min_frame_bandwidth;
     /* Every other frame gets a few extra bits */
     if ( (cpi->frames_since_golden & 0x01) &&
          (cpi->frames_till_gf_update_due > 0) )
     {
         target_frame_size += cpi->twopass.alt_extra_bits;
     }
     /* Per frame bit target for this frame */
     cpi->per_frame_bandwidth = target_frame_size;
 }
 void vp8_second_pass(VP8_COMP *cpi)
 {
     int tmp_q;
     int frames_left = (int)(cpi->twopass.total_stats.count - cpi->common.current_video_frame);
     FIRSTPASS_STATS this_frame = {0};
     FIRSTPASS_STATS this_frame_copy;
     double this_frame_intra_error;
     double this_frame_coded_error;
     int overhead_bits;
     if (!cpi->twopass.stats_in)
     {
         return ;
     }
     vp8_clear_system_state();
     if (EOF == input_stats(cpi, &this_frame))
         return;
     this_frame_intra_error = this_frame.intra_error;
     this_frame_coded_error = this_frame.coded_error;
     /* keyframe and section processing ! */
     if (cpi->twopass.frames_to_key == 0)
     {
         /* Define next KF group and assign bits to it */
         vpx_memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
         find_next_key_frame(cpi, &this_frame_copy);
         /* Special case: Error error_resilient_mode mode does not make much
          * sense for two pass but with its current meaning but this code is
          * designed to stop outlandish behaviour if someone does set it when
          * using two pass. It effectively disables GF groups. This is
          * temporary code till we decide what should really happen in this
          * case.
          */
         if (cpi->oxcf.error_resilient_mode)
         {
             cpi->twopass.gf_group_bits = cpi->twopass.kf_group_bits;
             cpi->twopass.gf_group_error_left =
                                   (int)cpi->twopass.kf_group_error_left;
             cpi->baseline_gf_interval = cpi->twopass.frames_to_key;
             cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
             cpi->source_alt_ref_pending = 0;
         }
     }
     /* Is this a GF / ARF (Note that a KF is always also a GF) */
     if (cpi->frames_till_gf_update_due == 0)
     {
         /* Define next gf group and assign bits to it */
         vpx_memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
         define_gf_group(cpi, &this_frame_copy);
         /* If we are going to code an altref frame at the end of the group
          * and the current frame is not a key frame.... If the previous
          * group used an arf this frame has already benefited from that arf
          * boost and it should not be given extra bits If the previous
          * group was NOT coded using arf we may want to apply some boost to
          * this GF as well
          */
         if (cpi->source_alt_ref_pending && (cpi->common.frame_type != KEY_FRAME))
         {
             /* Assign a standard frames worth of bits from those allocated
              * to the GF group
              */
             int bak = cpi->per_frame_bandwidth;
             vpx_memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
             assign_std_frame_bits(cpi, &this_frame_copy);
             cpi->per_frame_bandwidth = bak;
         }
     }
     /* Otherwise this is an ordinary frame */
     else
     {
         /* Special case: Error error_resilient_mode mode does not make much
          * sense for two pass but with its current meaning but this code is
          * designed to stop outlandish behaviour if someone does set it
          * when using two pass. It effectively disables GF groups. This is
          * temporary code till we decide what should really happen in this
          * case.
          */
         if (cpi->oxcf.error_resilient_mode)
         {
             cpi->frames_till_gf_update_due = cpi->twopass.frames_to_key;
             if (cpi->common.frame_type != KEY_FRAME)
             {
                 /* Assign bits from those allocated to the GF group */
                 vpx_memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
                 assign_std_frame_bits(cpi, &this_frame_copy);
             }
         }
         else
         {
             /* Assign bits from those allocated to the GF group */
             vpx_memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
             assign_std_frame_bits(cpi, &this_frame_copy);
         }
     }
     /* Keep a globally available copy of this and the next frame's iiratio. */
     cpi->twopass.this_iiratio = (unsigned int)(this_frame_intra_error /
                         DOUBLE_DIVIDE_CHECK(this_frame_coded_error));
     {
         FIRSTPASS_STATS next_frame;
         if ( lookup_next_frame_stats(cpi, &next_frame) != EOF )
         {
             cpi->twopass.next_iiratio = (unsigned int)(next_frame.intra_error /
                                 DOUBLE_DIVIDE_CHECK(next_frame.coded_error));
         }
     }
     /* Set nominal per second bandwidth for this frame */
     cpi->target_bandwidth = (int)
     (cpi->per_frame_bandwidth * cpi->output_framerate);
     if (cpi->target_bandwidth < 0)
         cpi->target_bandwidth = 0;
     /* Account for mv, mode and other overheads. */
     overhead_bits = (int)estimate_modemvcost(
                         cpi, &cpi->twopass.total_left_stats );
     /* Special case code for first frame. */
     if (cpi->common.current_video_frame == 0)
     {
         cpi->twopass.est_max_qcorrection_factor = 1.0;
         /* Set a cq_level in constrained quality mode. */
         if ( cpi->oxcf.end_usage == USAGE_CONSTRAINED_QUALITY )
         {
             int est_cq;
             est_cq =
                 estimate_cq( cpi,
                              &cpi->twopass.total_left_stats,
                              (int)(cpi->twopass.bits_left / frames_left),
                              overhead_bits );
             cpi->cq_target_quality = cpi->oxcf.cq_level;
             if ( est_cq > cpi->cq_target_quality )
                 cpi->cq_target_quality = est_cq;
         }
         /* guess at maxq needed in 2nd pass */
         cpi->twopass.maxq_max_limit = cpi->worst_quality;
         cpi->twopass.maxq_min_limit = cpi->best_quality;
         tmp_q = estimate_max_q(
                     cpi,
                     &cpi->twopass.total_left_stats,
                     (int)(cpi->twopass.bits_left / frames_left),
                     overhead_bits );
         /* Limit the maxq value returned subsequently.
          * This increases the risk of overspend or underspend if the initial
          * estimate for the clip is bad, but helps prevent excessive
          * variation in Q, especially near the end of a clip
          * where for example a small overspend may cause Q to crash
          */
         cpi->twopass.maxq_max_limit = ((tmp_q + 32) < cpi->worst_quality)
                                   ? (tmp_q + 32) : cpi->worst_quality;
         cpi->twopass.maxq_min_limit = ((tmp_q - 32) > cpi->best_quality)
                                   ? (tmp_q - 32) : cpi->best_quality;
         cpi->active_worst_quality         = tmp_q;
         cpi->ni_av_qi                     = tmp_q;
     }
     /* The last few frames of a clip almost always have to few or too many
      * bits and for the sake of over exact rate control we dont want to make
      * radical adjustments to the allowed quantizer range just to use up a
      * few surplus bits or get beneath the target rate.
      */
     else if ( (cpi->common.current_video_frame <
                  (((unsigned int)cpi->twopass.total_stats.count * 255)>>8)) &&
               ((cpi->common.current_video_frame + cpi->baseline_gf_interval) <
                  (unsigned int)cpi->twopass.total_stats.count) )
     {
         if (frames_left < 1)
             frames_left = 1;
         tmp_q = estimate_max_q(
                     cpi,
                     &cpi->twopass.total_left_stats,
                     (int)(cpi->twopass.bits_left / frames_left),
                     overhead_bits );
         /* Move active_worst_quality but in a damped way */
         if (tmp_q > cpi->active_worst_quality)
             cpi->active_worst_quality ++;
         else if (tmp_q < cpi->active_worst_quality)
             cpi->active_worst_quality --;
         cpi->active_worst_quality =
             ((cpi->active_worst_quality * 3) + tmp_q + 2) / 4;
     }
     cpi->twopass.frames_to_key --;
     /* Update the total stats remaining sturcture */
     subtract_stats(&cpi->twopass.total_left_stats, &this_frame );
 }
 static int test_candidate_kf(VP8_COMP *cpi,  FIRSTPASS_STATS *last_frame, FIRSTPASS_STATS *this_frame, FIRSTPASS_STATS *next_frame)
 {
     int is_viable_kf = 0;
     /* Does the frame satisfy the primary criteria of a key frame
      *      If so, then examine how well it predicts subsequent frames
      */
     if ((this_frame->pcnt_second_ref < 0.10) &&
         (next_frame->pcnt_second_ref < 0.10) &&
         ((this_frame->pcnt_inter < 0.05) ||
          (
              ((this_frame->pcnt_inter - this_frame->pcnt_neutral) < .25) &&
              ((this_frame->intra_error / DOUBLE_DIVIDE_CHECK(this_frame->coded_error)) < 2.5) &&
              ((fabs(last_frame->coded_error - this_frame->coded_error) / DOUBLE_DIVIDE_CHECK(this_frame->coded_error) > .40) ||
               (fabs(last_frame->intra_error - this_frame->intra_error) / DOUBLE_DIVIDE_CHECK(this_frame->intra_error) > .40) ||
               ((next_frame->intra_error / DOUBLE_DIVIDE_CHECK(next_frame->coded_error)) > 3.5)
              )
          )
         )
        )
     {
         int i;
         FIRSTPASS_STATS *start_pos;
         FIRSTPASS_STATS local_next_frame;
         double boost_score = 0.0;
         double old_boost_score = 0.0;
         double decay_accumulator = 1.0;
         double next_iiratio;
         vpx_memcpy(&local_next_frame, next_frame, sizeof(*next_frame));
         /* Note the starting file position so we can reset to it */
         start_pos = cpi->twopass.stats_in;
         /* Examine how well the key frame predicts subsequent frames */
         for (i = 0 ; i < 16; i++)
         {
             next_iiratio = (IIKFACTOR1 * local_next_frame.intra_error / DOUBLE_DIVIDE_CHECK(local_next_frame.coded_error)) ;
             if (next_iiratio > RMAX)
                 next_iiratio = RMAX;
             /* Cumulative effect of decay in prediction quality */
             if (local_next_frame.pcnt_inter > 0.85)
                 decay_accumulator = decay_accumulator * local_next_frame.pcnt_inter;
             else
                 decay_accumulator = decay_accumulator * ((0.85 + local_next_frame.pcnt_inter) / 2.0);
             /* Keep a running total */
             boost_score += (decay_accumulator * next_iiratio);
             /* Test various breakout clauses */
             if ((local_next_frame.pcnt_inter < 0.05) ||
                 (next_iiratio < 1.5) ||
                 (((local_next_frame.pcnt_inter -
                    local_next_frame.pcnt_neutral) < 0.20) &&
                  (next_iiratio < 3.0)) ||
                 ((boost_score - old_boost_score) < 0.5) ||
                 (local_next_frame.intra_error < 200)
                )
             {
                 break;
             }
             old_boost_score = boost_score;
             /* Get the next frame details */
             if (EOF == input_stats(cpi, &local_next_frame))
                 break;
         }
         /* If there is tolerable prediction for at least the next 3 frames
          * then break out else discard this pottential key frame and move on
          */
         if (boost_score > 5.0 && (i > 3))
             is_viable_kf = 1;
         else
         {
             /* Reset the file position */
             reset_fpf_position(cpi, start_pos);
             is_viable_kf = 0;
         }
     }
     return is_viable_kf;
 }
 static void find_next_key_frame(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
 {
     int i,j;
     FIRSTPASS_STATS last_frame;
     FIRSTPASS_STATS first_frame;
     FIRSTPASS_STATS next_frame;
     FIRSTPASS_STATS *start_position;
     double decay_accumulator = 1.0;
     double boost_score = 0;
     double old_boost_score = 0.0;
     double loop_decay_rate;
     double kf_mod_err = 0.0;
     double kf_group_err = 0.0;
     double kf_group_intra_err = 0.0;
     double kf_group_coded_err = 0.0;
     double recent_loop_decay[8] = {1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0};
     vpx_memset(&next_frame, 0, sizeof(next_frame));
     vp8_clear_system_state();
     start_position = cpi->twopass.stats_in;
     cpi->common.frame_type = KEY_FRAME;
     /* is this a forced key frame by interval */
     cpi->this_key_frame_forced = cpi->next_key_frame_forced;
     /* Clear the alt ref active flag as this can never be active on a key
      * frame
      */
     cpi->source_alt_ref_active = 0;
     /* Kf is always a gf so clear frames till next gf counter */
     cpi->frames_till_gf_update_due = 0;
     cpi->twopass.frames_to_key = 1;
     /* Take a copy of the initial frame details */
     vpx_memcpy(&first_frame, this_frame, sizeof(*this_frame));
     cpi->twopass.kf_group_bits = 0;
     cpi->twopass.kf_group_error_left = 0;
     kf_mod_err = calculate_modified_err(cpi, this_frame);
     /* find the next keyframe */
     i = 0;
     while (cpi->twopass.stats_in < cpi->twopass.stats_in_end)
     {
         /* Accumulate kf group error */
         kf_group_err += calculate_modified_err(cpi, this_frame);
         /* These figures keep intra and coded error counts for all frames
          * including key frames in the group. The effect of the key frame
          * itself can be subtracted out using the first_frame data
          * collected above
          */
         kf_group_intra_err += this_frame->intra_error;
         kf_group_coded_err += this_frame->coded_error;
         /* load a the next frame's stats */
         vpx_memcpy(&last_frame, this_frame, sizeof(*this_frame));
         input_stats(cpi, this_frame);
         /* Provided that we are not at the end of the file... */
         if (cpi->oxcf.auto_key
             && lookup_next_frame_stats(cpi, &next_frame) != EOF)
         {
             /* Normal scene cut check */
             if ( ( i >= MIN_GF_INTERVAL ) &&
                  test_candidate_kf(cpi, &last_frame, this_frame, &next_frame) )
             {
                 break;
             }
             /* How fast is prediction quality decaying */
             loop_decay_rate = get_prediction_decay_rate(cpi, &next_frame);
             /* We want to know something about the recent past... rather than
              * as used elsewhere where we are concened with decay in prediction
              * quality since the last GF or KF.
              */
             recent_loop_decay[i%8] = loop_decay_rate;
             decay_accumulator = 1.0;
             for (j = 0; j < 8; j++)
             {
                 decay_accumulator = decay_accumulator * recent_loop_decay[j];
             }
             /* Special check for transition or high motion followed by a
              * static scene.
              */
             if ( detect_transition_to_still( cpi, i,
                                              (cpi->key_frame_frequency-i),
                                              loop_decay_rate,
                                              decay_accumulator ) )
             {
                 break;
             }
             /* Step on to the next frame */
             cpi->twopass.frames_to_key ++;
             /* If we don't have a real key frame within the next two
              * forcekeyframeevery intervals then break out of the loop.
              */
             if (cpi->twopass.frames_to_key >= 2 *(int)cpi->key_frame_frequency)
                 break;
         } else
             cpi->twopass.frames_to_key ++;
         i++;
     }
     /* If there is a max kf interval set by the user we must obey it.
      * We already breakout of the loop above at 2x max.
      * This code centers the extra kf if the actual natural
      * interval is between 1x and 2x
      */
     if (cpi->oxcf.auto_key
         && cpi->twopass.frames_to_key > (int)cpi->key_frame_frequency )
     {
         FIRSTPASS_STATS *current_pos = cpi->twopass.stats_in;
         FIRSTPASS_STATS tmp_frame;
         cpi->twopass.frames_to_key /= 2;
         /* Copy first frame details */
         vpx_memcpy(&tmp_frame, &first_frame, sizeof(first_frame));
         /* Reset to the start of the group */
         reset_fpf_position(cpi, start_position);
         kf_group_err = 0;
         kf_group_intra_err = 0;
         kf_group_coded_err = 0;
         /* Rescan to get the correct error data for the forced kf group */
         for( i = 0; i < cpi->twopass.frames_to_key; i++ )
         {
             /* Accumulate kf group errors */
             kf_group_err += calculate_modified_err(cpi, &tmp_frame);
             kf_group_intra_err += tmp_frame.intra_error;
             kf_group_coded_err += tmp_frame.coded_error;
             /* Load a the next frame's stats */
             input_stats(cpi, &tmp_frame);
         }
         /* Reset to the start of the group */
         reset_fpf_position(cpi, current_pos);
         cpi->next_key_frame_forced = 1;
     }
     else
         cpi->next_key_frame_forced = 0;
     /* Special case for the last frame of the file */
     if (cpi->twopass.stats_in >= cpi->twopass.stats_in_end)
     {
         /* Accumulate kf group error */
         kf_group_err += calculate_modified_err(cpi, this_frame);
         /* These figures keep intra and coded error counts for all frames
          * including key frames in the group. The effect of the key frame
          * itself can be subtracted out using the first_frame data
          * collected above
          */
         kf_group_intra_err += this_frame->intra_error;
         kf_group_coded_err += this_frame->coded_error;
     }
     /* Calculate the number of bits that should be assigned to the kf group. */
     if ((cpi->twopass.bits_left > 0) && (cpi->twopass.modified_error_left > 0.0))
     {
         /* Max for a single normal frame (not key frame) */
         int max_bits = frame_max_bits(cpi);
         /* Maximum bits for the kf group */
         int64_t max_grp_bits;
         /* Default allocation based on bits left and relative
          * complexity of the section
          */
         cpi->twopass.kf_group_bits = (int64_t)( cpi->twopass.bits_left *
                                           ( kf_group_err /
                                             cpi->twopass.modified_error_left ));
         /* Clip based on maximum per frame rate defined by the user. */
         max_grp_bits = (int64_t)max_bits * (int64_t)cpi->twopass.frames_to_key;
         if (cpi->twopass.kf_group_bits > max_grp_bits)
             cpi->twopass.kf_group_bits = max_grp_bits;
         /* Additional special case for CBR if buffer is getting full. */
         if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
         {
             int64_t opt_buffer_lvl = cpi->oxcf.optimal_buffer_level;
             int64_t buffer_lvl = cpi->buffer_level;
             /* If the buffer is near or above the optimal and this kf group is
              * not being allocated much then increase the allocation a bit.
              */
             if (buffer_lvl >= opt_buffer_lvl)
             {
                 int64_t high_water_mark = (opt_buffer_lvl +
                                        cpi->oxcf.maximum_buffer_size) >> 1;
                 int64_t av_group_bits;
                 /* Av bits per frame * number of frames */
                 av_group_bits = (int64_t)cpi->av_per_frame_bandwidth *
                                 (int64_t)cpi->twopass.frames_to_key;
                 /* We are at or above the maximum. */
                 if (cpi->buffer_level >= high_water_mark)
                 {
                     int64_t min_group_bits;
                     min_group_bits = av_group_bits +
                                      (int64_t)(buffer_lvl -
                                                  high_water_mark);
                     if (cpi->twopass.kf_group_bits < min_group_bits)
                         cpi->twopass.kf_group_bits = min_group_bits;
                 }
                 /* We are above optimal but below the maximum */
                 else if (cpi->twopass.kf_group_bits < av_group_bits)
                 {
                     int64_t bits_below_av = av_group_bits -
                                               cpi->twopass.kf_group_bits;
                     cpi->twopass.kf_group_bits +=
                        (int64_t)((double)bits_below_av *
                                    (double)(buffer_lvl - opt_buffer_lvl) /
                                    (double)(high_water_mark - opt_buffer_lvl));
                 }
             }
         }
     }
     else
         cpi->twopass.kf_group_bits = 0;
     /* Reset the first pass file position */
     reset_fpf_position(cpi, start_position);
     /* determine how big to make this keyframe based on how well the
      * subsequent frames use inter blocks
      */
     decay_accumulator = 1.0;
     boost_score = 0.0;
     loop_decay_rate = 1.00;       /* Starting decay rate */
     for (i = 0 ; i < cpi->twopass.frames_to_key ; i++)
     {
         double r;
         if (EOF == input_stats(cpi, &next_frame))
             break;
         if (next_frame.intra_error > cpi->twopass.kf_intra_err_min)
             r = (IIKFACTOR2 * next_frame.intra_error /
                      DOUBLE_DIVIDE_CHECK(next_frame.coded_error));
         else
             r = (IIKFACTOR2 * cpi->twopass.kf_intra_err_min /
                      DOUBLE_DIVIDE_CHECK(next_frame.coded_error));
         if (r > RMAX)
             r = RMAX;
         /* How fast is prediction quality decaying */
         loop_decay_rate = get_prediction_decay_rate(cpi, &next_frame);
         decay_accumulator = decay_accumulator * loop_decay_rate;
         decay_accumulator = decay_accumulator < 0.1 ? 0.1 : decay_accumulator;
         boost_score += (decay_accumulator * r);
         if ((i > MIN_GF_INTERVAL) &&
             ((boost_score - old_boost_score) < 1.0))
         {
             break;
         }
         old_boost_score = boost_score;
     }
     if (1)
     {
         FIRSTPASS_STATS sectionstats;
         double Ratio;
         zero_stats(&sectionstats);
         reset_fpf_position(cpi, start_position);
         for (i = 0 ; i < cpi->twopass.frames_to_key ; i++)
         {
             input_stats(cpi, &next_frame);
             accumulate_stats(&sectionstats, &next_frame);
         }
         avg_stats(&sectionstats);
         cpi->twopass.section_intra_rating = (unsigned int)
             (sectionstats.intra_error
             / DOUBLE_DIVIDE_CHECK(sectionstats.coded_error));
         Ratio = sectionstats.intra_error / DOUBLE_DIVIDE_CHECK(sectionstats.coded_error);
         cpi->twopass.section_max_qfactor = 1.0 - ((Ratio - 10.0) * 0.025);
         if (cpi->twopass.section_max_qfactor < 0.80)
             cpi->twopass.section_max_qfactor = 0.80;
     }
     /* When using CBR apply additional buffer fullness related upper limits */
     if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
     {
         double max_boost;
         if (cpi->drop_frames_allowed)
         {
             int df_buffer_level = (int)(cpi->oxcf.drop_frames_water_mark
                                   * (cpi->oxcf.optimal_buffer_level / 100));
             if (cpi->buffer_level > df_buffer_level)
                 max_boost = ((double)((cpi->buffer_level - df_buffer_level) * 2 / 3) * 16.0) / DOUBLE_DIVIDE_CHECK((double)cpi->av_per_frame_bandwidth);
             else
                 max_boost = 0.0;
         }
         else if (cpi->buffer_level > 0)
         {
             max_boost = ((double)(cpi->buffer_level * 2 / 3) * 16.0) / DOUBLE_DIVIDE_CHECK((double)cpi->av_per_frame_bandwidth);
         }
         else
         {
             max_boost = 0.0;
         }
         if (boost_score > max_boost)
             boost_score = max_boost;
     }
     /* Reset the first pass file position */
     reset_fpf_position(cpi, start_position);
     /* Work out how many bits to allocate for the key frame itself */
     if (1)
     {
         int kf_boost = (int)boost_score;
         int allocation_chunks;
         int Counter = cpi->twopass.frames_to_key;
         int alt_kf_bits;
         YV12_BUFFER_CONFIG *lst_yv12 = &cpi->common.yv12_fb[cpi->common.lst_fb_idx];
         /* Min boost based on kf interval */
 #if 0
         while ((kf_boost < 48) && (Counter > 0))
         {
             Counter -= 2;
             kf_boost ++;
         }
 #endif
         if (kf_boost < 48)
         {
             kf_boost += ((Counter + 1) >> 1);
             if (kf_boost > 48) kf_boost = 48;
         }
         /* bigger frame sizes need larger kf boosts, smaller frames smaller
          * boosts...
          */
         if ((lst_yv12->y_width * lst_yv12->y_height) > (320 * 240))
             kf_boost += 2 * (lst_yv12->y_width * lst_yv12->y_height) / (320 * 240);
         else if ((lst_yv12->y_width * lst_yv12->y_height) < (320 * 240))
             kf_boost -= 4 * (320 * 240) / (lst_yv12->y_width * lst_yv12->y_height);
         /* Min KF boost */
         kf_boost = (int)((double)kf_boost * 100.0) >> 4; /* Scale 16 to 100 */
         if (kf_boost < 250)
             kf_boost = 250;
         /*
          * We do three calculations for kf size.
          * The first is based on the error score for the whole kf group.
          * The second (optionaly) on the key frames own error if this is
          * smaller than the average for the group.
          * The final one insures that the frame receives at least the
          * allocation it would have received based on its own error score vs
          * the error score remaining
          * Special case if the sequence appears almost totaly static
          * as measured by the decay accumulator. In this case we want to
          * spend almost all of the bits on the key frame.
          * cpi->twopass.frames_to_key-1 because key frame itself is taken
          * care of by kf_boost.
          */
         if ( decay_accumulator >= 0.99 )
         {
             allocation_chunks =
                 ((cpi->twopass.frames_to_key - 1) * 10) + kf_boost;
         }
         else
         {
             allocation_chunks =
                 ((cpi->twopass.frames_to_key - 1) * 100) + kf_boost;
         }
         /* Normalize Altboost and allocations chunck down to prevent overflow */
         while (kf_boost > 1000)
         {
             kf_boost /= 2;
             allocation_chunks /= 2;
         }
         cpi->twopass.kf_group_bits = (cpi->twopass.kf_group_bits < 0) ? 0 : cpi->twopass.kf_group_bits;
         /* Calculate the number of bits to be spent on the key frame */
         cpi->twopass.kf_bits  = (int)((double)kf_boost * ((double)cpi->twopass.kf_group_bits / (double)allocation_chunks));
         /* Apply an additional limit for CBR */
         if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
         {
             if (cpi->twopass.kf_bits > (int)((3 * cpi->buffer_level) >> 2))
                 cpi->twopass.kf_bits = (int)((3 * cpi->buffer_level) >> 2);
         }
         /* If the key frame is actually easier than the average for the
          * kf group (which does sometimes happen... eg a blank intro frame)
          * Then use an alternate calculation based on the kf error score
          * which should give a smaller key frame.
          */
         if (kf_mod_err < kf_group_err / cpi->twopass.frames_to_key)
         {
             double  alt_kf_grp_bits =
                         ((double)cpi->twopass.bits_left *
                          (kf_mod_err * (double)cpi->twopass.frames_to_key) /
                          DOUBLE_DIVIDE_CHECK(cpi->twopass.modified_error_left));
             alt_kf_bits = (int)((double)kf_boost *
                                 (alt_kf_grp_bits / (double)allocation_chunks));
             if (cpi->twopass.kf_bits > alt_kf_bits)
             {
                 cpi->twopass.kf_bits = alt_kf_bits;
             }
         }
         /* Else if it is much harder than other frames in the group make sure
          * it at least receives an allocation in keeping with its relative
          * error score
          */
         else
         {
             alt_kf_bits =
                 (int)((double)cpi->twopass.bits_left *
                       (kf_mod_err /
                        DOUBLE_DIVIDE_CHECK(cpi->twopass.modified_error_left)));
             if (alt_kf_bits > cpi->twopass.kf_bits)
             {
                 cpi->twopass.kf_bits = alt_kf_bits;
             }
         }
         cpi->twopass.kf_group_bits -= cpi->twopass.kf_bits;
         /* Add in the minimum frame allowance */
         cpi->twopass.kf_bits += cpi->min_frame_bandwidth;
         /* Peer frame bit target for this frame */
         cpi->per_frame_bandwidth = cpi->twopass.kf_bits;
         /* Convert to a per second bitrate */
         cpi->target_bandwidth = (int)(cpi->twopass.kf_bits *
                                       cpi->output_framerate);
     }
     /* Note the total error score of the kf group minus the key frame itself */
     cpi->twopass.kf_group_error_left = (int)(kf_group_err - kf_mod_err);
     /* Adjust the count of total modified error left. The count of bits left
      * is adjusted elsewhere based on real coded frame sizes
      */
     cpi->twopass.modified_error_left -= kf_group_err;
     if (cpi->oxcf.allow_spatial_resampling)
     {
         int resample_trigger = 0;
         int last_kf_resampled = 0;
         int kf_q;
         int scale_val = 0;
         int hr, hs, vr, vs;
         int new_width = cpi->oxcf.Width;
         int new_height = cpi->oxcf.Height;
         int projected_buffer_level = (int)cpi->buffer_level;
         int tmp_q;
         double projected_bits_perframe;
         double group_iiratio = (kf_group_intra_err - first_frame.intra_error) / (kf_group_coded_err - first_frame.coded_error);
         double err_per_frame = kf_group_err / cpi->twopass.frames_to_key;
         double bits_per_frame;
         double av_bits_per_frame;
         double effective_size_ratio;
         if ((cpi->common.Width != cpi->oxcf.Width) || (cpi->common.Height != cpi->oxcf.Height))
             last_kf_resampled = 1;
         /* Set back to unscaled by defaults */
         cpi->common.horiz_scale = NORMAL;
         cpi->common.vert_scale = NORMAL;
         /* Calculate Average bits per frame. */
         av_bits_per_frame = cpi->oxcf.target_bandwidth / DOUBLE_DIVIDE_CHECK((double)cpi->framerate);
         /* CBR... Use the clip average as the target for deciding resample */
         if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
         {
             bits_per_frame = av_bits_per_frame;
         }
         /* In VBR we want to avoid downsampling in easy section unless we
          * are under extreme pressure So use the larger of target bitrate
          * for this section or average bitrate for sequence
          */
         else
         {
             /* This accounts for how hard the section is... */
             bits_per_frame = (double)
                 (cpi->twopass.kf_group_bits / cpi->twopass.frames_to_key);
             /* Dont turn to resampling in easy sections just because they
              * have been assigned a small number of bits
              */
             if (bits_per_frame < av_bits_per_frame)
                 bits_per_frame = av_bits_per_frame;
         }
         /* bits_per_frame should comply with our minimum */
         if (bits_per_frame < (cpi->oxcf.target_bandwidth * cpi->oxcf.two_pass_vbrmin_section / 100))
             bits_per_frame = (cpi->oxcf.target_bandwidth * cpi->oxcf.two_pass_vbrmin_section / 100);
         /* Work out if spatial resampling is necessary */
         kf_q = estimate_kf_group_q(cpi, err_per_frame,
                                   (int)bits_per_frame, group_iiratio);
         /* If we project a required Q higher than the maximum allowed Q then
          * make a guess at the actual size of frames in this section
          */
         projected_bits_perframe = bits_per_frame;
         tmp_q = kf_q;
         while (tmp_q > cpi->worst_quality)
         {
             projected_bits_perframe *= 1.04;
             tmp_q--;
         }
         /* Guess at buffer level at the end of the section */
         projected_buffer_level = (int)
                     (cpi->buffer_level - (int)
                     ((projected_bits_perframe - av_bits_per_frame) *
                     cpi->twopass.frames_to_key));
         if (0)
         {
             FILE *f = fopen("Subsamle.stt", "a");
             fprintf(f, " %8d %8d %8d %8d %12.0f %8d %8d %8d\n",  cpi->common.current_video_frame, kf_q, cpi->common.horiz_scale, cpi->common.vert_scale,  kf_group_err / cpi->twopass.frames_to_key, (int)(cpi->twopass.kf_group_bits / cpi->twopass.frames_to_key), new_height, new_width);
             fclose(f);
         }
         /* The trigger for spatial resampling depends on the various
          * parameters such as whether we are streaming (CBR) or VBR.
          */
         if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
         {
             /* Trigger resample if we are projected to fall below down
              * sample level or resampled last time and are projected to
              * remain below the up sample level
              */
             if ((projected_buffer_level < (cpi->oxcf.resample_down_water_mark * cpi->oxcf.optimal_buffer_level / 100)) ||
                 (last_kf_resampled && (projected_buffer_level < (cpi->oxcf.resample_up_water_mark * cpi->oxcf.optimal_buffer_level / 100))))
                 resample_trigger = 1;
             else
                 resample_trigger = 0;
         }
         else
         {
             int64_t clip_bits = (int64_t)(cpi->twopass.total_stats.count * cpi->oxcf.target_bandwidth / DOUBLE_DIVIDE_CHECK((double)cpi->framerate));
             int64_t over_spend = cpi->oxcf.starting_buffer_level - cpi->buffer_level;
             /* If triggered last time the threshold for triggering again is
              * reduced:
              *
              * Projected Q higher than allowed and Overspend > 5% of total
              * bits
              */
             if ((last_kf_resampled && (kf_q > cpi->worst_quality)) ||
                 ((kf_q > cpi->worst_quality) &&
                  (over_spend > clip_bits / 20)))
                 resample_trigger = 1;
             else
                 resample_trigger = 0;
         }
         if (resample_trigger)
         {
             while ((kf_q >= cpi->worst_quality) && (scale_val < 6))
             {
                 scale_val ++;
                 cpi->common.vert_scale   = vscale_lookup[scale_val];
                 cpi->common.horiz_scale  = hscale_lookup[scale_val];
                 Scale2Ratio(cpi->common.horiz_scale, &hr, &hs);
                 Scale2Ratio(cpi->common.vert_scale, &vr, &vs);
                 new_width = ((hs - 1) + (cpi->oxcf.Width * hr)) / hs;
                 new_height = ((vs - 1) + (cpi->oxcf.Height * vr)) / vs;
                 /* Reducing the area to 1/4 does not reduce the complexity
                  * (err_per_frame) to 1/4... effective_sizeratio attempts
                  * to provide a crude correction for this
                  */
                 effective_size_ratio = (double)(new_width * new_height) / (double)(cpi->oxcf.Width * cpi->oxcf.Height);
                 effective_size_ratio = (1.0 + (3.0 * effective_size_ratio)) / 4.0;
                 /* Now try again and see what Q we get with the smaller
                  * image size
                  */
                 kf_q = estimate_kf_group_q(cpi,
                                           err_per_frame * effective_size_ratio,
                                           (int)bits_per_frame, group_iiratio);
                 if (0)
                 {
                     FILE *f = fopen("Subsamle.stt", "a");
                     fprintf(f, "******** %8d %8d %8d %12.0f %8d %8d %8d\n",  kf_q, cpi->common.horiz_scale, cpi->common.vert_scale,  kf_group_err / cpi->twopass.frames_to_key, (int)(cpi->twopass.kf_group_bits / cpi->twopass.frames_to_key), new_height, new_width);
                     fclose(f);
                 }
             }
         }
         if ((cpi->common.Width != new_width) || (cpi->common.Height != new_height))
         {
             cpi->common.Width = new_width;
             cpi->common.Height = new_height;
             vp8_alloc_compressor_data(cpi);
         }
     }
 }

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media/libvpx/vp8/encoder/firstpass.c@b8a032363ba2 (annotated)

media/libvpx/vp8/encoder/firstpass.c