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 /*

  *  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 <stdlib.h>

 #include <stdio.h>

 #include <string.h>

 #include <limits.h>

 #include <assert.h>

 #include <math.h>

 #include "vp9/common/vp9_alloccommon.h"

 #include "vp9/common/vp9_common.h"

 #include "vp9/encoder/vp9_ratectrl.h"

 #include "vp9/common/vp9_entropymode.h"

 #include "vpx_mem/vpx_mem.h"

 #include "vp9/common/vp9_systemdependent.h"

 #include "vp9/encoder/vp9_encodemv.h"

 #include "vp9/common/vp9_quant_common.h"

 #include "vp9/common/vp9_seg_common.h"

 #define MIN_BPB_FACTOR 0.005

 #define MAX_BPB_FACTOR 50

 // Bits Per MB at different Q (Multiplied by 512)

 #define BPER_MB_NORMBITS    9

 static const unsigned int prior_key_frame_weight[KEY_FRAME_CONTEXT] =

     { 1, 2, 3, 4, 5 };

 // These functions use formulaic calculations to make playing with the

 // quantizer tables easier. If necessary they can be replaced by lookup

 // tables if and when things settle down in the experimental bitstream

 double vp9_convert_qindex_to_q(int qindex) {

   // Convert the index to a real Q value (scaled down to match old Q values)

   return vp9_ac_quant(qindex, 0) / 4.0;

 }

 int vp9_gfboost_qadjust(int qindex) {

   const double q = vp9_convert_qindex_to_q(qindex);

   return (int)((0.00000828 * q * q * q) +

                (-0.0055 * q * q) +

                (1.32 * q) + 79.3);

 }

 static int kfboost_qadjust(int qindex) {

   const double q = vp9_convert_qindex_to_q(qindex);

   return (int)((0.00000973 * q * q * q) +

                (-0.00613 * q * q) +

                (1.316 * q) + 121.2);

 }

 int vp9_bits_per_mb(FRAME_TYPE frame_type, int qindex,

                     double correction_factor) {

   const double q = vp9_convert_qindex_to_q(qindex);

   int enumerator = frame_type == KEY_FRAME ? 3300000 : 2250000;

   // q based adjustment to baseline enumerator

   enumerator += (int)(enumerator * q) >> 12;

   return (int)(0.5 + (enumerator * correction_factor / q));

 }

 void vp9_save_coding_context(VP9_COMP *cpi) {

   CODING_CONTEXT *const cc = &cpi->coding_context;

   VP9_COMMON *cm = &cpi->common;

   // Stores a snapshot of key state variables which can subsequently be

   // restored with a call to vp9_restore_coding_context. These functions are

   // intended for use in a re-code loop in vp9_compress_frame where the

   // quantizer value is adjusted between loop iterations.

   vp9_copy(cc->nmvjointcost,  cpi->mb.nmvjointcost);

   vp9_copy(cc->nmvcosts,  cpi->mb.nmvcosts);

   vp9_copy(cc->nmvcosts_hp,  cpi->mb.nmvcosts_hp);

   vp9_copy(cc->segment_pred_probs, cm->seg.pred_probs);

   vpx_memcpy(cpi->coding_context.last_frame_seg_map_copy,

              cm->last_frame_seg_map, (cm->mi_rows * cm->mi_cols));

   vp9_copy(cc->last_ref_lf_deltas, cm->lf.last_ref_deltas);

   vp9_copy(cc->last_mode_lf_deltas, cm->lf.last_mode_deltas);

   cc->fc = cm->fc;

 }

 void vp9_restore_coding_context(VP9_COMP *cpi) {

   CODING_CONTEXT *const cc = &cpi->coding_context;

   VP9_COMMON *cm = &cpi->common;

   // Restore key state variables to the snapshot state stored in the

   // previous call to vp9_save_coding_context.

   vp9_copy(cpi->mb.nmvjointcost, cc->nmvjointcost);

   vp9_copy(cpi->mb.nmvcosts, cc->nmvcosts);

   vp9_copy(cpi->mb.nmvcosts_hp, cc->nmvcosts_hp);

   vp9_copy(cm->seg.pred_probs, cc->segment_pred_probs);

   vpx_memcpy(cm->last_frame_seg_map,

              cpi->coding_context.last_frame_seg_map_copy,

              (cm->mi_rows * cm->mi_cols));

   vp9_copy(cm->lf.last_ref_deltas, cc->last_ref_lf_deltas);

   vp9_copy(cm->lf.last_mode_deltas, cc->last_mode_lf_deltas);

   cm->fc = cc->fc;

 }

 void vp9_setup_key_frame(VP9_COMP *cpi) {

   VP9_COMMON *cm = &cpi->common;

   vp9_setup_past_independence(cm);

   // interval before next GF

   cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;

   /* All buffers are implicitly updated on key frames. */

   cpi->refresh_golden_frame = 1;

   cpi->refresh_alt_ref_frame = 1;

 }

 void vp9_setup_inter_frame(VP9_COMP *cpi) {

   VP9_COMMON *cm = &cpi->common;

   if (cm->error_resilient_mode || cm->intra_only)

     vp9_setup_past_independence(cm);

   assert(cm->frame_context_idx < NUM_FRAME_CONTEXTS);

   cm->fc = cm->frame_contexts[cm->frame_context_idx];

 }

 static int estimate_bits_at_q(int frame_kind, int q, int mbs,

                               double correction_factor) {

   const int bpm = (int)(vp9_bits_per_mb(frame_kind, q, correction_factor));

   // Attempt to retain reasonable accuracy without overflow. The cutoff is

   // chosen such that the maximum product of Bpm and MBs fits 31 bits. The

   // largest Bpm takes 20 bits.

   return (mbs > (1 << 11)) ? (bpm >> BPER_MB_NORMBITS) * mbs

                            : (bpm * mbs) >> BPER_MB_NORMBITS;

 }

 static void calc_iframe_target_size(VP9_COMP *cpi) {

   // boost defaults to half second

   int target;

   // Clear down mmx registers to allow floating point in what follows

   vp9_clear_system_state();  // __asm emms;

   // New Two pass RC

   target = cpi->per_frame_bandwidth;

   if (cpi->oxcf.rc_max_intra_bitrate_pct) {

     int max_rate = cpi->per_frame_bandwidth

                  * cpi->oxcf.rc_max_intra_bitrate_pct / 100;

     if (target > max_rate)

       target = max_rate;

   }

   cpi->this_frame_target = target;

 }

 //  Do the best we can to define the parameters for the next GF based

 //  on what information we have available.

 //

 //  In this experimental code only two pass is supported

 //  so we just use the interval determined in the two pass code.

 static void calc_gf_params(VP9_COMP *cpi) {

   // Set the gf interval

   cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;

 }

 static void calc_pframe_target_size(VP9_COMP *cpi) {

   const int min_frame_target = MAX(cpi->min_frame_bandwidth,

                                    cpi->av_per_frame_bandwidth >> 5);

   if (cpi->refresh_alt_ref_frame) {

     // Special alt reference frame case

     // Per frame bit target for the alt ref frame

     cpi->per_frame_bandwidth = cpi->twopass.gf_bits;

     cpi->this_frame_target = cpi->per_frame_bandwidth;

   } else {

     // Normal frames (gf,and inter)

     cpi->this_frame_target = cpi->per_frame_bandwidth;

   }

   // Check that the total sum of adjustments is not above the maximum allowed.

   // That is, having allowed for the KF and GF penalties, we have not pushed

   // the current inter-frame target too low. If the adjustment we apply here is

   // not capable of recovering all the extra bits we have spent in the KF or GF,

   // then the remainder will have to be recovered over a longer time span via

   // other buffer / rate control mechanisms.

   if (cpi->this_frame_target < min_frame_target)

     cpi->this_frame_target = min_frame_target;

   if (!cpi->refresh_alt_ref_frame)

     // Note the baseline target data rate for this inter frame.

     cpi->inter_frame_target = cpi->this_frame_target;

   // Adjust target frame size for Golden Frames:

   if (cpi->frames_till_gf_update_due == 0) {

     const int q = (cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME]

                                           : cpi->oxcf.fixed_q;

     cpi->refresh_golden_frame = 1;

     calc_gf_params(cpi);

     // If we are using alternate ref instead of gf then do not apply the boost

     // It will instead be applied to the altref update

     // Jims modified boost

     if (!cpi->source_alt_ref_active) {

       if (cpi->oxcf.fixed_q < 0) {

         // The spend on the GF is defined in the two pass code

         // for two pass encodes

         cpi->this_frame_target = cpi->per_frame_bandwidth;

       } else {

         cpi->this_frame_target =

           (estimate_bits_at_q(1, q, cpi->common.MBs, 1.0)

            * cpi->last_boost) / 100;

       }

     } else {

       // If there is an active ARF at this location use the minimum

       // bits on this frame even if it is a constructed arf.

       // The active maximum quantizer insures that an appropriate

       // number of bits will be spent if needed for constructed ARFs.

       cpi->this_frame_target = 0;

     }

   }

 }

 void vp9_update_rate_correction_factors(VP9_COMP *cpi, int damp_var) {

   const int q = cpi->common.base_qindex;

   int correction_factor = 100;

   double rate_correction_factor;

   double adjustment_limit;

   int projected_size_based_on_q = 0;

   // Clear down mmx registers to allow floating point in what follows

   vp9_clear_system_state();  // __asm emms;

   if (cpi->common.frame_type == KEY_FRAME) {

     rate_correction_factor = cpi->key_frame_rate_correction_factor;

   } else {

     if (cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame)

       rate_correction_factor = cpi->gf_rate_correction_factor;

     else

       rate_correction_factor = cpi->rate_correction_factor;

   }

   // Work out how big we would have expected the frame to be at this Q given

   // the current correction factor.

   // Stay in double to avoid int overflow when values are large

   projected_size_based_on_q = estimate_bits_at_q(cpi->common.frame_type, q,

                                                  cpi->common.MBs,

                                                  rate_correction_factor);

   // Work out a size correction factor.

   if (projected_size_based_on_q > 0)

     correction_factor =

         (100 * cpi->projected_frame_size) / projected_size_based_on_q;

   // More heavily damped adjustment used if we have been oscillating either side

   // of target.

   switch (damp_var) {

     case 0:

       adjustment_limit = 0.75;

       break;

     case 1:

       adjustment_limit = 0.375;

       break;

     case 2:

     default:

       adjustment_limit = 0.25;

       break;

   }

   // if ( (correction_factor > 102) && (Q < cpi->active_worst_quality) )

   if (correction_factor > 102) {

     // We are not already at the worst allowable quality

     correction_factor =

         (int)(100 + ((correction_factor - 100) * adjustment_limit));

     rate_correction_factor =

         ((rate_correction_factor * correction_factor) / 100);

     // Keep rate_correction_factor within limits

     if (rate_correction_factor > MAX_BPB_FACTOR)

       rate_correction_factor = MAX_BPB_FACTOR;

   } else if (correction_factor < 99) {

     // We are not already at the best allowable quality

     correction_factor =

         (int)(100 - ((100 - correction_factor) * adjustment_limit));

     rate_correction_factor =

         ((rate_correction_factor * correction_factor) / 100);

     // Keep rate_correction_factor within limits

     if (rate_correction_factor < MIN_BPB_FACTOR)

       rate_correction_factor = MIN_BPB_FACTOR;

   }

   if (cpi->common.frame_type == KEY_FRAME) {

     cpi->key_frame_rate_correction_factor = rate_correction_factor;

   } else {

     if (cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame)

       cpi->gf_rate_correction_factor = rate_correction_factor;

     else

       cpi->rate_correction_factor = rate_correction_factor;

   }

 }

 int vp9_regulate_q(VP9_COMP *cpi, int target_bits_per_frame) {

   int q = cpi->active_worst_quality;

   int i;

   int last_error = INT_MAX;

   int target_bits_per_mb;

   int bits_per_mb_at_this_q;

   double correction_factor;

   // Select the appropriate correction factor based upon type of frame.

   if (cpi->common.frame_type == KEY_FRAME) {

     correction_factor = cpi->key_frame_rate_correction_factor;

   } else {

     if (cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame)

       correction_factor = cpi->gf_rate_correction_factor;

     else

       correction_factor = cpi->rate_correction_factor;

   }

   // Calculate required scaling factor based on target frame size and size of

   // frame produced using previous Q.

   if (target_bits_per_frame >= (INT_MAX >> BPER_MB_NORMBITS))

     target_bits_per_mb =

         (target_bits_per_frame / cpi->common.MBs)

         << BPER_MB_NORMBITS;  // Case where we would overflow int

   else

     target_bits_per_mb =

         (target_bits_per_frame << BPER_MB_NORMBITS) / cpi->common.MBs;

   i = cpi->active_best_quality;

   do {

     bits_per_mb_at_this_q = (int)vp9_bits_per_mb(cpi->common.frame_type, i,

                                                  correction_factor);

     if (bits_per_mb_at_this_q <= target_bits_per_mb) {

       if ((target_bits_per_mb - bits_per_mb_at_this_q) <= last_error)

         q = i;

       else

         q = i - 1;

       break;

     } else {

       last_error = bits_per_mb_at_this_q - target_bits_per_mb;

     }

   } while (++i <= cpi->active_worst_quality);

   return q;

 }

 static int estimate_keyframe_frequency(VP9_COMP *cpi) {

   int i;

   // Average key frame frequency

   int av_key_frame_frequency = 0;

   /* First key frame at start of sequence is a special case. We have no

    * frequency data.

    */

   if (cpi->key_frame_count == 1) {

     /* Assume a default of 1 kf every 2 seconds, or the max kf interval,

      * whichever is smaller.

      */

     int key_freq = cpi->oxcf.key_freq > 0 ? cpi->oxcf.key_freq : 1;

     av_key_frame_frequency = (int)cpi->output_framerate * 2;

     if (cpi->oxcf.auto_key && av_key_frame_frequency > key_freq)

       av_key_frame_frequency = cpi->oxcf.key_freq;

     cpi->prior_key_frame_distance[KEY_FRAME_CONTEXT - 1]

       = av_key_frame_frequency;

   } else {

     unsigned int total_weight = 0;

     int last_kf_interval =

       (cpi->frames_since_key > 0) ? cpi->frames_since_key : 1;

     /* reset keyframe context and calculate weighted average of last

      * KEY_FRAME_CONTEXT keyframes

      */

     for (i = 0; i < KEY_FRAME_CONTEXT; i++) {

       if (i < KEY_FRAME_CONTEXT - 1)

         cpi->prior_key_frame_distance[i]

           = cpi->prior_key_frame_distance[i + 1];

       else

         cpi->prior_key_frame_distance[i] = last_kf_interval;

       av_key_frame_frequency += prior_key_frame_weight[i]

                                 * cpi->prior_key_frame_distance[i];

       total_weight += prior_key_frame_weight[i];

     }

     av_key_frame_frequency /= total_weight;

   }

   return av_key_frame_frequency;

 }

 void vp9_adjust_key_frame_context(VP9_COMP *cpi) {

   // Clear down mmx registers to allow floating point in what follows

   vp9_clear_system_state();

   cpi->frames_since_key = 0;

   cpi->key_frame_count++;

 }

 void vp9_compute_frame_size_bounds(VP9_COMP *cpi, int *frame_under_shoot_limit,

                                    int *frame_over_shoot_limit) {

   // Set-up bounds on acceptable frame size:

   if (cpi->oxcf.fixed_q >= 0) {

     // Fixed Q scenario: frame size never outranges target (there is no target!)

     *frame_under_shoot_limit = 0;

     *frame_over_shoot_limit  = INT_MAX;

   } else {

     if (cpi->common.frame_type == KEY_FRAME) {

       *frame_over_shoot_limit  = cpi->this_frame_target * 9 / 8;

       *frame_under_shoot_limit = cpi->this_frame_target * 7 / 8;

     } else {

       if (cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame) {

         *frame_over_shoot_limit  = cpi->this_frame_target * 9 / 8;

         *frame_under_shoot_limit = cpi->this_frame_target * 7 / 8;

       } else {

         // Stron overshoot limit for constrained quality

         if (cpi->oxcf.end_usage == USAGE_CONSTRAINED_QUALITY) {

           *frame_over_shoot_limit  = cpi->this_frame_target * 11 / 8;

           *frame_under_shoot_limit = cpi->this_frame_target * 2 / 8;

         } else {

           *frame_over_shoot_limit  = cpi->this_frame_target * 11 / 8;

           *frame_under_shoot_limit = cpi->this_frame_target * 5 / 8;

         }

       }

     }

     // For very small rate targets where the fractional adjustment

     // (eg * 7/8) may be tiny make sure there is at least a minimum

     // range.

     *frame_over_shoot_limit += 200;

     *frame_under_shoot_limit -= 200;

     if (*frame_under_shoot_limit < 0)

       *frame_under_shoot_limit = 0;

   }

 }

 // return of 0 means drop frame

 int vp9_pick_frame_size(VP9_COMP *cpi) {

   VP9_COMMON *cm = &cpi->common;

   if (cm->frame_type == KEY_FRAME)

     calc_iframe_target_size(cpi);

   else

     calc_pframe_target_size(cpi);

   return 1;

 }