The Tor Browser: media/libvpx/vp9/encoder/vp9_ratectrl.c@6474c204b198 (annotated)

media/libvpx/vp9/encoder/vp9_ratectrl.c@6474c204b198 (annotated)

media/libvpx/vp9/encoder/vp9_ratectrl.c

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /*
  *  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;
 }

The Tor Browser / annotate

media/libvpx/vp9/encoder/vp9_ratectrl.c@6474c204b198 (annotated)

media/libvpx/vp9/encoder/vp9_ratectrl.c