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vpx/vp8/encoder/ratectrl.c
Ronald S. Bultje f64725a009 Improved coding using 8x8 transform 
In summary, this commit encompasses a series of changes in attempt to
improve the 8x8 transform based coding to help overall compression
quality, please refer to the detailed commit history below for what
are the rationale underly the series of changes:

a. A frame level flag to indicate if 8x8 transform is used at all.
b. 8x8 transform is not used for key frames and small image size.
c. On inter coded frame, macroblocks using modes B_PRED, SPLIT_MV
and I8X8_PRED are forced to using 4x4 transform based coding, the
rest uses 8x8 transform based coding.
d. Encoder and decoder has the same assumption on the relationship
between prediction modes and transform size, therefore no signaling
is encoded in bitstream.
e. Mode decision process now calculate the rate and distortion scores
using their respective transforms.

Overall test results:
1. HD set
http://www.corp.google.com/~yaowu/no_crawl/t8x8/HD_t8x8_20120206.html
(avg psnr: 3.09% glb psnr: 3.22%, ssim: 3.90%)
2. Cif set:
http://www.corp.google.com/~yaowu/no_crawl/t8x8/cif_t8x8_20120206.html
(avg psnr: -0.03%, glb psnr: -0.02%, ssim: -0.04%)
It should be noted here, as 8x8 transform coding itself is disabled
for cif size clips, the 0.03% loss is purely from the 1 bit/frame
flag overhead on if 8x8 transform is used or not for the frame.

---patch history for future reference---
Patch 1:
this commit tries to select transform size based on macroblock
prediction mode. If the size of a prediction mode is 16x16, then
the macroblock is forced to use 8x8 transform. If the prediction
mode is B_PRED, SPLITMV or I8X8_PRED, then the macroblock is forced
to use 4x4 transform. Tests on the following HD clips showed mixed
results: (all hd clips only used first 100 frames in the test)

http://www.corp.google.com/~yaowu/no_crawl/t8x8/hdmodebased8x8.html
http://www.corp.google.com/~yaowu/no_crawl/t8x8/hdmodebased8x8_log.html

while the results are mixed and overall negative, it is interesting to
see 8x8 helped a few of the clips.

Patch 2:
this patch tries to hard-wire selection of transform size based on
prediction modes without using segmentation to signal the transform size.
encoder and decoder both takes the same assumption that all macroblocks
use 8x8 transform except when prediciton mode is B_PRED, I8X8_PRED or
SPLITMV. Test results are as follows:

http://www.corp.google.com/~yaowu/no_crawl/t8x8/cifmodebase8x8_0125.html
http://www.corp.google.com/~yaowu/no_crawl/t8x8/hdmodebased8x8_0125log.html

Interestingly, by removing the overhead or coding the segmentation, the
results on this limited HD set have turn positive on average.

Patch 3:
this patch disabled the usage of 8x8 transform on key frames, and kept the
logic from patch 2 for inter frames only. test results on HD set turned
decidedly positive with 8x8 transform enabled on inter frame with 16x16
prediction modes: (avg psnr: .81% glb psnr: .82 ssim: .55%)

http://www.corp.google.com/~yaowu/no_crawl/t8x8/hdintermode8x8_0125.html
results on cif set still negative overall

Patch 4:
continued from last patch, but now in mode decision process, the rate and
distortion estimates are computed based on 8x8 transform results for MBs
with modes associated with 8x8 transform. This patch also fixed a problem
related to segment based eob coding when 8x8 transform is used. The patch
significantly improved the results on HD clips:

http://www.corp.google.com/~yaowu/no_crawl/t8x8/hd8x8RDintermode.html
(avg psnr: 2.70% glb psnr: 2.76% ssim: 3.34%)
results on cif also improved, though they are still negative compared to
baseline that uses 4x4 transform only:
http://www.corp.google.com/~yaowu/no_crawl/t8x8/cif8x8RDintermode.html
(avg psnr: -.78% glb psnr: -.86% ssim: -.19%)

Patch 5:
This patch does 3 things:
a. a bunch of decoder bug fixes, encodings and decodings were verified
to have matched recon buffer on a number of encodes on cif size mobile and
hd version of _pedestrian.
b. the patch further improved the rate distortion calculation of MBS that
use 8x8 transform. This provided some further gain on compression.
c. the patch also got the experimental work SEG_LVL_EOB to work with 8x8
transformed macroblock, test results indicates it improves the cif set
but hurt the HD set slightly.

Tests results on HD clips:
http://www.corp.google.com/~yaowu/no_crawl/t8x8/HD_t8x8_20120201.html
(avg psnr: 3.19% glb psnr: 3.30% ssim: 3.93%)

Test results on cif clips:
http://www.corp.google.com/~yaowu/no_crawl/t8x8/cif_t8x8_20120201.html
(avg psnr: -.47% glb psnr: -.51% ssim: +.28%)

Patch 6:
Added a frame level flag to indicate if 8x8 transform is allowed at all.
temporarily the decision is based on frame size, can be optimized later
one. This get the cif results to basically unchanged, with one bit per
frame overhead on both cif and hd clips.

Patch 8:
Rebase and Merge to head by PGW.
Fixed some suspect 4s that look like hey should be 64s in regard
to segmented EOB. Perhaps #defines would be bette.
Bulit and tested without T8x8 enabled and produces unchanged
output.

Patch 9:
Corrected misalligned code/decode of "txfm_mode" bit.
Limited testing for correct encode and decode with
T8x8 configured on derf clips.

Change-Id: I156e1405d25f81579d579dff8ab9af53944ec49c
2012-02-10 14:23:27 +00:00

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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 "vp8/common/common.h"
#include "ratectrl.h"
#include "vp8/common/entropymode.h"
#include "vpx_mem/vpx_mem.h"
#include "vp8/common/systemdependent.h"
#include "encodemv.h"
#define MIN_BPB_FACTOR 0.005
#define MAX_BPB_FACTOR 50
extern const MB_PREDICTION_MODE vp8_mode_order[MAX_MODES];
extern const MV_REFERENCE_FRAME vp8_ref_frame_order[MAX_MODES];
#ifdef MODE_STATS
extern int y_modes[VP8_YMODES];
extern int uv_modes[VP8_UV_MODES];
extern int b_modes[B_MODE_COUNT];
extern int inter_y_modes[MB_MODE_COUNT];
extern int inter_uv_modes[VP8_UV_MODES];
extern int inter_b_modes[B_MODE_COUNT];
#endif
// Bits Per MB at different Q (Multiplied by 512)
#define BPER_MB_NORMBITS 9
// % adjustment to target kf size based on seperation from previous frame
static const int kf_boost_seperation_adjustment[16] =
{
30, 40, 50, 55, 60, 65, 70, 75,
80, 85, 90, 95, 100, 100, 100, 100,
};
static const int gf_adjust_table[101] =
{
100,
115, 130, 145, 160, 175, 190, 200, 210, 220, 230,
240, 260, 270, 280, 290, 300, 310, 320, 330, 340,
350, 360, 370, 380, 390, 400, 400, 400, 400, 400,
400, 400, 400, 400, 400, 400, 400, 400, 400, 400,
400, 400, 400, 400, 400, 400, 400, 400, 400, 400,
400, 400, 400, 400, 400, 400, 400, 400, 400, 400,
400, 400, 400, 400, 400, 400, 400, 400, 400, 400,
400, 400, 400, 400, 400, 400, 400, 400, 400, 400,
400, 400, 400, 400, 400, 400, 400, 400, 400, 400,
400, 400, 400, 400, 400, 400, 400, 400, 400, 400,
};
static const int gf_intra_usage_adjustment[20] =
{
125, 120, 115, 110, 105, 100, 95, 85, 80, 75,
70, 65, 60, 55, 50, 50, 50, 50, 50, 50,
};
static const int gf_interval_table[101] =
{
7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
};
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 vp8_convert_qindex_to_q( int qindex )
{
// Convert the index to a real Q value (scaled down to match old Q values)
return (double)vp8_ac_yquant( qindex, 0 ) / 4.0;
}
int vp8_gfboost_qadjust( int qindex )
{
int retval;
double q;
q = vp8_convert_qindex_to_q(qindex);
retval = (int)( ( 0.00000828 * q * q * q ) +
( -0.0055 * q * q ) +
( 1.32 * q ) + 79.3 );
return retval;
}
int kfboost_qadjust( int qindex )
{
int retval;
double q;
q = vp8_convert_qindex_to_q(qindex);
retval = (int)( ( 0.00000973 * q * q * q ) +
( -0.00613 * q * q ) +
( 1.316 * q ) + 121.2 );
return retval;
}
int vp8_bits_per_mb( FRAME_TYPE frame_type, int qindex )
{
if ( frame_type == KEY_FRAME )
return (int)(4500000 / vp8_convert_qindex_to_q(qindex));
else
return (int)(2850000 / vp8_convert_qindex_to_q(qindex));
}
void vp8_save_coding_context(VP8_COMP *cpi)
{
CODING_CONTEXT *const cc = & cpi->coding_context;
// Stores a snapshot of key state variables which can subsequently be
// restored with a call to vp8_restore_coding_context. These functions are
// intended for use in a re-code loop in vp8_compress_frame where the
// quantizer value is adjusted between loop iterations.
cc->frames_since_key = cpi->frames_since_key;
cc->filter_level = cpi->common.filter_level;
cc->frames_till_gf_update_due = cpi->frames_till_gf_update_due;
cc->frames_since_golden = cpi->common.frames_since_golden;
vp8_copy(cc->mvc, cpi->common.fc.mvc);
vp8_copy(cc->mvcosts, cpi->mb.mvcosts);
vp8_copy(cc->kf_ymode_prob, cpi->common.kf_ymode_prob);
vp8_copy(cc->ymode_prob, cpi->common.fc.ymode_prob);
vp8_copy(cc->kf_uv_mode_prob, cpi->common.kf_uv_mode_prob);
vp8_copy(cc->uv_mode_prob, cpi->common.fc.uv_mode_prob);
vp8_copy(cc->ymode_count, cpi->ymode_count);
vp8_copy(cc->uv_mode_count, cpi->uv_mode_count);
// Stats
#ifdef MODE_STATS
vp8_copy(cc->y_modes, y_modes);
vp8_copy(cc->uv_modes, uv_modes);
vp8_copy(cc->b_modes, b_modes);
vp8_copy(cc->inter_y_modes, inter_y_modes);
vp8_copy(cc->inter_uv_modes, inter_uv_modes);
vp8_copy(cc->inter_b_modes, inter_b_modes);
#endif
cc->this_frame_percent_intra = cpi->this_frame_percent_intra;
}
void vp8_restore_coding_context(VP8_COMP *cpi)
{
CODING_CONTEXT *const cc = & cpi->coding_context;
// Restore key state variables to the snapshot state stored in the
// previous call to vp8_save_coding_context.
cpi->frames_since_key = cc->frames_since_key;
cpi->common.filter_level = cc->filter_level;
cpi->frames_till_gf_update_due = cc->frames_till_gf_update_due;
cpi->common.frames_since_golden = cc->frames_since_golden;
vp8_copy(cpi->common.fc.mvc, cc->mvc);
vp8_copy(cpi->mb.mvcosts, cc->mvcosts);
vp8_copy(cpi->common.kf_ymode_prob, cc->kf_ymode_prob);
vp8_copy(cpi->common.fc.ymode_prob, cc->ymode_prob);
vp8_copy(cpi->common.kf_uv_mode_prob, cc->kf_uv_mode_prob);
vp8_copy(cpi->common.fc.uv_mode_prob, cc->uv_mode_prob);
vp8_copy(cpi->ymode_count, cc->ymode_count);
vp8_copy(cpi->uv_mode_count, cc->uv_mode_count);
// Stats
#ifdef MODE_STATS
vp8_copy(y_modes, cc->y_modes);
vp8_copy(uv_modes, cc->uv_modes);
vp8_copy(b_modes, cc->b_modes);
vp8_copy(inter_y_modes, cc->inter_y_modes);
vp8_copy(inter_uv_modes, cc->inter_uv_modes);
vp8_copy(inter_b_modes, cc->inter_b_modes);
#endif
cpi->this_frame_percent_intra = cc->this_frame_percent_intra;
}
void vp8_setup_key_frame(VP8_COMP *cpi)
{
// Setup for Key frame:
vp8_default_coef_probs(& cpi->common);
vp8_kf_default_bmode_probs(cpi->common.kf_bmode_prob);
vpx_memcpy(cpi->common.fc.mvc, vp8_default_mv_context, sizeof(vp8_default_mv_context));
{
int flag[2] = {1, 1};
vp8_build_component_cost_table(cpi->mb.mvcost, (const MV_CONTEXT *) cpi->common.fc.mvc, flag);
}
vpx_memset(cpi->common.fc.pre_mvc, 0, sizeof(cpi->common.fc.pre_mvc)); //initialize pre_mvc to all zero.
#if CONFIG_T8X8
cpi->common.txfm_mode = ONLY_4X4;
#endif
//cpi->common.filter_level = 0; // Reset every key frame.
cpi->common.filter_level = cpi->common.base_qindex * 3 / 8 ;
// Provisional interval before next GF
if (cpi->auto_gold)
//cpi->frames_till_gf_update_due = DEFAULT_GF_INTERVAL;
cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
else
cpi->frames_till_gf_update_due = cpi->goldfreq;
cpi->common.refresh_golden_frame = TRUE;
cpi->common.refresh_alt_ref_frame = TRUE;
vpx_memcpy(&cpi->common.lfc, &cpi->common.fc, sizeof(cpi->common.fc));
vpx_memcpy(&cpi->common.lfc_a, &cpi->common.fc, sizeof(cpi->common.fc));
vp8_init_mode_contexts(&cpi->common);
vpx_memcpy( cpi->common.vp8_mode_contexts,
cpi->common.mode_context,
sizeof(cpi->common.mode_context));
vpx_memcpy( cpi->common.vp8_mode_contexts,
default_vp8_mode_contexts,
sizeof(default_vp8_mode_contexts));
}
void vp8_setup_inter_frame(VP8_COMP *cpi)
{
#if CONFIG_T8X8
if(cpi->common.Width * cpi->common.Height > 640*360)
cpi->common.txfm_mode = ALLOW_8X8;
else
cpi->common.txfm_mode = ONLY_4X4;
#endif
if(cpi->common.refresh_alt_ref_frame)
{
vpx_memcpy( &cpi->common.fc,
&cpi->common.lfc_a,
sizeof(cpi->common.fc));
vpx_memcpy( cpi->common.vp8_mode_contexts,
cpi->common.mode_context_a,
sizeof(cpi->common.vp8_mode_contexts));
}
else
{
vpx_memcpy( &cpi->common.fc,
&cpi->common.lfc,
sizeof(cpi->common.fc));
vpx_memcpy( cpi->common.vp8_mode_contexts,
cpi->common.mode_context,
sizeof(cpi->common.vp8_mode_contexts));
}
}
static int estimate_bits_at_q(int frame_kind, int Q, int MBs,
double correction_factor)
{
int Bpm = (int)(.5 + correction_factor * vp8_bits_per_mb(frame_kind, Q));
/* 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.
*/
if (MBs > (1 << 11))
return (Bpm >> BPER_MB_NORMBITS) * MBs;
else
return (Bpm * MBs) >> BPER_MB_NORMBITS;
}
static void calc_iframe_target_size(VP8_COMP *cpi)
{
// boost defaults to half second
int kf_boost;
int target;
// Clear down mmx registers to allow floating point in what follows
vp8_clear_system_state(); //__asm emms;
if (cpi->oxcf.fixed_q >= 0)
{
int Q = cpi->oxcf.key_q;
target = estimate_bits_at_q(INTRA_FRAME, Q, cpi->common.MBs,
cpi->key_frame_rate_correction_factor);
}
else if (cpi->pass == 2)
{
// New Two pass RC
target = cpi->per_frame_bandwidth;
}
// First Frame is a special case
else if (cpi->common.current_video_frame == 0)
{
/* 1 Pass there is no information on which to base size so use
* bandwidth per second * fraction of the initial buffer
* level
*/
target = cpi->oxcf.starting_buffer_level / 2;
if(target > cpi->oxcf.target_bandwidth * 3 / 2)
target = cpi->oxcf.target_bandwidth * 3 / 2;
}
else
{
// if this keyframe was forced, use a more recent Q estimate
int Q = (cpi->common.frame_flags & FRAMEFLAGS_KEY)
? cpi->avg_frame_qindex : cpi->ni_av_qi;
// Boost depends somewhat on frame rate
kf_boost = (int)(2 * cpi->output_frame_rate - 16);
// adjustment up based on q
kf_boost = kf_boost * kfboost_qadjust(Q) / 100;
// frame separation adjustment ( down)
if (cpi->frames_since_key < cpi->output_frame_rate / 2)
kf_boost = (int)(kf_boost
* cpi->frames_since_key / (cpi->output_frame_rate / 2));
if (kf_boost < 16)
kf_boost = 16;
target = ((16 + kf_boost) * cpi->per_frame_bandwidth) >> 4;
}
if (cpi->oxcf.rc_max_intra_bitrate_pct)
{
unsigned 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;
// TODO: if we separate rate targeting from Q targetting, move this.
// Reset the active worst quality to the baseline value for key frames.
if (cpi->pass != 2)
cpi->active_worst_quality = cpi->worst_quality;
}
// Do the best we can to define the parameteres for the next GF based on what information we have available.
static void calc_gf_params(VP8_COMP *cpi)
{
int Q = (cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q;
int Boost = 0;
int gf_frame_useage = 0; // Golden frame useage since last GF
int tot_mbs = cpi->recent_ref_frame_usage[INTRA_FRAME] +
cpi->recent_ref_frame_usage[LAST_FRAME] +
cpi->recent_ref_frame_usage[GOLDEN_FRAME] +
cpi->recent_ref_frame_usage[ALTREF_FRAME];
int pct_gf_active = (100 * cpi->gf_active_count) / (cpi->common.mb_rows * cpi->common.mb_cols);
// Reset the last boost indicator
//cpi->last_boost = 100;
if (tot_mbs)
gf_frame_useage = (cpi->recent_ref_frame_usage[GOLDEN_FRAME] + cpi->recent_ref_frame_usage[ALTREF_FRAME]) * 100 / tot_mbs;
if (pct_gf_active > gf_frame_useage)
gf_frame_useage = pct_gf_active;
// Not two pass
if (cpi->pass != 2)
{
// Single Pass lagged mode: TBD
if (FALSE)
{
}
// Single Pass compression: Has to use current and historical data
else
{
#if 0
// Experimental code
int index = cpi->one_pass_frame_index;
int frames_to_scan = (cpi->max_gf_interval <= MAX_LAG_BUFFERS) ? cpi->max_gf_interval : MAX_LAG_BUFFERS;
/*
// *************** Experimental code - incomplete
double decay_val = 1.0;
double IIAccumulator = 0.0;
double last_iiaccumulator = 0.0;
double IIRatio;
cpi->one_pass_frame_index = cpi->common.current_video_frame%MAX_LAG_BUFFERS;
for ( i = 0; i < (frames_to_scan - 1); i++ )
{
if ( index < 0 )
index = MAX_LAG_BUFFERS;
index --;
if ( cpi->one_pass_frame_stats[index].frame_coded_error > 0.0 )
{
IIRatio = cpi->one_pass_frame_stats[index].frame_intra_error / cpi->one_pass_frame_stats[index].frame_coded_error;
if ( IIRatio > 30.0 )
IIRatio = 30.0;
}
else
IIRatio = 30.0;
IIAccumulator += IIRatio * decay_val;
decay_val = decay_val * cpi->one_pass_frame_stats[index].frame_pcnt_inter;
if ( (i > MIN_GF_INTERVAL) &&
((IIAccumulator - last_iiaccumulator) < 2.0) )
{
break;
}
last_iiaccumulator = IIAccumulator;
}
Boost = IIAccumulator*100.0/16.0;
cpi->baseline_gf_interval = i;
*/
#else
/*************************************************************/
// OLD code
// Adjust boost based upon ambient Q
Boost = vp8_gfboost_qadjust(Q);
// Adjust based upon most recently measure intra useage
Boost = Boost * gf_intra_usage_adjustment[(cpi->this_frame_percent_intra < 15) ? cpi->this_frame_percent_intra : 14] / 100;
// Adjust gf boost based upon GF usage since last GF
Boost = Boost * gf_adjust_table[gf_frame_useage] / 100;
#endif
}
// golden frame boost without recode loop often goes awry. be safe by keeping numbers down.
if (!cpi->sf.recode_loop)
{
if (cpi->compressor_speed == 2)
Boost = Boost / 2;
}
// Apply an upper limit based on Q for 1 pass encodes
// TODO.
// This is a temporay measure oas one pass not really supported yet in
// the experimental branch
if (Boost > 600 && (cpi->pass == 0))
Boost = 600;
// Apply lower limits to boost.
else if (Boost < 110)
Boost = 110;
// Note the boost used
cpi->last_boost = Boost;
}
// Estimate next interval
// This is updated once the real frame size/boost is known.
if (cpi->oxcf.fixed_q == -1)
{
if (cpi->pass == 2) // 2 Pass
{
cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
}
else // 1 Pass
{
cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
if (cpi->last_boost > 750)
cpi->frames_till_gf_update_due++;
if (cpi->last_boost > 1000)
cpi->frames_till_gf_update_due++;
if (cpi->last_boost > 1250)
cpi->frames_till_gf_update_due++;
if (cpi->last_boost >= 1500)
cpi->frames_till_gf_update_due ++;
if (gf_interval_table[gf_frame_useage] > cpi->frames_till_gf_update_due)
cpi->frames_till_gf_update_due = gf_interval_table[gf_frame_useage];
if (cpi->frames_till_gf_update_due > cpi->max_gf_interval)
cpi->frames_till_gf_update_due = cpi->max_gf_interval;
}
}
else
cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
// ARF on or off
if (cpi->pass != 2)
{
// For now Alt ref is not allowed except in 2 pass modes.
cpi->source_alt_ref_pending = FALSE;
/*if ( cpi->oxcf.fixed_q == -1)
{
if ( cpi->oxcf.play_alternate && (cpi->last_boost > (100 + (AF_THRESH*cpi->frames_till_gf_update_due)) ) )
cpi->source_alt_ref_pending = TRUE;
else
cpi->source_alt_ref_pending = FALSE;
}*/
}
}
static void calc_pframe_target_size(VP8_COMP *cpi)
{
int min_frame_target;
int Adjustment;
min_frame_target = 0;
if (cpi->pass == 2)
{
min_frame_target = cpi->min_frame_bandwidth;
if (min_frame_target < (cpi->av_per_frame_bandwidth >> 5))
min_frame_target = cpi->av_per_frame_bandwidth >> 5;
}
else if (min_frame_target < cpi->per_frame_bandwidth / 4)
min_frame_target = cpi->per_frame_bandwidth / 4;
// Special alt reference frame case
if (cpi->common.refresh_alt_ref_frame)
{
if (cpi->pass == 2)
{
cpi->per_frame_bandwidth = cpi->twopass.gf_bits; // Per frame bit target for the alt ref frame
cpi->this_frame_target = cpi->per_frame_bandwidth;
}
/* One Pass ??? TBD */
/*else
{
int frames_in_section;
int allocation_chunks;
int Q = (cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q;
int alt_boost;
int max_arf_rate;
alt_boost = (cpi->gfu_boost * 3 * vp8_gfboost_qadjust(Q)) / (2 * 100);
alt_boost += (cpi->frames_till_gf_update_due * 50);
// If alt ref is not currently active then we have a pottential double hit with GF and ARF so reduce the boost a bit.
// A similar thing is done on GFs that preceed a arf update.
if ( !cpi->source_alt_ref_active )
alt_boost = alt_boost * 3 / 4;
frames_in_section = cpi->frames_till_gf_update_due+1; // Standard frames + GF
allocation_chunks = (frames_in_section * 100) + alt_boost;
// Normalize Altboost and allocations chunck down to prevent overflow
while ( alt_boost > 1000 )
{
alt_boost /= 2;
allocation_chunks /= 2;
}
else
{
int bits_in_section;
if ( cpi->kf_overspend_bits > 0 )
{
Adjustment = (cpi->kf_bitrate_adjustment <= cpi->kf_overspend_bits) ? cpi->kf_bitrate_adjustment : cpi->kf_overspend_bits;
if ( Adjustment > (cpi->per_frame_bandwidth - min_frame_target) )
Adjustment = (cpi->per_frame_bandwidth - min_frame_target);
cpi->kf_overspend_bits -= Adjustment;
// Calculate an inter frame bandwidth target for the next few frames designed to recover
// any extra bits spent on the key frame.
cpi->inter_frame_target = cpi->per_frame_bandwidth - Adjustment;
if ( cpi->inter_frame_target < min_frame_target )
cpi->inter_frame_target = min_frame_target;
}
else
cpi->inter_frame_target = cpi->per_frame_bandwidth;
bits_in_section = cpi->inter_frame_target * frames_in_section;
// Avoid loss of precision but avoid overflow
if ( (bits_in_section>>7) > allocation_chunks )
cpi->this_frame_target = alt_boost * (bits_in_section / allocation_chunks);
else
cpi->this_frame_target = (alt_boost * bits_in_section) / allocation_chunks;
}
}
*/
}
// Normal frames (gf,and inter)
else
{
// 2 pass
if (cpi->pass == 2)
{
cpi->this_frame_target = cpi->per_frame_bandwidth;
}
// 1 pass
else
{
// Make rate adjustment to recover bits spent in key frame
// Test to see if the key frame inter data rate correction should still be in force
if (cpi->kf_overspend_bits > 0)
{
Adjustment = (cpi->kf_bitrate_adjustment <= cpi->kf_overspend_bits) ? cpi->kf_bitrate_adjustment : cpi->kf_overspend_bits;
if (Adjustment > (cpi->per_frame_bandwidth - min_frame_target))
Adjustment = (cpi->per_frame_bandwidth - min_frame_target);
cpi->kf_overspend_bits -= Adjustment;
// Calculate an inter frame bandwidth target for the next few frames designed to recover
// any extra bits spent on the key frame.
cpi->this_frame_target = cpi->per_frame_bandwidth - Adjustment;
if (cpi->this_frame_target < min_frame_target)
cpi->this_frame_target = min_frame_target;
}
else
cpi->this_frame_target = cpi->per_frame_bandwidth;
// If appropriate make an adjustment to recover bits spent on a recent GF
if ((cpi->gf_overspend_bits > 0) && (cpi->this_frame_target > min_frame_target))
{
int Adjustment = (cpi->non_gf_bitrate_adjustment <= cpi->gf_overspend_bits) ? cpi->non_gf_bitrate_adjustment : cpi->gf_overspend_bits;
if (Adjustment > (cpi->this_frame_target - min_frame_target))
Adjustment = (cpi->this_frame_target - min_frame_target);
cpi->gf_overspend_bits -= Adjustment;
cpi->this_frame_target -= Adjustment;
}
// Apply small + and - boosts for non gf frames
if ((cpi->last_boost > 150) && (cpi->frames_till_gf_update_due > 0) &&
(cpi->current_gf_interval >= (MIN_GF_INTERVAL << 1)))
{
// % Adjustment limited to the range 1% to 10%
Adjustment = (cpi->last_boost - 100) >> 5;
if (Adjustment < 1)
Adjustment = 1;
else if (Adjustment > 10)
Adjustment = 10;
// Convert to bits
Adjustment = (cpi->this_frame_target * Adjustment) / 100;
if (Adjustment > (cpi->this_frame_target - min_frame_target))
Adjustment = (cpi->this_frame_target - min_frame_target);
if (cpi->common.frames_since_golden == (cpi->current_gf_interval >> 1))
cpi->this_frame_target += ((cpi->current_gf_interval - 1) * Adjustment);
else
cpi->this_frame_target -= Adjustment;
}
}
}
// Sanity check that the total sum of adjustments is not above the maximum allowed
// That is that having allowed for KF and GF penalties we have not pushed the
// current interframe target to 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->common.refresh_alt_ref_frame)
// Note the baseline target data rate for this inter frame.
cpi->inter_frame_target = cpi->this_frame_target;
// One Pass specific code
if (cpi->pass == 0)
{
// Adapt target frame size with respect to any buffering constraints:
if (cpi->buffered_mode)
{
int one_percent_bits = 1 + cpi->oxcf.optimal_buffer_level / 100;
if ((cpi->buffer_level < cpi->oxcf.optimal_buffer_level) ||
(cpi->bits_off_target < cpi->oxcf.optimal_buffer_level))
{
int percent_low = 0;
// Decide whether or not we need to adjust the frame data rate target.
//
// If we are are below the optimal buffer fullness level and adherence
// to buffering contraints is important to the end useage then adjust
// the per frame target.
if ((cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) &&
(cpi->buffer_level < cpi->oxcf.optimal_buffer_level))
{
percent_low =
(cpi->oxcf.optimal_buffer_level - cpi->buffer_level) /
one_percent_bits;
}
// Are we overshooting the long term clip data rate...
else if (cpi->bits_off_target < 0)
{
// Adjust per frame data target downwards to compensate.
percent_low = (int)(100 * -cpi->bits_off_target /
(cpi->total_byte_count * 8));
}
if (percent_low > cpi->oxcf.under_shoot_pct)
percent_low = cpi->oxcf.under_shoot_pct;
else if (percent_low < 0)
percent_low = 0;
// lower the target bandwidth for this frame.
cpi->this_frame_target -= (cpi->this_frame_target * percent_low)
/ 200;
// Are we using allowing control of active_worst_allowed_q
// according to buffer level.
if (cpi->auto_worst_q)
{
int critical_buffer_level;
// For streaming applications the most important factor is
// cpi->buffer_level as this takes into account the
// specified short term buffering constraints. However,
// hitting the long term clip data rate target is also
// important.
if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
{
// Take the smaller of cpi->buffer_level and
// cpi->bits_off_target
critical_buffer_level =
(cpi->buffer_level < cpi->bits_off_target)
? cpi->buffer_level : cpi->bits_off_target;
}
// For local file playback short term buffering contraints
// are less of an issue
else
{
// Consider only how we are doing for the clip as a
// whole
critical_buffer_level = cpi->bits_off_target;
}
// Set the active worst quality based upon the selected
// buffer fullness number.
if (critical_buffer_level < cpi->oxcf.optimal_buffer_level)
{
if ( critical_buffer_level >
(cpi->oxcf.optimal_buffer_level >> 2) )
{
int64_t qadjustment_range =
cpi->worst_quality - cpi->ni_av_qi;
int64_t above_base =
(critical_buffer_level -
(cpi->oxcf.optimal_buffer_level >> 2));
// Step active worst quality down from
// cpi->ni_av_qi when (critical_buffer_level ==
// cpi->optimal_buffer_level) to
// cpi->worst_quality when
// (critical_buffer_level ==
// cpi->optimal_buffer_level >> 2)
cpi->active_worst_quality =
cpi->worst_quality -
((qadjustment_range * above_base) /
(cpi->oxcf.optimal_buffer_level*3>>2));
}
else
{
cpi->active_worst_quality = cpi->worst_quality;
}
}
else
{
cpi->active_worst_quality = cpi->ni_av_qi;
}
}
else
{
cpi->active_worst_quality = cpi->worst_quality;
}
}
else
{
int percent_high = 0;
if ((cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
&& (cpi->buffer_level > cpi->oxcf.optimal_buffer_level))
{
percent_high = (cpi->buffer_level
- cpi->oxcf.optimal_buffer_level)
/ one_percent_bits;
}
else if (cpi->bits_off_target > cpi->oxcf.optimal_buffer_level)
{
percent_high = (int)((100 * cpi->bits_off_target)
/ (cpi->total_byte_count * 8));
}
if (percent_high > cpi->oxcf.over_shoot_pct)
percent_high = cpi->oxcf.over_shoot_pct;
else if (percent_high < 0)
percent_high = 0;
cpi->this_frame_target += (cpi->this_frame_target *
percent_high) / 200;
// Are we allowing control of active_worst_allowed_q according to bufferl level.
if (cpi->auto_worst_q)
{
// When using the relaxed buffer model stick to the user specified value
cpi->active_worst_quality = cpi->ni_av_qi;
}
else
{
cpi->active_worst_quality = cpi->worst_quality;
}
}
// Set active_best_quality to prevent quality rising too high
cpi->active_best_quality = cpi->best_quality;
// Worst quality obviously must not be better than best quality
if (cpi->active_worst_quality <= cpi->active_best_quality)
cpi->active_worst_quality = cpi->active_best_quality + 1;
}
// Unbuffered mode (eg. video conferencing)
else
{
// Set the active worst quality
cpi->active_worst_quality = cpi->worst_quality;
}
// Special trap for constrained quality mode
// "active_worst_quality" may never drop below cq level
// for any frame type.
if ( cpi->oxcf.end_usage == USAGE_CONSTRAINED_QUALITY &&
cpi->active_worst_quality < cpi->cq_target_quality)
{
cpi->active_worst_quality = cpi->cq_target_quality;
}
}
// Test to see if we have to drop a frame
// The auto-drop frame code is only used in buffered mode.
// In unbufferd mode (eg vide conferencing) the descision to
// code or drop a frame is made outside the codec in response to real
// world comms or buffer considerations.
if (cpi->drop_frames_allowed && cpi->buffered_mode &&
(cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) &&
((cpi->common.frame_type != KEY_FRAME))) //|| !cpi->oxcf.allow_spatial_resampling) )
{
// Check for a buffer underun-crisis in which case we have to drop a frame
if ((cpi->buffer_level < 0))
{
#if 0
FILE *f = fopen("dec.stt", "a");
fprintf(f, "%10d %10d %10d %10d ***** BUFFER EMPTY\n",
(int) cpi->common.current_video_frame,
cpi->decimation_factor, cpi->common.horiz_scale,
(cpi->buffer_level * 100) / cpi->oxcf.optimal_buffer_level);
fclose(f);
#endif
//vpx_log("Decoder: Drop frame due to bandwidth: %d \n",cpi->buffer_level, cpi->av_per_frame_bandwidth);
cpi->drop_frame = TRUE;
}
#if 0
// Check for other drop frame crtieria (Note 2 pass cbr uses decimation on whole KF sections)
else if ((cpi->buffer_level < cpi->oxcf.drop_frames_water_mark * cpi->oxcf.optimal_buffer_level / 100) &&
(cpi->drop_count < cpi->max_drop_count) && (cpi->pass == 0))
{
cpi->drop_frame = TRUE;
}
#endif
if (cpi->drop_frame)
{
// Update the buffer level variable.
cpi->bits_off_target += cpi->av_per_frame_bandwidth;
// Clip the buffer level at the maximum buffer size
if (cpi->bits_off_target > cpi->oxcf.maximum_buffer_size)
cpi->bits_off_target = cpi->oxcf.maximum_buffer_size;
cpi->buffer_level = cpi->bits_off_target;
}
else
cpi->drop_count = 0;
}
// Adjust target frame size for Golden Frames:
if (cpi->oxcf.error_resilient_mode == 0 &&
(cpi->frames_till_gf_update_due == 0) && !cpi->drop_frame)
{
//int Boost = 0;
int Q = (cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q;
int gf_frame_useage = 0; // Golden frame useage since last GF
int tot_mbs = cpi->recent_ref_frame_usage[INTRA_FRAME] +
cpi->recent_ref_frame_usage[LAST_FRAME] +
cpi->recent_ref_frame_usage[GOLDEN_FRAME] +
cpi->recent_ref_frame_usage[ALTREF_FRAME];
int pct_gf_active = (100 * cpi->gf_active_count) / (cpi->common.mb_rows * cpi->common.mb_cols);
// Reset the last boost indicator
//cpi->last_boost = 100;
if (tot_mbs)
gf_frame_useage = (cpi->recent_ref_frame_usage[GOLDEN_FRAME] + cpi->recent_ref_frame_usage[ALTREF_FRAME]) * 100 / tot_mbs;
if (pct_gf_active > gf_frame_useage)
gf_frame_useage = pct_gf_active;
// Is a fixed manual GF frequency being used
if (cpi->auto_gold)
{
// For one pass throw a GF if recent frame intra useage is low or the GF useage is high
if ((cpi->pass == 0) && (cpi->this_frame_percent_intra < 15 || gf_frame_useage >= 5))
cpi->common.refresh_golden_frame = TRUE;
// Two pass GF descision
else if (cpi->pass == 2)
cpi->common.refresh_golden_frame = TRUE;
}
#if 0
// Debug stats
if (0)
{
FILE *f;
f = fopen("gf_useaget.stt", "a");
fprintf(f, " %8ld %10ld %10ld %10ld %10ld\n",
cpi->common.current_video_frame, cpi->gfu_boost, vp8_gfboost_qadjust(Q), cpi->gfu_boost, gf_frame_useage);
fclose(f);
}
#endif
if (cpi->common.refresh_golden_frame == TRUE)
{
#if 0
if (0) // p_gw
{
FILE *f;
f = fopen("GFexit.stt", "a");
fprintf(f, "%8ld GF coded\n", cpi->common.current_video_frame);
fclose(f);
}
#endif
if (cpi->auto_adjust_gold_quantizer)
{
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)
{
if (cpi->pass == 2)
{
cpi->this_frame_target = cpi->per_frame_bandwidth; // The spend on the GF is defined in the two pass code for two pass encodes
}
else
{
int Boost = cpi->last_boost;
int frames_in_section = cpi->frames_till_gf_update_due + 1;
int allocation_chunks = (frames_in_section * 100) + (Boost - 100);
int bits_in_section = cpi->inter_frame_target * frames_in_section;
// Normalize Altboost and allocations chunck down to prevent overflow
while (Boost > 1000)
{
Boost /= 2;
allocation_chunks /= 2;
}
// Avoid loss of precision but avoid overflow
if ((bits_in_section >> 7) > allocation_chunks)
cpi->this_frame_target = Boost * (bits_in_section / allocation_chunks);
else
cpi->this_frame_target = (Boost * bits_in_section) / allocation_chunks;
}
}
else
cpi->this_frame_target =
(estimate_bits_at_q(1, Q, cpi->common.MBs, 1.0)
* cpi->last_boost) / 100;
}
// If there is an active ARF at this location use the minimum
// bits on this frame even if it is a contructed arf.
// The active maximum quantizer insures that an appropriate
// number of bits will be spent if needed for contstructed ARFs.
else
{
cpi->this_frame_target = 0;
}
cpi->current_gf_interval = cpi->frames_till_gf_update_due;
}
}
}
void vp8_update_rate_correction_factors(VP8_COMP *cpi, int damp_var)
{
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
vp8_clear_system_state(); //__asm emms;
if (cpi->common.frame_type == KEY_FRAME)
{
rate_correction_factor = cpi->key_frame_rate_correction_factor;
}
else
{
if (cpi->common.refresh_alt_ref_frame || cpi->common.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 =
(int)(((.5 + rate_correction_factor *
vp8_bits_per_mb(cpi->common.frame_type, Q)) *
cpi->common.MBs) / (1 << BPER_MB_NORMBITS));
// Make some allowance for cpi->zbin_over_quant
if (cpi->zbin_over_quant > 0)
{
int Z = cpi->zbin_over_quant;
double Factor = 0.99;
double factor_adjustment = 0.01 / 256.0; //(double)ZBIN_OQ_MAX;
while (Z > 0)
{
Z --;
projected_size_based_on_q =
(int)(Factor * projected_size_based_on_q);
Factor += factor_adjustment;
if (Factor >= 0.999)
Factor = 0.999;
}
}
// Work out a size correction factor.
//if ( cpi->this_frame_target > 0 )
// correction_factor = (100 * cpi->projected_frame_size) / cpi->this_frame_target;
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)(100.5 + ((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) && (Q > cpi->active_best_quality) )
else if (correction_factor < 99)
{
// We are not already at the best allowable quality
correction_factor = (int)(100.5 - ((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->common.refresh_alt_ref_frame || cpi->common.refresh_golden_frame)
cpi->gf_rate_correction_factor = rate_correction_factor;
else
cpi->rate_correction_factor = rate_correction_factor;
}
}
int vp8_regulate_q(VP8_COMP *cpi, int target_bits_per_frame)
{
int Q = cpi->active_worst_quality;
// Reset Zbin OQ value
cpi->zbin_over_quant = 0;
if (cpi->oxcf.fixed_q >= 0)
{
Q = cpi->oxcf.fixed_q;
if (cpi->common.frame_type == KEY_FRAME)
{
Q = cpi->oxcf.key_q;
}
else if (cpi->common.refresh_alt_ref_frame)
{
Q = cpi->oxcf.alt_q;
}
else if (cpi->common.refresh_golden_frame)
{
Q = cpi->oxcf.gold_q;
}
}
else
{
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->common.refresh_alt_ref_frame || cpi->common.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)(.5 + correction_factor *
vp8_bits_per_mb(cpi->common.frame_type, i ));
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);
// If we are at MAXQ then enable Q over-run which seeks to claw back additional bits through things like
// the RD multiplier and zero bin size.
if (Q >= MAXQ)
{
int zbin_oqmax;
double Factor = 0.99;
double factor_adjustment = 0.01 / 256.0; //(double)ZBIN_OQ_MAX;
if (cpi->common.frame_type == KEY_FRAME)
zbin_oqmax = 0; //ZBIN_OQ_MAX/16
else if (cpi->common.refresh_alt_ref_frame || (cpi->common.refresh_golden_frame && !cpi->source_alt_ref_active))
zbin_oqmax = 16;
else
zbin_oqmax = ZBIN_OQ_MAX;
/*{
double Factor = (double)target_bits_per_mb/(double)bits_per_mb_at_this_q;
double Oq;
Factor = Factor/1.2683;
Oq = pow( Factor, (1.0/-0.165) );
if ( Oq > zbin_oqmax )
Oq = zbin_oqmax;
cpi->zbin_over_quant = (int)Oq;
}*/
// Each incrment in the zbin is assumed to have a fixed effect on bitrate. This is not of course true.
// The effect will be highly clip dependent and may well have sudden steps.
// The idea here is to acheive higher effective quantizers than the normal maximum by expanding the zero
// bin and hence decreasing the number of low magnitude non zero coefficients.
while (cpi->zbin_over_quant < zbin_oqmax)
{
cpi->zbin_over_quant ++;
if (cpi->zbin_over_quant > zbin_oqmax)
cpi->zbin_over_quant = zbin_oqmax;
// Adjust bits_per_mb_at_this_q estimate
bits_per_mb_at_this_q = (int)(Factor * bits_per_mb_at_this_q);
Factor += factor_adjustment;
if (Factor >= 0.999)
Factor = 0.999;
if (bits_per_mb_at_this_q <= target_bits_per_mb) // Break out if we get down to the target rate
break;
}
}
}
return Q;
}
static int estimate_keyframe_frequency(VP8_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_frame_rate * 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 vp8_adjust_key_frame_context(VP8_COMP *cpi)
{
// Clear down mmx registers to allow floating point in what follows
vp8_clear_system_state();
// Do we have any key frame overspend to recover?
// Two-pass overspend handled elsewhere.
if ((cpi->pass != 2)
&& (cpi->projected_frame_size > cpi->per_frame_bandwidth))
{
int overspend;
/* Update the count of key frame overspend to be recovered in
* subsequent frames. A portion of the KF overspend is treated as gf
* overspend (and hence recovered more quickly) as the kf is also a
* gf. Otherwise the few frames following each kf tend to get more
* bits allocated than those following other gfs.
*/
overspend = (cpi->projected_frame_size - cpi->per_frame_bandwidth);
cpi->kf_overspend_bits += overspend * 7 / 8;
cpi->gf_overspend_bits += overspend * 1 / 8;
/* Work out how much to try and recover per frame. */
cpi->kf_bitrate_adjustment = cpi->kf_overspend_bits
/ estimate_keyframe_frequency(cpi);
}
cpi->frames_since_key = 0;
cpi->key_frame_count++;
}
void vp8_compute_frame_size_bounds(VP8_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->common.refresh_alt_ref_frame || cpi->common.refresh_golden_frame)
{
*frame_over_shoot_limit = cpi->this_frame_target * 9 / 8;
*frame_under_shoot_limit = cpi->this_frame_target * 7 / 8;
}
else
{
// For CBR take buffer fullness into account
if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
{
if (cpi->buffer_level >= ((cpi->oxcf.optimal_buffer_level + cpi->oxcf.maximum_buffer_size) >> 1))
{
// Buffer is too full so relax overshoot and tighten undershoot
*frame_over_shoot_limit = cpi->this_frame_target * 12 / 8;
*frame_under_shoot_limit = cpi->this_frame_target * 6 / 8;
}
else if (cpi->buffer_level <= (cpi->oxcf.optimal_buffer_level >> 1))
{
// Buffer is too low so relax undershoot and tighten overshoot
*frame_over_shoot_limit = cpi->this_frame_target * 10 / 8;
*frame_under_shoot_limit = cpi->this_frame_target * 4 / 8;
}
else
{
*frame_over_shoot_limit = cpi->this_frame_target * 11 / 8;
*frame_under_shoot_limit = cpi->this_frame_target * 5 / 8;
}
}
// VBR and CQ mode
// Note that tighter restrictions here can help quality but hurt encode speed
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 vp8_pick_frame_size(VP8_COMP *cpi)
{
VP8_COMMON *cm = &cpi->common;
if (cm->frame_type == KEY_FRAME)
calc_iframe_target_size(cpi);
else
{
calc_pframe_target_size(cpi);
// Check if we're dropping the frame:
if (cpi->drop_frame)
{
cpi->drop_frame = FALSE;
cpi->drop_count++;
return 0;
}
}
return 1;
}
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