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vpx/vp8/encoder/ratectrl.c
Yaowu Xu ade43d9125 change to allow 8x8 transform always 
This commit changed to enable the usage 8x8 transform for all frame
type, all resolution and all quantizer range. This has an overall
benefit .2% to .3% in term of compression, but more importantly,
the difficult clips benefits much more, up to 2% to 3% on clips
like football, harbour and so on.

We observed some weird humps on very high end on a couple of youtube
clips, but have determined the underly cause was the aggressive zbin
having an effect of lowering rate with lower quality, which have
an impact on slide show clips around 60DB.

The commit does not change the association between prediction mode
and transform size.

Change-Id: I33043bdce6207528ae00b4a4b26d8ff63cfea1f4
2012-04-20 09:17:59 -07:00

770 lines
24 KiB
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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;
VP8_COMMON *cm = &cpi->common;
MACROBLOCKD *xd = &cpi->mb.e_mbd;
// 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.
vp8_copy(cc->mvc, cm->fc.mvc);
vp8_copy(cc->mvcosts, cpi->mb.mvcosts);
#if CONFIG_HIGH_PRECISION_MV
vp8_copy(cc->mvc_hp, cm->fc.mvc_hp);
vp8_copy(cc->mvcosts_hp, cpi->mb.mvcosts_hp);
#endif
vp8_copy( cc->mv_ref_ct, cm->mv_ref_ct );
vp8_copy( cc->mode_context, cm->mode_context );
vp8_copy( cc->mv_ref_ct_a, cm->mv_ref_ct_a );
vp8_copy( cc->mode_context_a, cm->mode_context_a );
vp8_copy( cc->ymode_prob, cm->fc.ymode_prob );
vp8_copy( cc->uv_mode_prob, cm->fc.uv_mode_prob );
// 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
vp8_copy( cc->segment_pred_probs, cm->segment_pred_probs );
vp8_copy( cc->ref_pred_probs_update, cpi->ref_pred_probs_update );
vp8_copy( cc->ref_pred_probs, cm->ref_pred_probs );
vp8_copy( cc->prob_comppred, cm->prob_comppred );
vpx_memcpy( cpi->coding_context.last_frame_seg_map_copy,
cm->last_frame_seg_map, (cm->mb_rows * cm->mb_cols) );
vp8_copy( cc->last_ref_lf_deltas, xd->last_ref_lf_deltas );
vp8_copy( cc->last_mode_lf_deltas, xd->last_mode_lf_deltas );
vp8_copy( cc->coef_probs, cm->fc.coef_probs );
vp8_copy( cc->coef_probs_8x8, cm->fc.coef_probs_8x8 );
}
void vp8_restore_coding_context(VP8_COMP *cpi)
{
CODING_CONTEXT *const cc = & cpi->coding_context;
VP8_COMMON *cm = &cpi->common;
MACROBLOCKD *xd = &cpi->mb.e_mbd;
// Restore key state variables to the snapshot state stored in the
// previous call to vp8_save_coding_context.
vp8_copy(cm->fc.mvc, cc->mvc);
vp8_copy(cpi->mb.mvcosts, cc->mvcosts);
#if CONFIG_HIGH_PRECISION_MV
vp8_copy(cm->fc.mvc_hp, cc->mvc_hp);
vp8_copy(cpi->mb.mvcosts_hp, cc->mvcosts_hp);
#endif
vp8_copy( cm->mv_ref_ct, cc->mv_ref_ct );
vp8_copy( cm->mode_context, cc->mode_context );
vp8_copy( cm->mv_ref_ct_a, cc->mv_ref_ct_a );
vp8_copy( cm->mode_context_a, cc->mode_context_a );
vp8_copy( cm->fc.ymode_prob, cc->ymode_prob);
vp8_copy( cm->fc.uv_mode_prob, cc->uv_mode_prob);
// 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
vp8_copy( cm->segment_pred_probs, cc->segment_pred_probs );
vp8_copy( cpi->ref_pred_probs_update, cc->ref_pred_probs_update );
vp8_copy( cm->ref_pred_probs, cc->ref_pred_probs );
vp8_copy( cm->prob_comppred, cc->prob_comppred );
vpx_memcpy( cm->last_frame_seg_map,
cpi->coding_context.last_frame_seg_map_copy,
(cm->mb_rows * cm->mb_cols) );
vp8_copy( xd->last_ref_lf_deltas, cc->last_ref_lf_deltas );
vp8_copy( xd->last_mode_lf_deltas, cc->last_mode_lf_deltas );
vp8_copy( cm->fc.coef_probs, cc->coef_probs );
vp8_copy( cm->fc.coef_probs_8x8, cc->coef_probs_8x8 );
}
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);
vp8_init_mbmode_probs(& cpi->common);
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);
}
#if CONFIG_HIGH_PRECISION_MV
vpx_memcpy(cpi->common.fc.mvc_hp, vp8_default_mv_context_hp, sizeof(vp8_default_mv_context_hp));
{
int flag[2] = {1, 1};
vp8_build_component_cost_table_hp(cpi->mb.mvcost_hp, (const MV_CONTEXT_HP *) cpi->common.fc.mvc_hp, flag);
}
#endif
cpi->common.txfm_mode = ALLOW_8X8;
//cpi->common.filter_level = 0; // Reset every key frame.
cpi->common.filter_level = cpi->common.base_qindex * 3 / 8 ;
// interval before next GF
cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
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)
{
cpi->common.txfm_mode = ALLOW_8X8;
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;
// New Two pass RC
target = cpi->per_frame_bandwidth;
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;
}
// Do the best we can to define the parameteres 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(VP8_COMP *cpi)
{
// Set the gf interval
cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
}
static void calc_pframe_target_size(VP8_COMP *cpi)
{
int min_frame_target;
int Adjustment;
min_frame_target = 0;
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;
// Special alt reference frame case
if (cpi->common.refresh_alt_ref_frame)
{
// 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;
}
// Normal frames (gf,and inter)
else
{
cpi->this_frame_target = cpi->per_frame_bandwidth;
}
// 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;
// Adjust target frame size for Golden Frames:
if ( cpi->frames_till_gf_update_due == 0 )
{
//int Boost = 0;
int Q = (cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q;
cpi->common.refresh_golden_frame = TRUE;
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;
}
// 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;
int i;
int last_error = INT_MAX;
int target_bits_per_mb;
int bits_per_mb_at_this_q;
double correction_factor;
// Reset Zbin OQ value
cpi->zbin_over_quant = 0;
// 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;
// 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();
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
{
// 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);
return 1;
}
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