ref: d36cc98ee3a9bf37865c8fc83774f9982bbc6dd6
dir: /vp8/encoder/ratectrl.c/
/*
* 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/alloccommon.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"
#include "vp8/common/quant_common.h"
#define MIN_BPB_FACTOR 0.005
#define MAX_BPB_FACTOR 50
extern const MODE_DEFINITION vp8_mode_order[MAX_MODES];
#ifdef MODE_STATS
extern unsigned int y_modes[VP8_YMODES];
extern unsigned int uv_modes[VP8_UV_MODES];
extern unsigned int b_modes[B_MODE_COUNT];
extern unsigned int inter_y_modes[MB_MODE_COUNT];
extern unsigned int inter_uv_modes[VP8_UV_MODES];
extern unsigned 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) / 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;
}
static 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.
cc->nmvc = cm->fc.nmvc;
vp8_copy(cc->nmvjointcost, cpi->mb.nmvjointcost);
vp8_copy(cc->nmvcosts, cpi->mb.nmvcosts);
vp8_copy(cc->nmvcosts_hp, cpi->mb.nmvcosts_hp);
vp8_copy(cc->mv_ref_ct, cm->fc.mv_ref_ct);
vp8_copy(cc->mode_context, cm->fc.mode_context);
vp8_copy(cc->mv_ref_ct_a, cm->fc.mv_ref_ct_a);
vp8_copy(cc->mode_context_a, cm->fc.mode_context_a);
vp8_copy(cc->ymode_prob, cm->fc.ymode_prob);
vp8_copy(cc->bmode_prob, cm->fc.bmode_prob);
vp8_copy(cc->uv_mode_prob, cm->fc.uv_mode_prob);
vp8_copy(cc->i8x8_mode_prob, cm->fc.i8x8_mode_prob);
vp8_copy(cc->sub_mv_ref_prob, cm->fc.sub_mv_ref_prob);
vp8_copy(cc->mbsplit_prob, cm->fc.mbsplit_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->hybrid_coef_probs, cm->fc.hybrid_coef_probs);
vp8_copy(cc->coef_probs_8x8, cm->fc.coef_probs_8x8);
vp8_copy(cc->hybrid_coef_probs_8x8, cm->fc.hybrid_coef_probs_8x8);
vp8_copy(cc->coef_probs_16x16, cm->fc.coef_probs_16x16);
vp8_copy(cc->hybrid_coef_probs_16x16, cm->fc.hybrid_coef_probs_16x16);
vp8_copy(cc->switchable_interp_prob, cm->fc.switchable_interp_prob);
}
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.
cm->fc.nmvc = cc->nmvc;
vp8_copy(cpi->mb.nmvjointcost, cc->nmvjointcost);
vp8_copy(cpi->mb.nmvcosts, cc->nmvcosts);
vp8_copy(cpi->mb.nmvcosts_hp, cc->nmvcosts_hp);
vp8_copy(cm->fc.mv_ref_ct, cc->mv_ref_ct);
vp8_copy(cm->fc.mode_context, cc->mode_context);
vp8_copy(cm->fc.mv_ref_ct_a, cc->mv_ref_ct_a);
vp8_copy(cm->fc.mode_context_a, cc->mode_context_a);
vp8_copy(cm->fc.ymode_prob, cc->ymode_prob);
vp8_copy(cm->fc.bmode_prob, cc->bmode_prob);
vp8_copy(cm->fc.i8x8_mode_prob, cc->i8x8_mode_prob);
vp8_copy(cm->fc.uv_mode_prob, cc->uv_mode_prob);
vp8_copy(cm->fc.sub_mv_ref_prob, cc->sub_mv_ref_prob);
vp8_copy(cm->fc.mbsplit_prob, cc->mbsplit_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.hybrid_coef_probs, cc->hybrid_coef_probs);
vp8_copy(cm->fc.coef_probs_8x8, cc->coef_probs_8x8);
vp8_copy(cm->fc.hybrid_coef_probs_8x8, cc->hybrid_coef_probs_8x8);
vp8_copy(cm->fc.coef_probs_16x16, cc->coef_probs_16x16);
vp8_copy(cm->fc.hybrid_coef_probs_16x16, cc->hybrid_coef_probs_16x16);
vp8_copy(cm->fc.switchable_interp_prob, cc->switchable_interp_prob);
}
void vp8_setup_key_frame(VP8_COMP *cpi) {
VP8_COMMON *cm = &cpi->common;
// 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);
vp8_default_bmode_probs(cm->fc.bmode_prob);
vp8_init_mv_probs(& cpi->common);
// 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;
vp8_init_mode_contexts(&cpi->common);
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));
vpx_memset(cm->prev_mip, 0,
(cm->mb_cols + 1) * (cm->mb_rows + 1)* sizeof(MODE_INFO));
vpx_memset(cm->mip, 0,
(cm->mb_cols + 1) * (cm->mb_rows + 1)* sizeof(MODE_INFO));
vp9_update_mode_info_border(cm, cm->mip);
vp9_update_mode_info_in_image(cm, cm->mi);
}
void vp8_setup_inter_frame(VP8_COMP *cpi) {
if (cpi->common.refresh_alt_ref_frame) {
vpx_memcpy(&cpi->common.fc,
&cpi->common.lfc_a,
sizeof(cpi->common.fc));
vpx_memcpy(cpi->common.fc.vp8_mode_contexts,
cpi->common.fc.mode_context_a,
sizeof(cpi->common.fc.vp8_mode_contexts));
} else {
vpx_memcpy(&cpi->common.fc,
&cpi->common.lfc,
sizeof(cpi->common.fc));
vpx_memcpy(cpi->common.fc.vp8_mode_contexts,
cpi->common.fc.mode_context,
sizeof(cpi->common.fc.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 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;
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;
}