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Adapt strength of AQ2.

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Adapt the use of segmentation in AQ mode 2 based on
the ambient kf/arf/gf Q.

Disable segmentation where the rate per SB is very
low and overheads are likely to outweigh the benefits.

This patch reduces the -ve average metrics impact
of AQ mode 2 while allowing stronger 3 segment AQ
in some cases. Average improvement ~0.5-1.0%.

Change-Id: I5892dfcc7507c5cc6444531cc7fe17554cf8d0c7
This commit is contained in:
Paul Wilkins 2014-06-04 14:14:14 +01:00
parent 82dc1332af
commit adf4293e4e
2 changed files with 54 additions and 15 deletions
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67
vp9/encoder/vp9_aq_complexity.c
View File

@ -15,8 +15,19 @@
#include "vp9/encoder/vp9_segmentation.h"
static const double in_frame_q_adj_ratio[MAX_SEGMENTS] =
{1.0, 2.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0};
#define AQ_C_SEGMENTS 3
#define AQ_C_STRENGTHS 3
static const int aq_c_active_segments[AQ_C_STRENGTHS] = {1, 2, 3};
static const double aq_c_q_adj_factor[AQ_C_STRENGTHS][AQ_C_SEGMENTS] =
{{1.0, 1.0, 1.0}, {1.0, 2.0, 1.0}, {1.0, 1.5, 2.5}};
static const double aq_c_transitions[AQ_C_STRENGTHS][AQ_C_SEGMENTS] =
{{1.0, 1.0, 1.0}, {1.0, 0.25, 0.0}, {1.0, 0.5, 0.25}};
static int get_aq_c_strength(int q_index) {
// Approximate base quatizer (truncated to int)
int base_quant = vp9_ac_quant(q_index, 0) / 4;
return (base_quant > 20) + (base_quant > 45);
}
void vp9_setup_in_frame_q_adj(VP9_COMP *cpi) {
VP9_COMMON *const cm = &cpi->common;
@ -29,6 +40,8 @@ void vp9_setup_in_frame_q_adj(VP9_COMP *cpi) {
cpi->refresh_alt_ref_frame ||
(cpi->refresh_golden_frame && !cpi->rc.is_src_frame_alt_ref)) {
int segment;
const int aq_strength = get_aq_c_strength(cm->base_qindex);
const int active_segments = aq_c_active_segments[aq_strength];
// Clear down the segment map.
vpx_memset(cpi->segmentation_map, 0, cm->mi_rows * cm->mi_cols);
@ -36,9 +49,17 @@ void vp9_setup_in_frame_q_adj(VP9_COMP *cpi) {
// Clear down the complexity map used for rd.
vpx_memset(cpi->complexity_map, 0, cm->mi_rows * cm->mi_cols);
vp9_enable_segmentation(seg);
vp9_clearall_segfeatures(seg);
// Segmentation only makes sense if the target bits per SB is above a
// threshold. Below this the overheads will usually outweigh any benefit.
if (cpi->rc.sb64_target_rate < 256) {
vp9_disable_segmentation(seg);
return;
}
vp9_enable_segmentation(seg);
// Select delta coding method.
seg->abs_delta = SEGMENT_DELTADATA;
@ -46,14 +67,14 @@ void vp9_setup_in_frame_q_adj(VP9_COMP *cpi) {
vp9_disable_segfeature(seg, 0, SEG_LVL_ALT_Q);
// Use some of the segments for in frame Q adjustment.
for (segment = 1; segment < 2; segment++) {
for (segment = 1; segment < active_segments; ++segment) {
int qindex_delta =
vp9_compute_qdelta_by_rate(&cpi->rc, cm->frame_type, cm->base_qindex,
in_frame_q_adj_ratio[segment]);
aq_c_q_adj_factor[aq_strength][segment]);
// For AQ mode 2, we dont allow Q0 in a segment if the base Q is not 0.
// Q0 (lossless) implies 4x4 only and in AQ mode 2 a segment Q delta
// is sometimes applied without going back around the rd loop.
// For AQ complexity mode, we dont allow Q0 in a segment if the base
// Q is not 0. Q0 (lossless) implies 4x4 only and in AQ mode 2 a segment
// Q delta is sometimes applied without going back around the rd loop.
// This could lead to an illegal combination of partition size and q.
if ((cm->base_qindex != 0) && ((cm->base_qindex + qindex_delta) == 0)) {
qindex_delta = -cm->base_qindex + 1;
@ -66,10 +87,15 @@ void vp9_setup_in_frame_q_adj(VP9_COMP *cpi) {
}
}
// Select a segment for the current SB64
// Select a segment for the current SB64 block.
// The choice of segment for a block depends on the ratio of the projected
// bits for the block vs a target average.
// An "aq_strength" value determines how many segments are supported,
// the set of transition points to use and the extent of the quantizer
// adjustment for each segment (configured in vp9_setup_in_frame_q_adj()).
void vp9_select_in_frame_q_segment(VP9_COMP *cpi,
int mi_row, int mi_col,
int output_enabled, int projected_rate) {
int mi_row, int mi_col,
int output_enabled, int projected_rate) {
VP9_COMMON *const cm = &cpi->common;
const int mi_offset = mi_row * cm->mi_cols + mi_col;
@ -89,11 +115,22 @@ void vp9_select_in_frame_q_segment(VP9_COMP *cpi,
// It is converted to bits * 256 units.
const int target_rate = (cpi->rc.sb64_target_rate * xmis * ymis * 256) /
(bw * bh);
const int aq_strength = get_aq_c_strength(cm->base_qindex);
const int active_segments = aq_c_active_segments[aq_strength];
if (projected_rate < (target_rate / 4)) {
segment = 1;
} else {
segment = 0;
// The number of segments considered and the transition points used to
// select them is determined by the "aq_strength" value.
// Currently this loop only supports segments that reduce Q (i.e. where
// there is undershoot.
// The loop counts down towards segment 0 which is the default segment
// with no Q adjustment.
segment = active_segments - 1;
while (segment > 0) {
if (projected_rate <
(target_rate * aq_c_transitions[aq_strength][segment])) {
break;
}
--segment;
}
if (target_rate > 0) {

2
vp9/encoder/vp9_segmentation.c
View File

@ -27,6 +27,8 @@ void vp9_enable_segmentation(struct segmentation *seg) {
void vp9_disable_segmentation(struct segmentation *seg) {
seg->enabled = 0;
seg->update_map = 0;
seg->update_data = 0;
}
void vp9_set_segment_data(struct segmentation *seg,