ref: 9d7080e9f6bba3e840a98e5d9b73c538e30b5f05
dir: /vp9/encoder/vp9_craq.c/
/*
* Copyright (c) 2014 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 <limits.h>
#include <math.h>
#include "vp9/encoder/vp9_craq.h"
#include "vp9/common/vp9_seg_common.h"
#include "vp9/encoder/vp9_ratectrl.h"
#include "vp9/encoder/vp9_rdopt.h"
#include "vp9/encoder/vp9_segmentation.h"
// Check if we should turn off cyclic refresh based on bitrate condition.
static int apply_cyclic_refresh_bitrate(VP9_COMP *const cpi) {
// Turn off cyclic refresh if bits available per frame is not sufficiently
// larger than bit cost of segmentation. Segment map bit cost should scale
// with number of seg blocks, so compare available bits to number of blocks.
// Average bits available per frame = av_per_frame_bandwidth
// Number of (8x8) blocks in frame = mi_rows * mi_cols;
float factor = 0.5;
int number_blocks = cpi->common.mi_rows * cpi->common.mi_cols;
// The condition below corresponds to turning off at target bitrates:
// ~24kbps for CIF, 72kbps for VGA (at 30fps).
if (cpi->rc.av_per_frame_bandwidth < factor * number_blocks)
return 0;
else
return 1;
}
// Check if this coding block, of size bsize, should be considered for refresh
// (lower-qp coding). Decision can be based on various factors, such as
// size of the coding block (i.e., below min_block size rejected), coding
// mode, and rate/distortion.
static int candidate_refresh_aq(VP9_COMP *const cpi,
MODE_INFO *const mi,
int bsize,
int use_rd) {
CYCLIC_REFRESH *const cr = &cpi->cyclic_refresh;
if (use_rd) {
// If projected rate is below the thresh_rate (well below target,
// so undershoot expected), accept it for lower-qp coding.
if (cr->projected_rate_sb < cr->thresh_rate_sb)
return 1;
// Otherwise, reject the block for lower-qp coding if any of the following:
// 1) prediction block size is below min_block_size
// 2) mode is non-zero mv and projected distortion is above thresh_dist
// 3) mode is an intra-mode (we may want to allow some of this under
// another thresh_dist)
else if ((bsize < cr->min_block_size) ||
(mi->mbmi.mv[0].as_int != 0 &&
cr->projected_dist_sb > cr->thresh_dist_sb) ||
!is_inter_block(&mi->mbmi))
return 0;
else
return 1;
} else {
// Rate/distortion not used for update.
if ((bsize < cr->min_block_size) ||
(mi->mbmi.mv[0].as_int != 0) ||
!is_inter_block(&mi->mbmi))
return 0;
else
return 1;
}
}
// Prior to coding a given prediction block, of size bsize at (mi_row, mi_col),
// check if we should reset the segment_id, and update the cyclic_refresh map
// and segmentation map.
void vp9_update_segment_aq(VP9_COMP *const cpi,
MODE_INFO *const mi,
int mi_row,
int mi_col,
int bsize,
int use_rd) {
CYCLIC_REFRESH *const cr = &cpi->cyclic_refresh;
VP9_COMMON *const cm = &cpi->common;
const int bw = num_8x8_blocks_wide_lookup[bsize];
const int bh = num_8x8_blocks_high_lookup[bsize];
const int xmis = MIN(cm->mi_cols - mi_col, bw);
const int ymis = MIN(cm->mi_rows - mi_row, bh);
const int block_index = mi_row * cm->mi_cols + mi_col;
// Default is to not update the refresh map.
int new_map_value = cr->map[block_index];
int x = 0; int y = 0;
int current_segment = mi->mbmi.segment_id;
int refresh_this_block = candidate_refresh_aq(cpi, mi, bsize, use_rd);
// Check if we should reset the segment_id for this block.
if (current_segment && !refresh_this_block)
mi->mbmi.segment_id = 0;
// Update the cyclic refresh map, to be used for setting segmentation map
// for the next frame. If the block will be refreshed this frame, mark it
// as clean. The magnitude of the -ve influences how long before we consider
// it for refresh again.
if (mi->mbmi.segment_id == 1) {
new_map_value = -cr->time_for_refresh;
} else if (refresh_this_block) {
// Else if it is accepted as candidate for refresh, and has not already
// been refreshed (marked as 1) then mark it as a candidate for cleanup
// for future time (marked as 0), otherwise don't update it.
if (cr->map[block_index] == 1)
new_map_value = 0;
} else {
// Leave it marked as block that is not candidate for refresh.
new_map_value = 1;
}
// Update entries in the cyclic refresh map with new_map_value, and
// copy mbmi->segment_id into global segmentation map.
for (y = 0; y < ymis; y++)
for (x = 0; x < xmis; x++) {
cr->map[block_index + y * cm->mi_cols + x] = new_map_value;
cpi->segmentation_map[block_index + y * cm->mi_cols + x] =
mi->mbmi.segment_id;
}
// Keep track of actual number (in units of 8x8) of blocks in segment 1 used
// for encoding this frame.
if (mi->mbmi.segment_id)
cr->num_seg_blocks += xmis * ymis;
}
// Setup cyclic background refresh: set delta q and segmentation map.
void vp9_setup_cyclic_refresh_aq(VP9_COMP *const cpi) {
VP9_COMMON *const cm = &cpi->common;
CYCLIC_REFRESH *const cr = &cpi->cyclic_refresh;
struct segmentation *const seg = &cm->seg;
unsigned char *seg_map = cpi->segmentation_map;
int apply_cyclic_refresh = apply_cyclic_refresh_bitrate(cpi);
// Don't apply refresh on key frame or enhancement layer frames.
if (!apply_cyclic_refresh ||
(cpi->common.frame_type == KEY_FRAME) ||
(cpi->svc.temporal_layer_id > 0)) {
// Set segmentation map to 0 and disable.
vpx_memset(seg_map, 0, cm->mi_rows * cm->mi_cols);
vp9_disable_segmentation(&cm->seg);
if (cpi->common.frame_type == KEY_FRAME)
cr->mb_index = 0;
return;
} else {
int qindex_delta = 0;
int mbs_in_frame = cm->mi_rows * cm->mi_cols;
int i, x, y, block_count, bl_index, bl_index2;
int sum_map, new_value, mi_row, mi_col, xmis, ymis, qindex2;
// Rate target ratio to set q delta.
float rate_ratio_qdelta = 2.0;
vp9_clear_system_state();
// Some of these parameters may be set via codec-control function later.
cr->max_mbs_perframe = 10;
cr->max_qdelta_perc = 50;
cr->min_block_size = BLOCK_16X16;
cr->time_for_refresh = 1;
// Set rate threshold to some fraction of target (and scaled by 256).
cr->thresh_rate_sb = (cpi->rc.sb64_target_rate * 256) >> 2;
// Distortion threshold, quadratic in Q, scale factor to be adjusted.
cr->thresh_dist_sb = 8 * (int)(vp9_convert_qindex_to_q(cm->base_qindex) *
vp9_convert_qindex_to_q(cm->base_qindex));
if (cpi->sf.use_nonrd_pick_mode) {
// May want to be more conservative with thresholds in non-rd mode for now
// as rate/distortion are derived from model based on prediction residual.
cr->thresh_rate_sb = (cpi->rc.sb64_target_rate * 256) >> 3;
cr->thresh_dist_sb = 4 * (int)(vp9_convert_qindex_to_q(cm->base_qindex) *
vp9_convert_qindex_to_q(cm->base_qindex));
}
cr->num_seg_blocks = 0;
// Set up segmentation.
// Clear down the segment map.
vpx_memset(seg_map, 0, cm->mi_rows * cm->mi_cols);
vp9_enable_segmentation(&cm->seg);
vp9_clearall_segfeatures(seg);
// Select delta coding method.
seg->abs_delta = SEGMENT_DELTADATA;
// Note: setting temporal_update has no effect, as the seg-map coding method
// (temporal or spatial) is determined in vp9_choose_segmap_coding_method(),
// based on the coding cost of each method. For error_resilient mode on the
// last_frame_seg_map is set to 0, so if temporal coding is used, it is
// relative to 0 previous map.
// seg->temporal_update = 0;
// Segment 0 "Q" feature is disabled so it defaults to the baseline Q.
vp9_disable_segfeature(seg, 0, SEG_LVL_ALT_Q);
// Use segment 1 for in-frame Q adjustment.
vp9_enable_segfeature(seg, 1, SEG_LVL_ALT_Q);
// Set the q delta for segment 1.
qindex_delta = vp9_compute_qdelta_by_rate(cpi,
cm->base_qindex,
rate_ratio_qdelta);
// TODO(marpan): Incorporate the actual-vs-target rate over/undershoot from
// previous encoded frame.
if ((-qindex_delta) > cr->max_qdelta_perc * cm->base_qindex / 100) {
qindex_delta = -cr->max_qdelta_perc * cm->base_qindex / 100;
}
// Compute rd-mult for segment 1.
qindex2 = clamp(cm->base_qindex + cm->y_dc_delta_q + qindex_delta, 0, MAXQ);
cr->rdmult = vp9_compute_rd_mult(cpi, qindex2);
vp9_set_segdata(seg, 1, SEG_LVL_ALT_Q, qindex_delta);
// Number of target macroblocks to get the q delta (segment 1).
block_count = cr->max_mbs_perframe * mbs_in_frame / 100;
// Set the segmentation map: cycle through the macroblocks, starting at
// cr->mb_index, and stopping when either block_count blocks have been found
// to be refreshed, or we have passed through whole frame.
// Note the setting of seg_map below is done in two steps (one over 8x8)
// and then another over SB, in order to keep the value constant over SB.
// TODO(marpan): Do this in one pass in SB order.
assert(cr->mb_index < mbs_in_frame);
i = cr->mb_index;
do {
// If the macroblock is as a candidate for clean up then mark it
// for possible boost/refresh (segment 1). The segment id may get reset to
// 0 later if the macroblock gets coded anything other than ZEROMV.
if (cr->map[i] == 0) {
seg_map[i] = 1;
block_count--;
} else if (cr->map[i] < 0) {
cr->map[i]++;
}
i++;
if (i == mbs_in_frame) {
i = 0;
}
} while (block_count && i != cr->mb_index);
cr->mb_index = i;
// Enforce constant segment map over superblock.
for (mi_row = 0; mi_row < cm->mi_rows; mi_row += MI_BLOCK_SIZE)
for (mi_col = 0; mi_col < cm->mi_cols; mi_col += MI_BLOCK_SIZE) {
bl_index = mi_row * cm->mi_cols + mi_col;
xmis = num_8x8_blocks_wide_lookup[BLOCK_64X64];
ymis = num_8x8_blocks_high_lookup[BLOCK_64X64];
xmis = MIN(cm->mi_cols - mi_col, xmis);
ymis = MIN(cm->mi_rows - mi_row, ymis);
sum_map = 0;
for (y = 0; y < ymis; y++)
for (x = 0; x < xmis; x++) {
bl_index2 = bl_index + y * cm->mi_cols + x;
sum_map += seg_map[bl_index2];
}
new_value = 0;
// If segment is partial over superblock, reset.
if (sum_map > 0 && sum_map < xmis * ymis) {
if (sum_map < xmis * ymis / 2)
new_value = 0;
else
new_value = 1;
for (y = 0; y < ymis; y++)
for (x = 0; x < xmis; x++) {
bl_index2 = bl_index + y * cm->mi_cols + x;
seg_map[bl_index2] = new_value;
}
}
}
}
}