2 * Copyright (c) 2014 The WebM project authors. All Rights Reserved.
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
14 #include "vp9/encoder/vp9_aq_cyclicrefresh.h"
16 #include "vp9/common/vp9_seg_common.h"
18 #include "vp9/encoder/vp9_ratectrl.h"
19 #include "vp9/encoder/vp9_segmentation.h"
21 struct CYCLIC_REFRESH {
22 // Percentage of blocks per frame that are targeted as candidates
23 // for cyclic refresh.
25 // Maximum q-delta as percentage of base q.
27 // Block size below which we don't apply cyclic refresh.
28 BLOCK_SIZE min_block_size;
29 // Superblock starting index for cycling through the frame.
31 // Controls how long block will need to wait to be refreshed again, in
32 // excess of the cycle time, i.e., in the case of all zero motion, block
33 // will be refreshed every (100/percent_refresh + time_for_refresh) frames.
35 // // Target number of (8x8) blocks that are set for delta-q (segment 1).
36 int target_num_seg_blocks;
37 // Actual number of (8x8) blocks that were applied delta-q (segment 1).
38 int actual_num_seg_blocks;
39 // RD mult. parameters for segment 1.
41 // Cyclic refresh map.
43 // Thresholds applied to projected rate/distortion of the superblock.
44 int64_t thresh_rate_sb;
45 int64_t thresh_dist_sb;
46 // Rate target ratio to set q delta.
47 double rate_ratio_qdelta;
50 CYCLIC_REFRESH *vp9_cyclic_refresh_alloc(int mi_rows, int mi_cols) {
51 CYCLIC_REFRESH *const cr = vpx_calloc(1, sizeof(*cr));
55 cr->map = vpx_calloc(mi_rows * mi_cols, sizeof(*cr->map));
56 if (cr->map == NULL) {
64 void vp9_cyclic_refresh_free(CYCLIC_REFRESH *cr) {
69 // Check if we should turn off cyclic refresh based on bitrate condition.
70 static int apply_cyclic_refresh_bitrate(const VP9_COMMON *cm,
71 const RATE_CONTROL *rc) {
72 // Turn off cyclic refresh if bits available per frame is not sufficiently
73 // larger than bit cost of segmentation. Segment map bit cost should scale
74 // with number of seg blocks, so compare available bits to number of blocks.
75 // Average bits available per frame = avg_frame_bandwidth
76 // Number of (8x8) blocks in frame = mi_rows * mi_cols;
77 const float factor = 0.5;
78 const int number_blocks = cm->mi_rows * cm->mi_cols;
79 // The condition below corresponds to turning off at target bitrates:
80 // ~24kbps for CIF, 72kbps for VGA (at 30fps).
81 // Also turn off at very small frame sizes, to avoid too large fraction of
82 // superblocks to be refreshed per frame. Threshold below is less than QCIF.
83 if (rc->avg_frame_bandwidth < factor * number_blocks ||
84 number_blocks / 64 < 5)
90 // Check if this coding block, of size bsize, should be considered for refresh
91 // (lower-qp coding). Decision can be based on various factors, such as
92 // size of the coding block (i.e., below min_block size rejected), coding
93 // mode, and rate/distortion.
94 static int candidate_refresh_aq(const CYCLIC_REFRESH *cr,
95 const MB_MODE_INFO *mbmi,
96 BLOCK_SIZE bsize, int use_rd,
99 MV mv = mbmi->mv[0].as_mv;
100 // If projected rate is below the thresh_rate (well below target,
101 // so undershoot expected), accept it for lower-qp coding.
102 if (rate_sb < cr->thresh_rate_sb)
104 // Otherwise, reject the block for lower-qp coding if any of the following:
105 // 1) mode uses large mv
106 // 2) mode is an intra-mode (we may want to allow some of this under
107 // another thresh_dist)
108 else if (mv.row > 32 || mv.row < -32 ||
109 mv.col > 32 || mv.col < -32 || !is_inter_block(mbmi))
114 // Rate/distortion not used for update.
115 if (bsize < cr->min_block_size ||
116 mbmi->mv[0].as_int != 0 ||
117 !is_inter_block(mbmi))
124 // Compute delta-q for the segment.
125 static int compute_deltaq(const VP9_COMP *cpi, int q) {
126 const CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
127 const RATE_CONTROL *const rc = &cpi->rc;
128 int deltaq = vp9_compute_qdelta_by_rate(rc, cpi->common.frame_type,
129 q, cr->rate_ratio_qdelta,
130 cpi->common.bit_depth);
131 if ((-deltaq) > cr->max_qdelta_perc * q / 100) {
132 deltaq = -cr->max_qdelta_perc * q / 100;
137 // For the just encoded frame, estimate the bits, incorporating the delta-q
138 // from segment 1. This function is called in the postencode (called from
139 // rc_update_rate_correction_factors()).
140 int vp9_cyclic_refresh_estimate_bits_at_q(const VP9_COMP *cpi,
141 double correction_factor) {
142 const VP9_COMMON *const cm = &cpi->common;
143 const CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
146 int num8x8bl = mbs << 2;
147 // Weight for segment 1: use actual number of blocks refreshed in
148 // previous/just encoded frame. Note number of blocks here is in 8x8 units.
149 double weight_segment = (double)cr->actual_num_seg_blocks / num8x8bl;
150 // Compute delta-q that was used in the just encoded frame.
151 int deltaq = compute_deltaq(cpi, cm->base_qindex);
152 // Take segment weighted average for estimated bits.
153 estimated_bits = (int)((1.0 - weight_segment) *
154 vp9_estimate_bits_at_q(cm->frame_type, cm->base_qindex, mbs,
155 correction_factor, cm->bit_depth) +
157 vp9_estimate_bits_at_q(cm->frame_type, cm->base_qindex + deltaq, mbs,
158 correction_factor, cm->bit_depth));
159 return estimated_bits;
162 // Prior to encoding the frame, estimate the bits per mb, for a given q = i and
163 // a corresponding delta-q (for segment 1). This function is called in the
164 // rc_regulate_q() to set the base qp index.
165 int vp9_cyclic_refresh_rc_bits_per_mb(const VP9_COMP *cpi, int i,
166 double correction_factor) {
167 const VP9_COMMON *const cm = &cpi->common;
168 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
170 int num8x8bl = cm->MBs << 2;
171 // Weight for segment 1 prior to encoding: take the target number for the
172 // frame to be encoded. Number of blocks here is in 8x8 units.
173 // Note that this is called in rc_regulate_q, which is called before the
174 // cyclic_refresh_setup (which sets cr->target_num_seg_blocks). So a mismatch
175 // may occur between the cr->target_num_seg_blocks value here and the
176 // cr->target_num_seg_block set for encoding the frame. For the current use
177 // case of fixed cr->percent_refresh and cr->time_for_refresh = 0, mismatch
178 // does not occur/is very small.
179 double weight_segment = (double)cr->target_num_seg_blocks / num8x8bl;
180 // Compute delta-q corresponding to qindex i.
181 int deltaq = compute_deltaq(cpi, i);
182 // Take segment weighted average for bits per mb.
183 bits_per_mb = (int)((1.0 - weight_segment) *
184 vp9_rc_bits_per_mb(cm->frame_type, i, correction_factor, cm->bit_depth) +
186 vp9_rc_bits_per_mb(cm->frame_type, i + deltaq, correction_factor,
191 // Prior to coding a given prediction block, of size bsize at (mi_row, mi_col),
192 // check if we should reset the segment_id, and update the cyclic_refresh map
193 // and segmentation map.
194 void vp9_cyclic_refresh_update_segment(VP9_COMP *const cpi,
195 MB_MODE_INFO *const mbmi,
196 int mi_row, int mi_col,
197 BLOCK_SIZE bsize, int use_rd,
199 const VP9_COMMON *const cm = &cpi->common;
200 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
201 const int bw = num_8x8_blocks_wide_lookup[bsize];
202 const int bh = num_8x8_blocks_high_lookup[bsize];
203 const int xmis = MIN(cm->mi_cols - mi_col, bw);
204 const int ymis = MIN(cm->mi_rows - mi_row, bh);
205 const int block_index = mi_row * cm->mi_cols + mi_col;
206 const int refresh_this_block = candidate_refresh_aq(cr, mbmi, bsize, use_rd,
208 // Default is to not update the refresh map.
209 int new_map_value = cr->map[block_index];
210 int x = 0; int y = 0;
212 // Check if we should reset the segment_id for this block.
213 if (mbmi->segment_id > 0 && !refresh_this_block)
214 mbmi->segment_id = 0;
216 // Update the cyclic refresh map, to be used for setting segmentation map
217 // for the next frame. If the block will be refreshed this frame, mark it
218 // as clean. The magnitude of the -ve influences how long before we consider
219 // it for refresh again.
220 if (mbmi->segment_id == 1) {
221 new_map_value = -cr->time_for_refresh;
222 } else if (refresh_this_block) {
223 // Else if it is accepted as candidate for refresh, and has not already
224 // been refreshed (marked as 1) then mark it as a candidate for cleanup
225 // for future time (marked as 0), otherwise don't update it.
226 if (cr->map[block_index] == 1)
229 // Leave it marked as block that is not candidate for refresh.
233 // Update entries in the cyclic refresh map with new_map_value, and
234 // copy mbmi->segment_id into global segmentation map.
235 for (y = 0; y < ymis; y++)
236 for (x = 0; x < xmis; x++) {
237 cr->map[block_index + y * cm->mi_cols + x] = new_map_value;
238 cpi->segmentation_map[block_index + y * cm->mi_cols + x] =
243 // Update the actual number of blocks that were applied the segment delta q.
244 void vp9_cyclic_refresh_update_actual_count(struct VP9_COMP *const cpi) {
245 VP9_COMMON *const cm = &cpi->common;
246 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
247 unsigned char *const seg_map = cpi->segmentation_map;
249 cr->actual_num_seg_blocks = 0;
250 for (mi_row = 0; mi_row < cm->mi_rows; mi_row++)
251 for (mi_col = 0; mi_col < cm->mi_cols; mi_col++) {
252 if (seg_map[mi_row * cm->mi_cols + mi_col] == 1)
253 cr->actual_num_seg_blocks++;
257 // Update the segmentation map, and related quantities: cyclic refresh map,
258 // refresh sb_index, and target number of blocks to be refreshed.
259 void vp9_cyclic_refresh_update_map(VP9_COMP *const cpi) {
260 VP9_COMMON *const cm = &cpi->common;
261 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
262 unsigned char *const seg_map = cpi->segmentation_map;
263 int i, block_count, bl_index, sb_rows, sb_cols, sbs_in_frame;
264 int xmis, ymis, x, y;
265 vpx_memset(seg_map, 0, cm->mi_rows * cm->mi_cols);
266 sb_cols = (cm->mi_cols + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
267 sb_rows = (cm->mi_rows + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
268 sbs_in_frame = sb_cols * sb_rows;
269 // Number of target blocks to get the q delta (segment 1).
270 block_count = cr->percent_refresh * cm->mi_rows * cm->mi_cols / 100;
271 // Set the segmentation map: cycle through the superblocks, starting at
272 // cr->mb_index, and stopping when either block_count blocks have been found
273 // to be refreshed, or we have passed through whole frame.
274 assert(cr->sb_index < sbs_in_frame);
276 cr->target_num_seg_blocks = 0;
279 // Get the mi_row/mi_col corresponding to superblock index i.
280 int sb_row_index = (i / sb_cols);
281 int sb_col_index = i - sb_row_index * sb_cols;
282 int mi_row = sb_row_index * MI_BLOCK_SIZE;
283 int mi_col = sb_col_index * MI_BLOCK_SIZE;
284 assert(mi_row >= 0 && mi_row < cm->mi_rows);
285 assert(mi_col >= 0 && mi_col < cm->mi_cols);
286 bl_index = mi_row * cm->mi_cols + mi_col;
287 // Loop through all 8x8 blocks in superblock and update map.
288 xmis = MIN(cm->mi_cols - mi_col,
289 num_8x8_blocks_wide_lookup[BLOCK_64X64]);
290 ymis = MIN(cm->mi_rows - mi_row,
291 num_8x8_blocks_high_lookup[BLOCK_64X64]);
292 for (y = 0; y < ymis; y++) {
293 for (x = 0; x < xmis; x++) {
294 const int bl_index2 = bl_index + y * cm->mi_cols + x;
295 // If the block is as a candidate for clean up then mark it
296 // for possible boost/refresh (segment 1). The segment id may get
297 // reset to 0 later if block gets coded anything other than ZEROMV.
298 if (cr->map[bl_index2] == 0) {
300 } else if (cr->map[bl_index2] < 0) {
301 cr->map[bl_index2]++;
305 // Enforce constant segment over superblock.
306 // If segment is at least half of superblock, set to 1.
307 if (sum_map >= xmis * ymis / 2) {
308 for (y = 0; y < ymis; y++)
309 for (x = 0; x < xmis; x++) {
310 seg_map[bl_index + y * cm->mi_cols + x] = 1;
312 cr->target_num_seg_blocks += xmis * ymis;
315 if (i == sbs_in_frame) {
318 } while (cr->target_num_seg_blocks < block_count && i != cr->sb_index);
322 // Set/update global/frame level cyclic refresh parameters.
323 void vp9_cyclic_refresh_update_parameters(VP9_COMP *const cpi) {
324 const RATE_CONTROL *const rc = &cpi->rc;
325 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
326 cr->percent_refresh = 10;
327 // Use larger delta-qp (increase rate_ratio_qdelta) for first few (~4)
328 // periods of the refresh cycle, after a key frame. This corresponds to ~40
329 // frames with cr->percent_refresh = 10.
330 if (rc->frames_since_key < 40)
331 cr->rate_ratio_qdelta = 3.0;
333 cr->rate_ratio_qdelta = 2.0;
336 // Setup cyclic background refresh: set delta q and segmentation map.
337 void vp9_cyclic_refresh_setup(VP9_COMP *const cpi) {
338 VP9_COMMON *const cm = &cpi->common;
339 const RATE_CONTROL *const rc = &cpi->rc;
340 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
341 struct segmentation *const seg = &cm->seg;
342 const int apply_cyclic_refresh = apply_cyclic_refresh_bitrate(cm, rc);
343 // Don't apply refresh on key frame or enhancement layer frames.
344 if (!apply_cyclic_refresh ||
345 (cm->frame_type == KEY_FRAME) ||
346 (cpi->svc.temporal_layer_id > 0) ||
347 (cpi->svc.spatial_layer_id > 0)) {
348 // Set segmentation map to 0 and disable.
349 unsigned char *const seg_map = cpi->segmentation_map;
350 vpx_memset(seg_map, 0, cm->mi_rows * cm->mi_cols);
351 vp9_disable_segmentation(&cm->seg);
352 if (cm->frame_type == KEY_FRAME)
356 int qindex_delta = 0;
358 const double q = vp9_convert_qindex_to_q(cm->base_qindex, cm->bit_depth);
359 vp9_clear_system_state();
360 cr->max_qdelta_perc = 50;
361 cr->min_block_size = BLOCK_8X8;
362 cr->time_for_refresh = 0;
363 // Set rate threshold to some fraction of target (and scaled by 256).
364 cr->thresh_rate_sb = (rc->sb64_target_rate * 256) >> 2;
365 // Distortion threshold, quadratic in Q, scale factor to be adjusted.
366 cr->thresh_dist_sb = 8 * (int)(q * q);
367 if (cpi->sf.use_nonrd_pick_mode) {
368 // May want to be more conservative with thresholds in non-rd mode for now
369 // as rate/distortion are derived from model based on prediction residual.
370 cr->thresh_rate_sb = (rc->sb64_target_rate * 256);
371 cr->thresh_dist_sb = 16 * (int)(q * q);
374 // Set up segmentation.
375 // Clear down the segment map.
376 vp9_enable_segmentation(&cm->seg);
377 vp9_clearall_segfeatures(seg);
378 // Select delta coding method.
379 seg->abs_delta = SEGMENT_DELTADATA;
381 // Note: setting temporal_update has no effect, as the seg-map coding method
382 // (temporal or spatial) is determined in vp9_choose_segmap_coding_method(),
383 // based on the coding cost of each method. For error_resilient mode on the
384 // last_frame_seg_map is set to 0, so if temporal coding is used, it is
385 // relative to 0 previous map.
386 // seg->temporal_update = 0;
388 // Segment 0 "Q" feature is disabled so it defaults to the baseline Q.
389 vp9_disable_segfeature(seg, 0, SEG_LVL_ALT_Q);
390 // Use segment 1 for in-frame Q adjustment.
391 vp9_enable_segfeature(seg, 1, SEG_LVL_ALT_Q);
393 // Set the q delta for segment 1.
394 qindex_delta = compute_deltaq(cpi, cm->base_qindex);
396 // Compute rd-mult for segment 1.
397 qindex2 = clamp(cm->base_qindex + cm->y_dc_delta_q + qindex_delta, 0, MAXQ);
398 cr->rdmult = vp9_compute_rd_mult(cpi, qindex2);
400 vp9_set_segdata(seg, 1, SEG_LVL_ALT_Q, qindex_delta);
402 // Update the segmentation and refresh map.
403 vp9_cyclic_refresh_update_map(cpi);
407 int vp9_cyclic_refresh_get_rdmult(const CYCLIC_REFRESH *cr) {