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 // Superblock starting index for cycling through the frame.
29 // Controls how long block will need to wait to be refreshed again, in
30 // excess of the cycle time, i.e., in the case of all zero motion, block
31 // will be refreshed every (100/percent_refresh + time_for_refresh) frames.
33 // Target number of (8x8) blocks that are set for delta-q.
34 int target_num_seg_blocks;
35 // Actual number of (8x8) blocks that were applied delta-q.
36 int actual_num_seg1_blocks;
37 int actual_num_seg2_blocks;
38 // RD mult. parameters for segment 1.
40 // Cyclic refresh map.
42 // Thresholds applied to the projected rate/distortion of the coding block,
43 // when deciding whether block should be refreshed.
44 int64_t thresh_rate_sb;
45 int64_t thresh_dist_sb;
46 // Threshold applied to the motion vector (in units of 1/8 pel) of the
47 // coding block, when deciding whether block should be refreshed.
48 int16_t motion_thresh;
49 // Rate target ratio to set q delta.
50 double rate_ratio_qdelta;
51 // Boost factor for rate target ratio, for segment CR_SEGMENT_ID_BOOST2.
52 double rate_boost_fac;
53 double low_content_avg;
54 int qindex_delta_seg1;
55 int qindex_delta_seg2;
58 CYCLIC_REFRESH *vp9_cyclic_refresh_alloc(int mi_rows, int mi_cols) {
59 CYCLIC_REFRESH *const cr = vpx_calloc(1, sizeof(*cr));
63 cr->map = vpx_calloc(mi_rows * mi_cols, sizeof(*cr->map));
64 if (cr->map == NULL) {
72 void vp9_cyclic_refresh_free(CYCLIC_REFRESH *cr) {
77 // Check if we should turn off cyclic refresh based on bitrate condition.
78 static int apply_cyclic_refresh_bitrate(const VP9_COMMON *cm,
79 const RATE_CONTROL *rc) {
80 // Turn off cyclic refresh if bits available per frame is not sufficiently
81 // larger than bit cost of segmentation. Segment map bit cost should scale
82 // with number of seg blocks, so compare available bits to number of blocks.
83 // Average bits available per frame = avg_frame_bandwidth
84 // Number of (8x8) blocks in frame = mi_rows * mi_cols;
85 const float factor = 0.25;
86 const int number_blocks = cm->mi_rows * cm->mi_cols;
87 // The condition below corresponds to turning off at target bitrates:
88 // (at 30fps), ~12kbps for CIF, 36kbps for VGA, 100kps for HD/720p.
89 // Also turn off at very small frame sizes, to avoid too large fraction of
90 // superblocks to be refreshed per frame. Threshold below is less than QCIF.
91 if (rc->avg_frame_bandwidth < factor * number_blocks ||
92 number_blocks / 64 < 5)
98 // Check if this coding block, of size bsize, should be considered for refresh
99 // (lower-qp coding). Decision can be based on various factors, such as
100 // size of the coding block (i.e., below min_block size rejected), coding
101 // mode, and rate/distortion.
102 static int candidate_refresh_aq(const CYCLIC_REFRESH *cr,
103 const MB_MODE_INFO *mbmi,
107 MV mv = mbmi->mv[0].as_mv;
108 // Reject the block for lower-qp coding if projected distortion
109 // is above the threshold, and any of the following is true:
110 // 1) mode uses large mv
111 // 2) mode is an intra-mode
112 // Otherwise accept for refresh.
113 if (dist > cr->thresh_dist_sb &&
114 (mv.row > cr->motion_thresh || mv.row < -cr->motion_thresh ||
115 mv.col > cr->motion_thresh || mv.col < -cr->motion_thresh ||
116 !is_inter_block(mbmi)))
117 return CR_SEGMENT_ID_BASE;
118 else if (bsize >= BLOCK_16X16 &&
119 rate < cr->thresh_rate_sb &&
120 is_inter_block(mbmi) &&
121 mbmi->mv[0].as_int == 0)
122 // More aggressive delta-q for bigger blocks with zero motion.
123 return CR_SEGMENT_ID_BOOST2;
125 return CR_SEGMENT_ID_BOOST1;
128 // Compute delta-q for the segment.
129 static int compute_deltaq(const VP9_COMP *cpi, int q, double rate_factor) {
130 const CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
131 const RATE_CONTROL *const rc = &cpi->rc;
132 int deltaq = vp9_compute_qdelta_by_rate(rc, cpi->common.frame_type,
134 cpi->common.bit_depth);
135 if ((-deltaq) > cr->max_qdelta_perc * q / 100) {
136 deltaq = -cr->max_qdelta_perc * q / 100;
141 // For the just encoded frame, estimate the bits, incorporating the delta-q
142 // from non-base segment. For now ignore effect of multiple segments
143 // (with different delta-q). Note this function is called in the postencode
144 // (called from rc_update_rate_correction_factors()).
145 int vp9_cyclic_refresh_estimate_bits_at_q(const VP9_COMP *cpi,
146 double correction_factor) {
147 const VP9_COMMON *const cm = &cpi->common;
148 const CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
151 int num8x8bl = mbs << 2;
152 // Weight for non-base segments: use actual number of blocks refreshed in
153 // previous/just encoded frame. Note number of blocks here is in 8x8 units.
154 double weight_segment1 = (double)cr->actual_num_seg1_blocks / num8x8bl;
155 double weight_segment2 = (double)cr->actual_num_seg2_blocks / num8x8bl;
156 // Take segment weighted average for estimated bits.
157 estimated_bits = (int)((1.0 - weight_segment1 - weight_segment2) *
158 vp9_estimate_bits_at_q(cm->frame_type, cm->base_qindex, mbs,
159 correction_factor, cm->bit_depth) +
161 vp9_estimate_bits_at_q(cm->frame_type,
162 cm->base_qindex + cr->qindex_delta_seg1, mbs,
163 correction_factor, cm->bit_depth) +
165 vp9_estimate_bits_at_q(cm->frame_type,
166 cm->base_qindex + cr->qindex_delta_seg2, mbs,
167 correction_factor, cm->bit_depth));
168 return estimated_bits;
171 // Prior to encoding the frame, estimate the bits per mb, for a given q = i and
172 // a corresponding delta-q (for segment 1). This function is called in the
173 // rc_regulate_q() to set the base qp index.
174 // Note: the segment map is set to either 0/CR_SEGMENT_ID_BASE (no refresh) or
175 // to 1/CR_SEGMENT_ID_BOOST1 (refresh) for each superblock, prior to encoding.
176 int vp9_cyclic_refresh_rc_bits_per_mb(const VP9_COMP *cpi, int i,
177 double correction_factor) {
178 const VP9_COMMON *const cm = &cpi->common;
179 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
181 int num8x8bl = cm->MBs << 2;
182 // Weight for segment prior to encoding: take the average of the target
183 // number for the frame to be encoded and the actual from the previous frame.
184 double weight_segment = (double)((cr->target_num_seg_blocks +
185 cr->actual_num_seg1_blocks + cr->actual_num_seg2_blocks) >> 1) /
187 // Compute delta-q corresponding to qindex i.
188 int deltaq = compute_deltaq(cpi, i, cr->rate_ratio_qdelta);
189 // Take segment weighted average for bits per mb.
190 bits_per_mb = (int)((1.0 - weight_segment) *
191 vp9_rc_bits_per_mb(cm->frame_type, i, correction_factor, cm->bit_depth) +
193 vp9_rc_bits_per_mb(cm->frame_type, i + deltaq, correction_factor,
198 // Prior to coding a given prediction block, of size bsize at (mi_row, mi_col),
199 // check if we should reset the segment_id, and update the cyclic_refresh map
200 // and segmentation map.
201 void vp9_cyclic_refresh_update_segment(VP9_COMP *const cpi,
202 MB_MODE_INFO *const mbmi,
203 int mi_row, int mi_col,
208 const VP9_COMMON *const cm = &cpi->common;
209 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
210 const int bw = num_8x8_blocks_wide_lookup[bsize];
211 const int bh = num_8x8_blocks_high_lookup[bsize];
212 const int xmis = MIN(cm->mi_cols - mi_col, bw);
213 const int ymis = MIN(cm->mi_rows - mi_row, bh);
214 const int block_index = mi_row * cm->mi_cols + mi_col;
215 const int refresh_this_block = candidate_refresh_aq(cr, mbmi, rate, dist,
217 // Default is to not update the refresh map.
218 int new_map_value = cr->map[block_index];
219 int x = 0; int y = 0;
221 // If this block is labeled for refresh, check if we should reset the
223 if (cyclic_refresh_segment_id_boosted(mbmi->segment_id)) {
224 mbmi->segment_id = refresh_this_block;
225 // Reset segment_id if will be skipped.
227 mbmi->segment_id = CR_SEGMENT_ID_BASE;
230 // Update the cyclic refresh map, to be used for setting segmentation map
231 // for the next frame. If the block will be refreshed this frame, mark it
232 // as clean. The magnitude of the -ve influences how long before we consider
233 // it for refresh again.
234 if (cyclic_refresh_segment_id_boosted(mbmi->segment_id)) {
235 new_map_value = -cr->time_for_refresh;
236 } else if (refresh_this_block) {
237 // Else if it is accepted as candidate for refresh, and has not already
238 // been refreshed (marked as 1) then mark it as a candidate for cleanup
239 // for future time (marked as 0), otherwise don't update it.
240 if (cr->map[block_index] == 1)
243 // Leave it marked as block that is not candidate for refresh.
247 // Update entries in the cyclic refresh map with new_map_value, and
248 // copy mbmi->segment_id into global segmentation map.
249 for (y = 0; y < ymis; y++)
250 for (x = 0; x < xmis; x++) {
251 cr->map[block_index + y * cm->mi_cols + x] = new_map_value;
252 cpi->segmentation_map[block_index + y * cm->mi_cols + x] =
257 // Update the actual number of blocks that were applied the segment delta q.
258 void vp9_cyclic_refresh_postencode(VP9_COMP *const cpi) {
259 VP9_COMMON *const cm = &cpi->common;
260 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
261 unsigned char *const seg_map = cpi->segmentation_map;
263 cr->actual_num_seg1_blocks = 0;
264 cr->actual_num_seg2_blocks = 0;
265 for (mi_row = 0; mi_row < cm->mi_rows; mi_row++)
266 for (mi_col = 0; mi_col < cm->mi_cols; mi_col++) {
267 if (cyclic_refresh_segment_id(
268 seg_map[mi_row * cm->mi_cols + mi_col]) == CR_SEGMENT_ID_BOOST1)
269 cr->actual_num_seg1_blocks++;
270 else if (cyclic_refresh_segment_id(
271 seg_map[mi_row * cm->mi_cols + mi_col]) == CR_SEGMENT_ID_BOOST2)
272 cr->actual_num_seg2_blocks++;
276 // Set golden frame update interval, for non-svc 1 pass CBR mode.
277 void vp9_cyclic_refresh_set_golden_update(VP9_COMP *const cpi) {
278 RATE_CONTROL *const rc = &cpi->rc;
279 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
280 // Set minimum gf_interval for GF update to a multiple (== 2) of refresh
281 // period. Depending on past encoding stats, GF flag may be reset and update
282 // may not occur until next baseline_gf_interval.
283 if (cr->percent_refresh > 0)
284 rc->baseline_gf_interval = 4 * (100 / cr->percent_refresh);
286 rc->baseline_gf_interval = 40;
289 // Update some encoding stats (from the just encoded frame). If this frame's
290 // background has high motion, refresh the golden frame. Otherwise, if the
291 // golden reference is to be updated check if we should NOT update the golden
293 void vp9_cyclic_refresh_check_golden_update(VP9_COMP *const cpi) {
294 VP9_COMMON *const cm = &cpi->common;
295 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
297 double fraction_low = 0.0;
298 int low_content_frame = 0;
300 MODE_INFO **mi = cm->mi_grid_visible;
301 RATE_CONTROL *const rc = &cpi->rc;
302 const int rows = cm->mi_rows, cols = cm->mi_cols;
303 int cnt1 = 0, cnt2 = 0;
304 int force_gf_refresh = 0;
306 for (mi_row = 0; mi_row < rows; mi_row++) {
307 for (mi_col = 0; mi_col < cols; mi_col++) {
308 int16_t abs_mvr = mi[0]->mbmi.mv[0].as_mv.row >= 0 ?
309 mi[0]->mbmi.mv[0].as_mv.row : -1 * mi[0]->mbmi.mv[0].as_mv.row;
310 int16_t abs_mvc = mi[0]->mbmi.mv[0].as_mv.col >= 0 ?
311 mi[0]->mbmi.mv[0].as_mv.col : -1 * mi[0]->mbmi.mv[0].as_mv.col;
313 // Calculate the motion of the background.
314 if (abs_mvr <= 16 && abs_mvc <= 16) {
316 if (abs_mvr == 0 && abs_mvc == 0)
321 // Accumulate low_content_frame.
322 if (cr->map[mi_row * cols + mi_col] < 1)
328 // For video conference clips, if the background has high motion in current
329 // frame because of the camera movement, set this frame as the golden frame.
330 // Use 70% and 5% as the thresholds for golden frame refreshing.
331 if (cnt1 * 10 > (70 * rows * cols) && cnt2 * 20 < cnt1) {
332 vp9_cyclic_refresh_set_golden_update(cpi);
333 rc->frames_till_gf_update_due = rc->baseline_gf_interval;
335 if (rc->frames_till_gf_update_due > rc->frames_to_key)
336 rc->frames_till_gf_update_due = rc->frames_to_key;
337 cpi->refresh_golden_frame = 1;
338 force_gf_refresh = 1;
342 (double)low_content_frame / (rows * cols);
344 cr->low_content_avg = (fraction_low + 3 * cr->low_content_avg) / 4;
345 if (!force_gf_refresh && cpi->refresh_golden_frame == 1) {
346 // Don't update golden reference if the amount of low_content for the
347 // current encoded frame is small, or if the recursive average of the
348 // low_content over the update interval window falls below threshold.
349 if (fraction_low < 0.8 || cr->low_content_avg < 0.7)
350 cpi->refresh_golden_frame = 0;
351 // Reset for next internal.
352 cr->low_content_avg = fraction_low;
356 // Update the segmentation map, and related quantities: cyclic refresh map,
357 // refresh sb_index, and target number of blocks to be refreshed.
358 // The map is set to either 0/CR_SEGMENT_ID_BASE (no refresh) or to
359 // 1/CR_SEGMENT_ID_BOOST1 (refresh) for each superblock.
360 // Blocks labeled as BOOST1 may later get set to BOOST2 (during the
361 // encoding of the superblock).
362 static void cyclic_refresh_update_map(VP9_COMP *const cpi) {
363 VP9_COMMON *const cm = &cpi->common;
364 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
365 unsigned char *const seg_map = cpi->segmentation_map;
366 int i, block_count, bl_index, sb_rows, sb_cols, sbs_in_frame;
367 int xmis, ymis, x, y;
368 memset(seg_map, CR_SEGMENT_ID_BASE, cm->mi_rows * cm->mi_cols);
369 sb_cols = (cm->mi_cols + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
370 sb_rows = (cm->mi_rows + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
371 sbs_in_frame = sb_cols * sb_rows;
372 // Number of target blocks to get the q delta (segment 1).
373 block_count = cr->percent_refresh * cm->mi_rows * cm->mi_cols / 100;
374 // Set the segmentation map: cycle through the superblocks, starting at
375 // cr->mb_index, and stopping when either block_count blocks have been found
376 // to be refreshed, or we have passed through whole frame.
377 assert(cr->sb_index < sbs_in_frame);
379 cr->target_num_seg_blocks = 0;
382 // Get the mi_row/mi_col corresponding to superblock index i.
383 int sb_row_index = (i / sb_cols);
384 int sb_col_index = i - sb_row_index * sb_cols;
385 int mi_row = sb_row_index * MI_BLOCK_SIZE;
386 int mi_col = sb_col_index * MI_BLOCK_SIZE;
387 assert(mi_row >= 0 && mi_row < cm->mi_rows);
388 assert(mi_col >= 0 && mi_col < cm->mi_cols);
389 bl_index = mi_row * cm->mi_cols + mi_col;
390 // Loop through all 8x8 blocks in superblock and update map.
391 xmis = MIN(cm->mi_cols - mi_col,
392 num_8x8_blocks_wide_lookup[BLOCK_64X64]);
393 ymis = MIN(cm->mi_rows - mi_row,
394 num_8x8_blocks_high_lookup[BLOCK_64X64]);
395 for (y = 0; y < ymis; y++) {
396 for (x = 0; x < xmis; x++) {
397 const int bl_index2 = bl_index + y * cm->mi_cols + x;
398 // If the block is as a candidate for clean up then mark it
399 // for possible boost/refresh (segment 1). The segment id may get
400 // reset to 0 later if block gets coded anything other than ZEROMV.
401 if (cr->map[bl_index2] == 0) {
403 } else if (cr->map[bl_index2] < 0) {
404 cr->map[bl_index2]++;
408 // Enforce constant segment over superblock.
409 // If segment is at least half of superblock, set to 1.
410 if (sum_map >= xmis * ymis / 2) {
411 for (y = 0; y < ymis; y++)
412 for (x = 0; x < xmis; x++) {
413 seg_map[bl_index + y * cm->mi_cols + x] = CR_SEGMENT_ID_BOOST1;
415 cr->target_num_seg_blocks += xmis * ymis;
418 if (i == sbs_in_frame) {
421 } while (cr->target_num_seg_blocks < block_count && i != cr->sb_index);
425 // Set cyclic refresh parameters.
426 void vp9_cyclic_refresh_update_parameters(VP9_COMP *const cpi) {
427 const RATE_CONTROL *const rc = &cpi->rc;
428 const VP9_COMMON *const cm = &cpi->common;
429 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
430 cr->percent_refresh = 10;
431 cr->max_qdelta_perc = 50;
432 cr->time_for_refresh = 0;
433 // Use larger delta-qp (increase rate_ratio_qdelta) for first few (~4)
434 // periods of the refresh cycle, after a key frame.
435 if (rc->frames_since_key < 4 * cr->percent_refresh)
436 cr->rate_ratio_qdelta = 3.0;
438 cr->rate_ratio_qdelta = 2.0;
439 // Adjust some parameters for low resolutions at low bitrates.
440 if (cm->width <= 352 &&
442 rc->avg_frame_bandwidth < 3400) {
443 cr->motion_thresh = 4;
444 cr->rate_boost_fac = 1.25;
446 cr->motion_thresh = 32;
447 cr->rate_boost_fac = 1.7;
451 // Setup cyclic background refresh: set delta q and segmentation map.
452 void vp9_cyclic_refresh_setup(VP9_COMP *const cpi) {
453 VP9_COMMON *const cm = &cpi->common;
454 const RATE_CONTROL *const rc = &cpi->rc;
455 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
456 struct segmentation *const seg = &cm->seg;
457 const int apply_cyclic_refresh = apply_cyclic_refresh_bitrate(cm, rc);
458 if (cm->current_video_frame == 0)
459 cr->low_content_avg = 0.0;
460 // Don't apply refresh on key frame or enhancement layer frames.
461 if (!apply_cyclic_refresh ||
462 (cm->frame_type == KEY_FRAME) ||
463 (cpi->svc.temporal_layer_id > 0) ||
464 (cpi->svc.spatial_layer_id > 0)) {
465 // Set segmentation map to 0 and disable.
466 unsigned char *const seg_map = cpi->segmentation_map;
467 memset(seg_map, 0, cm->mi_rows * cm->mi_cols);
468 vp9_disable_segmentation(&cm->seg);
469 if (cm->frame_type == KEY_FRAME)
473 int qindex_delta = 0;
475 const double q = vp9_convert_qindex_to_q(cm->base_qindex, cm->bit_depth);
476 vp9_clear_system_state();
477 // Set rate threshold to some multiple (set to 2 for now) of the target
478 // rate (target is given by sb64_target_rate and scaled by 256).
479 cr->thresh_rate_sb = ((int64_t)(rc->sb64_target_rate) << 8) << 2;
480 // Distortion threshold, quadratic in Q, scale factor to be adjusted.
481 // q will not exceed 457, so (q * q) is within 32bit; see:
482 // vp9_convert_qindex_to_q(), vp9_ac_quant(), ac_qlookup*[].
483 cr->thresh_dist_sb = ((int64_t)(q * q)) << 2;
485 // Set up segmentation.
486 // Clear down the segment map.
487 vp9_enable_segmentation(&cm->seg);
488 vp9_clearall_segfeatures(seg);
489 // Select delta coding method.
490 seg->abs_delta = SEGMENT_DELTADATA;
492 // Note: setting temporal_update has no effect, as the seg-map coding method
493 // (temporal or spatial) is determined in vp9_choose_segmap_coding_method(),
494 // based on the coding cost of each method. For error_resilient mode on the
495 // last_frame_seg_map is set to 0, so if temporal coding is used, it is
496 // relative to 0 previous map.
497 // seg->temporal_update = 0;
499 // Segment BASE "Q" feature is disabled so it defaults to the baseline Q.
500 vp9_disable_segfeature(seg, CR_SEGMENT_ID_BASE, SEG_LVL_ALT_Q);
501 // Use segment BOOST1 for in-frame Q adjustment.
502 vp9_enable_segfeature(seg, CR_SEGMENT_ID_BOOST1, SEG_LVL_ALT_Q);
503 // Use segment BOOST2 for more aggressive in-frame Q adjustment.
504 vp9_enable_segfeature(seg, CR_SEGMENT_ID_BOOST2, SEG_LVL_ALT_Q);
506 // Set the q delta for segment BOOST1.
507 qindex_delta = compute_deltaq(cpi, cm->base_qindex, cr->rate_ratio_qdelta);
508 cr->qindex_delta_seg1 = qindex_delta;
510 // Compute rd-mult for segment BOOST1.
511 qindex2 = clamp(cm->base_qindex + cm->y_dc_delta_q + qindex_delta, 0, MAXQ);
513 cr->rdmult = vp9_compute_rd_mult(cpi, qindex2);
515 vp9_set_segdata(seg, CR_SEGMENT_ID_BOOST1, SEG_LVL_ALT_Q, qindex_delta);
517 // Set a more aggressive (higher) q delta for segment BOOST2.
518 qindex_delta = compute_deltaq(cpi, cm->base_qindex,
519 MIN(CR_MAX_RATE_TARGET_RATIO,
520 cr->rate_boost_fac * cr->rate_ratio_qdelta));
521 cr->qindex_delta_seg2 = qindex_delta;
522 vp9_set_segdata(seg, CR_SEGMENT_ID_BOOST2, SEG_LVL_ALT_Q, qindex_delta);
524 // Update the segmentation and refresh map.
525 cyclic_refresh_update_map(cpi);
529 int vp9_cyclic_refresh_get_rdmult(const CYCLIC_REFRESH *cr) {
533 void vp9_cyclic_refresh_reset_resize(VP9_COMP *const cpi) {
534 const VP9_COMMON *const cm = &cpi->common;
535 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
536 memset(cr->map, 0, cm->mi_rows * cm->mi_cols);