1 /*
2  *  Copyright (c) 2014 The WebM project authors. All Rights Reserved.
3  *
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.
9  */
10 
11 #include <limits.h>
12 #include <math.h>
13 
14 #include "vpx_dsp/vpx_dsp_common.h"
15 #include "vpx_ports/system_state.h"
16 
17 #include "vp9/encoder/vp9_aq_cyclicrefresh.h"
18 
19 #include "vp9/common/vp9_seg_common.h"
20 
21 #include "vp9/encoder/vp9_ratectrl.h"
22 #include "vp9/encoder/vp9_segmentation.h"
23 
vp9_cyclic_refresh_alloc(int mi_rows,int mi_cols)24 CYCLIC_REFRESH *vp9_cyclic_refresh_alloc(int mi_rows, int mi_cols) {
25   size_t last_coded_q_map_size;
26   size_t consec_zero_mv_size;
27   CYCLIC_REFRESH *const cr = vpx_calloc(1, sizeof(*cr));
28   if (cr == NULL)
29     return NULL;
30 
31   cr->map = vpx_calloc(mi_rows * mi_cols, sizeof(*cr->map));
32   if (cr->map == NULL) {
33     vpx_free(cr);
34     return NULL;
35   }
36   last_coded_q_map_size = mi_rows * mi_cols * sizeof(*cr->last_coded_q_map);
37   cr->last_coded_q_map = vpx_malloc(last_coded_q_map_size);
38   if (cr->last_coded_q_map == NULL) {
39     vpx_free(cr);
40     return NULL;
41   }
42   assert(MAXQ <= 255);
43   memset(cr->last_coded_q_map, MAXQ, last_coded_q_map_size);
44 
45   consec_zero_mv_size = mi_rows * mi_cols * sizeof(*cr->consec_zero_mv);
46   cr->consec_zero_mv = vpx_malloc(consec_zero_mv_size);
47   if (cr->consec_zero_mv == NULL) {
48     vpx_free(cr);
49     return NULL;
50   }
51   memset(cr->consec_zero_mv, 0, consec_zero_mv_size);
52   return cr;
53 }
54 
vp9_cyclic_refresh_free(CYCLIC_REFRESH * cr)55 void vp9_cyclic_refresh_free(CYCLIC_REFRESH *cr) {
56   vpx_free(cr->map);
57   vpx_free(cr->last_coded_q_map);
58   vpx_free(cr->consec_zero_mv);
59   vpx_free(cr);
60 }
61 
62 // Check if we should turn off cyclic refresh based on bitrate condition.
apply_cyclic_refresh_bitrate(const VP9_COMMON * cm,const RATE_CONTROL * rc)63 static int apply_cyclic_refresh_bitrate(const VP9_COMMON *cm,
64                                         const RATE_CONTROL *rc) {
65   // Turn off cyclic refresh if bits available per frame is not sufficiently
66   // larger than bit cost of segmentation. Segment map bit cost should scale
67   // with number of seg blocks, so compare available bits to number of blocks.
68   // Average bits available per frame = avg_frame_bandwidth
69   // Number of (8x8) blocks in frame = mi_rows * mi_cols;
70   const float factor = 0.25;
71   const int number_blocks = cm->mi_rows  * cm->mi_cols;
72   // The condition below corresponds to turning off at target bitrates:
73   // (at 30fps), ~12kbps for CIF, 36kbps for VGA, 100kps for HD/720p.
74   // Also turn off at very small frame sizes, to avoid too large fraction of
75   // superblocks to be refreshed per frame. Threshold below is less than QCIF.
76   if (rc->avg_frame_bandwidth < factor * number_blocks ||
77       number_blocks / 64 < 5)
78     return 0;
79   else
80     return 1;
81 }
82 
83 // Check if this coding block, of size bsize, should be considered for refresh
84 // (lower-qp coding). Decision can be based on various factors, such as
85 // size of the coding block (i.e., below min_block size rejected), coding
86 // mode, and rate/distortion.
candidate_refresh_aq(const CYCLIC_REFRESH * cr,const MB_MODE_INFO * mbmi,int64_t rate,int64_t dist,int bsize)87 static int candidate_refresh_aq(const CYCLIC_REFRESH *cr,
88                                 const MB_MODE_INFO *mbmi,
89                                 int64_t rate,
90                                 int64_t dist,
91                                 int bsize) {
92   MV mv = mbmi->mv[0].as_mv;
93   // Reject the block for lower-qp coding if projected distortion
94   // is above the threshold, and any of the following is true:
95   // 1) mode uses large mv
96   // 2) mode is an intra-mode
97   // Otherwise accept for refresh.
98   if (dist > cr->thresh_dist_sb &&
99       (mv.row > cr->motion_thresh || mv.row < -cr->motion_thresh ||
100        mv.col > cr->motion_thresh || mv.col < -cr->motion_thresh ||
101        !is_inter_block(mbmi)))
102     return CR_SEGMENT_ID_BASE;
103   else  if (bsize >= BLOCK_16X16 &&
104             rate < cr->thresh_rate_sb &&
105             is_inter_block(mbmi) &&
106             mbmi->mv[0].as_int == 0 &&
107             cr->rate_boost_fac > 10)
108     // More aggressive delta-q for bigger blocks with zero motion.
109     return CR_SEGMENT_ID_BOOST2;
110   else
111     return CR_SEGMENT_ID_BOOST1;
112 }
113 
114 // Compute delta-q for the segment.
compute_deltaq(const VP9_COMP * cpi,int q,double rate_factor)115 static int compute_deltaq(const VP9_COMP *cpi, int q, double rate_factor) {
116   const CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
117   const RATE_CONTROL *const rc = &cpi->rc;
118   int deltaq = vp9_compute_qdelta_by_rate(rc, cpi->common.frame_type,
119                                           q, rate_factor,
120                                           cpi->common.bit_depth);
121   if ((-deltaq) > cr->max_qdelta_perc * q / 100) {
122     deltaq = -cr->max_qdelta_perc * q / 100;
123   }
124   return deltaq;
125 }
126 
127 // For the just encoded frame, estimate the bits, incorporating the delta-q
128 // from non-base segment. For now ignore effect of multiple segments
129 // (with different delta-q). Note this function is called in the postencode
130 // (called from rc_update_rate_correction_factors()).
vp9_cyclic_refresh_estimate_bits_at_q(const VP9_COMP * cpi,double correction_factor)131 int vp9_cyclic_refresh_estimate_bits_at_q(const VP9_COMP *cpi,
132                                           double correction_factor) {
133   const VP9_COMMON *const cm = &cpi->common;
134   const CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
135   int estimated_bits;
136   int mbs = cm->MBs;
137   int num8x8bl = mbs << 2;
138   // Weight for non-base segments: use actual number of blocks refreshed in
139   // previous/just encoded frame. Note number of blocks here is in 8x8 units.
140   double weight_segment1 = (double)cr->actual_num_seg1_blocks / num8x8bl;
141   double weight_segment2 = (double)cr->actual_num_seg2_blocks / num8x8bl;
142   // Take segment weighted average for estimated bits.
143   estimated_bits = (int)((1.0 - weight_segment1 - weight_segment2) *
144       vp9_estimate_bits_at_q(cm->frame_type, cm->base_qindex, mbs,
145                              correction_factor, cm->bit_depth) +
146                              weight_segment1 *
147       vp9_estimate_bits_at_q(cm->frame_type,
148                              cm->base_qindex + cr->qindex_delta[1], mbs,
149                              correction_factor, cm->bit_depth) +
150                              weight_segment2 *
151       vp9_estimate_bits_at_q(cm->frame_type,
152                              cm->base_qindex + cr->qindex_delta[2], mbs,
153                              correction_factor, cm->bit_depth));
154   return estimated_bits;
155 }
156 
157 // Prior to encoding the frame, estimate the bits per mb, for a given q = i and
158 // a corresponding delta-q (for segment 1). This function is called in the
159 // rc_regulate_q() to set the base qp index.
160 // Note: the segment map is set to either 0/CR_SEGMENT_ID_BASE (no refresh) or
161 // to 1/CR_SEGMENT_ID_BOOST1 (refresh) for each superblock, prior to encoding.
vp9_cyclic_refresh_rc_bits_per_mb(const VP9_COMP * cpi,int i,double correction_factor)162 int vp9_cyclic_refresh_rc_bits_per_mb(const VP9_COMP *cpi, int i,
163                                       double correction_factor) {
164   const VP9_COMMON *const cm = &cpi->common;
165   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
166   int bits_per_mb;
167   int num8x8bl = cm->MBs << 2;
168   // Weight for segment prior to encoding: take the average of the target
169   // number for the frame to be encoded and the actual from the previous frame.
170   int target_refresh = cr->percent_refresh * cm->mi_rows * cm->mi_cols / 100;
171   double weight_segment = (double)((target_refresh +
172       cr->actual_num_seg1_blocks + cr->actual_num_seg2_blocks) >> 1) /
173       num8x8bl;
174   // Compute delta-q corresponding to qindex i.
175   int deltaq = compute_deltaq(cpi, i, cr->rate_ratio_qdelta);
176   // Take segment weighted average for bits per mb.
177   bits_per_mb = (int)((1.0 - weight_segment) *
178       vp9_rc_bits_per_mb(cm->frame_type, i, correction_factor, cm->bit_depth) +
179       weight_segment *
180       vp9_rc_bits_per_mb(cm->frame_type, i + deltaq, correction_factor,
181                          cm->bit_depth));
182   return bits_per_mb;
183 }
184 
185 // Prior to coding a given prediction block, of size bsize at (mi_row, mi_col),
186 // check if we should reset the segment_id, and update the cyclic_refresh map
187 // and segmentation map.
vp9_cyclic_refresh_update_segment(VP9_COMP * const cpi,MB_MODE_INFO * const mbmi,int mi_row,int mi_col,BLOCK_SIZE bsize,int64_t rate,int64_t dist,int skip)188 void vp9_cyclic_refresh_update_segment(VP9_COMP *const cpi,
189                                        MB_MODE_INFO *const mbmi,
190                                        int mi_row, int mi_col,
191                                        BLOCK_SIZE bsize,
192                                        int64_t rate,
193                                        int64_t dist,
194                                        int skip) {
195   const VP9_COMMON *const cm = &cpi->common;
196   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
197   const int bw = num_8x8_blocks_wide_lookup[bsize];
198   const int bh = num_8x8_blocks_high_lookup[bsize];
199   const int xmis = VPXMIN(cm->mi_cols - mi_col, bw);
200   const int ymis = VPXMIN(cm->mi_rows - mi_row, bh);
201   const int block_index = mi_row * cm->mi_cols + mi_col;
202   const int refresh_this_block = candidate_refresh_aq(cr, mbmi, rate, dist,
203                                                       bsize);
204   // Default is to not update the refresh map.
205   int new_map_value = cr->map[block_index];
206   int x = 0; int y = 0;
207 
208   // If this block is labeled for refresh, check if we should reset the
209   // segment_id.
210   if (cyclic_refresh_segment_id_boosted(mbmi->segment_id)) {
211     mbmi->segment_id = refresh_this_block;
212     // Reset segment_id if it will be skipped.
213     if (skip)
214       mbmi->segment_id = CR_SEGMENT_ID_BASE;
215   }
216 
217   // Update the cyclic refresh map, to be used for setting segmentation map
218   // for the next frame. If the block  will be refreshed this frame, mark it
219   // as clean. The magnitude of the -ve influences how long before we consider
220   // it for refresh again.
221   if (cyclic_refresh_segment_id_boosted(mbmi->segment_id)) {
222     new_map_value = -cr->time_for_refresh;
223   } else if (refresh_this_block) {
224     // Else if it is accepted as candidate for refresh, and has not already
225     // been refreshed (marked as 1) then mark it as a candidate for cleanup
226     // for future time (marked as 0), otherwise don't update it.
227     if (cr->map[block_index] == 1)
228       new_map_value = 0;
229   } else {
230     // Leave it marked as block that is not candidate for refresh.
231     new_map_value = 1;
232   }
233 
234   // Update entries in the cyclic refresh map with new_map_value, and
235   // copy mbmi->segment_id into global segmentation map.
236   for (y = 0; y < ymis; y++)
237     for (x = 0; x < xmis; x++) {
238       int map_offset = block_index + y * cm->mi_cols + x;
239       cr->map[map_offset] = new_map_value;
240       cpi->segmentation_map[map_offset] = mbmi->segment_id;
241     }
242 }
243 
vp9_cyclic_refresh_update_sb_postencode(VP9_COMP * const cpi,const MB_MODE_INFO * const mbmi,int mi_row,int mi_col,BLOCK_SIZE bsize)244 void vp9_cyclic_refresh_update_sb_postencode(VP9_COMP *const cpi,
245                                              const MB_MODE_INFO *const mbmi,
246                                              int mi_row, int mi_col,
247                                              BLOCK_SIZE bsize) {
248   const VP9_COMMON *const cm = &cpi->common;
249   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
250   MV mv = mbmi->mv[0].as_mv;
251   const int bw = num_8x8_blocks_wide_lookup[bsize];
252   const int bh = num_8x8_blocks_high_lookup[bsize];
253   const int xmis = VPXMIN(cm->mi_cols - mi_col, bw);
254   const int ymis = VPXMIN(cm->mi_rows - mi_row, bh);
255   const int block_index = mi_row * cm->mi_cols + mi_col;
256   int x, y;
257   for (y = 0; y < ymis; y++)
258     for (x = 0; x < xmis; x++) {
259       int map_offset = block_index + y * cm->mi_cols + x;
260       // Inter skip blocks were clearly not coded at the current qindex, so
261       // don't update the map for them. For cases where motion is non-zero or
262       // the reference frame isn't the previous frame, the previous value in
263       // the map for this spatial location is not entirely correct.
264       if ((!is_inter_block(mbmi) || !mbmi->skip) &&
265           mbmi->segment_id <= CR_SEGMENT_ID_BOOST2) {
266         cr->last_coded_q_map[map_offset] = clamp(
267             cm->base_qindex + cr->qindex_delta[mbmi->segment_id], 0, MAXQ);
268       } else if (is_inter_block(mbmi) && mbmi->skip &&
269                  mbmi->segment_id <= CR_SEGMENT_ID_BOOST2) {
270         cr->last_coded_q_map[map_offset] = VPXMIN(
271             clamp(cm->base_qindex + cr->qindex_delta[mbmi->segment_id],
272                   0, MAXQ),
273             cr->last_coded_q_map[map_offset]);
274       // Update the consecutive zero/low_mv count.
275       if (is_inter_block(mbmi) && (abs(mv.row) < 8 && abs(mv.col) < 8)) {
276         if (cr->consec_zero_mv[map_offset] < 255)
277           cr->consec_zero_mv[map_offset]++;
278       } else {
279         cr->consec_zero_mv[map_offset] = 0;
280       }
281     }
282   }
283 }
284 
285 // Update the actual number of blocks that were applied the segment delta q.
vp9_cyclic_refresh_postencode(VP9_COMP * const cpi)286 void vp9_cyclic_refresh_postencode(VP9_COMP *const cpi) {
287   VP9_COMMON *const cm = &cpi->common;
288   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
289   unsigned char *const seg_map = cpi->segmentation_map;
290   int mi_row, mi_col;
291   cr->actual_num_seg1_blocks = 0;
292   cr->actual_num_seg2_blocks = 0;
293   for (mi_row = 0; mi_row < cm->mi_rows; mi_row++)
294     for (mi_col = 0; mi_col < cm->mi_cols; mi_col++) {
295       if (cyclic_refresh_segment_id(
296           seg_map[mi_row * cm->mi_cols + mi_col]) == CR_SEGMENT_ID_BOOST1)
297         cr->actual_num_seg1_blocks++;
298       else if (cyclic_refresh_segment_id(
299           seg_map[mi_row * cm->mi_cols + mi_col]) == CR_SEGMENT_ID_BOOST2)
300         cr->actual_num_seg2_blocks++;
301     }
302 }
303 
304 // Set golden frame update interval, for non-svc 1 pass CBR mode.
vp9_cyclic_refresh_set_golden_update(VP9_COMP * const cpi)305 void vp9_cyclic_refresh_set_golden_update(VP9_COMP *const cpi) {
306   RATE_CONTROL *const rc = &cpi->rc;
307   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
308   // Set minimum gf_interval for GF update to a multiple (== 2) of refresh
309   // period. Depending on past encoding stats, GF flag may be reset and update
310   // may not occur until next baseline_gf_interval.
311   if (cr->percent_refresh > 0)
312     rc->baseline_gf_interval = 4 * (100 / cr->percent_refresh);
313   else
314     rc->baseline_gf_interval = 40;
315 }
316 
317 // Update some encoding stats (from the just encoded frame). If this frame's
318 // background has high motion, refresh the golden frame. Otherwise, if the
319 // golden reference is to be updated check if we should NOT update the golden
320 // ref.
vp9_cyclic_refresh_check_golden_update(VP9_COMP * const cpi)321 void vp9_cyclic_refresh_check_golden_update(VP9_COMP *const cpi) {
322   VP9_COMMON *const cm = &cpi->common;
323   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
324   int mi_row, mi_col;
325   double fraction_low = 0.0;
326   int low_content_frame = 0;
327 
328   MODE_INFO **mi = cm->mi_grid_visible;
329   RATE_CONTROL *const rc = &cpi->rc;
330   const int rows = cm->mi_rows, cols = cm->mi_cols;
331   int cnt1 = 0, cnt2 = 0;
332   int force_gf_refresh = 0;
333 
334   for (mi_row = 0; mi_row < rows; mi_row++) {
335     for (mi_col = 0; mi_col < cols; mi_col++) {
336       int16_t abs_mvr = mi[0]->mbmi.mv[0].as_mv.row >= 0 ?
337           mi[0]->mbmi.mv[0].as_mv.row : -1 * mi[0]->mbmi.mv[0].as_mv.row;
338       int16_t abs_mvc = mi[0]->mbmi.mv[0].as_mv.col >= 0 ?
339           mi[0]->mbmi.mv[0].as_mv.col : -1 * mi[0]->mbmi.mv[0].as_mv.col;
340 
341       // Calculate the motion of the background.
342       if (abs_mvr <= 16 && abs_mvc <= 16) {
343         cnt1++;
344         if (abs_mvr == 0 && abs_mvc == 0)
345           cnt2++;
346       }
347       mi++;
348 
349       // Accumulate low_content_frame.
350       if (cr->map[mi_row * cols + mi_col] < 1)
351         low_content_frame++;
352     }
353     mi += 8;
354   }
355 
356   // For video conference clips, if the background has high motion in current
357   // frame because of the camera movement, set this frame as the golden frame.
358   // Use 70% and 5% as the thresholds for golden frame refreshing.
359   // Also, force this frame as a golden update frame if this frame will change
360   // the resolution (resize_pending != 0).
361   if (cpi->resize_pending != 0 ||
362      (cnt1 * 10 > (70 * rows * cols) && cnt2 * 20 < cnt1)) {
363     vp9_cyclic_refresh_set_golden_update(cpi);
364     rc->frames_till_gf_update_due = rc->baseline_gf_interval;
365 
366     if (rc->frames_till_gf_update_due > rc->frames_to_key)
367       rc->frames_till_gf_update_due = rc->frames_to_key;
368     cpi->refresh_golden_frame = 1;
369     force_gf_refresh = 1;
370   }
371 
372   fraction_low =
373       (double)low_content_frame / (rows * cols);
374   // Update average.
375   cr->low_content_avg = (fraction_low + 3 * cr->low_content_avg) / 4;
376   if (!force_gf_refresh && cpi->refresh_golden_frame == 1) {
377     // Don't update golden reference if the amount of low_content for the
378     // current encoded frame is small, or if the recursive average of the
379     // low_content over the update interval window falls below threshold.
380     if (fraction_low < 0.8 || cr->low_content_avg < 0.7)
381       cpi->refresh_golden_frame = 0;
382     // Reset for next internal.
383     cr->low_content_avg = fraction_low;
384   }
385 }
386 
387 // Update the segmentation map, and related quantities: cyclic refresh map,
388 // refresh sb_index, and target number of blocks to be refreshed.
389 // The map is set to either 0/CR_SEGMENT_ID_BASE (no refresh) or to
390 // 1/CR_SEGMENT_ID_BOOST1 (refresh) for each superblock.
391 // Blocks labeled as BOOST1 may later get set to BOOST2 (during the
392 // encoding of the superblock).
cyclic_refresh_update_map(VP9_COMP * const cpi)393 static void cyclic_refresh_update_map(VP9_COMP *const cpi) {
394   VP9_COMMON *const cm = &cpi->common;
395   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
396   unsigned char *const seg_map = cpi->segmentation_map;
397   int i, block_count, bl_index, sb_rows, sb_cols, sbs_in_frame;
398   int xmis, ymis, x, y;
399   int consec_zero_mv_thresh = 0;
400   int qindex_thresh = 0;
401   int count_sel = 0;
402   int count_tot = 0;
403   memset(seg_map, CR_SEGMENT_ID_BASE, cm->mi_rows * cm->mi_cols);
404   sb_cols = (cm->mi_cols + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
405   sb_rows = (cm->mi_rows + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
406   sbs_in_frame = sb_cols * sb_rows;
407   // Number of target blocks to get the q delta (segment 1).
408   block_count = cr->percent_refresh * cm->mi_rows * cm->mi_cols / 100;
409   // Set the segmentation map: cycle through the superblocks, starting at
410   // cr->mb_index, and stopping when either block_count blocks have been found
411   // to be refreshed, or we have passed through whole frame.
412   assert(cr->sb_index < sbs_in_frame);
413   i = cr->sb_index;
414   cr->target_num_seg_blocks = 0;
415   if (cpi->oxcf.content != VP9E_CONTENT_SCREEN)
416     consec_zero_mv_thresh = 100;
417   qindex_thresh =
418       cpi->oxcf.content == VP9E_CONTENT_SCREEN
419       ? vp9_get_qindex(&cm->seg, CR_SEGMENT_ID_BOOST2, cm->base_qindex)
420       : vp9_get_qindex(&cm->seg, CR_SEGMENT_ID_BOOST1, cm->base_qindex);
421   do {
422     int sum_map = 0;
423     // Get the mi_row/mi_col corresponding to superblock index i.
424     int sb_row_index = (i / sb_cols);
425     int sb_col_index = i - sb_row_index * sb_cols;
426     int mi_row = sb_row_index * MI_BLOCK_SIZE;
427     int mi_col = sb_col_index * MI_BLOCK_SIZE;
428     assert(mi_row >= 0 && mi_row < cm->mi_rows);
429     assert(mi_col >= 0 && mi_col < cm->mi_cols);
430     bl_index = mi_row * cm->mi_cols + mi_col;
431     // Loop through all 8x8 blocks in superblock and update map.
432     xmis =
433         VPXMIN(cm->mi_cols - mi_col, num_8x8_blocks_wide_lookup[BLOCK_64X64]);
434     ymis =
435         VPXMIN(cm->mi_rows - mi_row, num_8x8_blocks_high_lookup[BLOCK_64X64]);
436     for (y = 0; y < ymis; y++) {
437       for (x = 0; x < xmis; x++) {
438         const int bl_index2 = bl_index + y * cm->mi_cols + x;
439         // If the block is as a candidate for clean up then mark it
440         // for possible boost/refresh (segment 1). The segment id may get
441         // reset to 0 later if block gets coded anything other than ZEROMV.
442         if (cr->map[bl_index2] == 0) {
443           count_tot++;
444           if (cr->last_coded_q_map[bl_index2] > qindex_thresh ||
445               cr->consec_zero_mv[bl_index2] < consec_zero_mv_thresh) {
446             sum_map++;
447             count_sel++;
448           }
449         } else if (cr->map[bl_index2] < 0) {
450           cr->map[bl_index2]++;
451         }
452       }
453     }
454     // Enforce constant segment over superblock.
455     // If segment is at least half of superblock, set to 1.
456     if (sum_map >= xmis * ymis / 2) {
457       for (y = 0; y < ymis; y++)
458         for (x = 0; x < xmis; x++) {
459           seg_map[bl_index + y * cm->mi_cols + x] = CR_SEGMENT_ID_BOOST1;
460         }
461       cr->target_num_seg_blocks += xmis * ymis;
462     }
463     i++;
464     if (i == sbs_in_frame) {
465       i = 0;
466     }
467   } while (cr->target_num_seg_blocks < block_count && i != cr->sb_index);
468   cr->sb_index = i;
469   cr->reduce_refresh = 0;
470   if (count_sel < (3 * count_tot) >> 2)
471     cr->reduce_refresh = 1;
472 }
473 
474 // Set cyclic refresh parameters.
vp9_cyclic_refresh_update_parameters(VP9_COMP * const cpi)475 void vp9_cyclic_refresh_update_parameters(VP9_COMP *const cpi) {
476   const RATE_CONTROL *const rc = &cpi->rc;
477   const VP9_COMMON *const cm = &cpi->common;
478   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
479   cr->percent_refresh = 10;
480   if (cr->reduce_refresh)
481     cr->percent_refresh = 5;
482   cr->max_qdelta_perc = 50;
483   cr->time_for_refresh = 0;
484   // Use larger delta-qp (increase rate_ratio_qdelta) for first few (~4)
485   // periods of the refresh cycle, after a key frame.
486   // Account for larger interval on base layer for temporal layers.
487   if (cr->percent_refresh > 0 &&
488       rc->frames_since_key <  (4 * cpi->svc.number_temporal_layers) *
489       (100 / cr->percent_refresh))
490     cr->rate_ratio_qdelta = 3.0;
491   else
492     cr->rate_ratio_qdelta = 2.0;
493   // Adjust some parameters for low resolutions at low bitrates.
494   if (cm->width <= 352 &&
495       cm->height <= 288 &&
496       rc->avg_frame_bandwidth < 3400) {
497     cr->motion_thresh = 4;
498     cr->rate_boost_fac = 10;
499   } else {
500     cr->motion_thresh = 32;
501     cr->rate_boost_fac = 15;
502   }
503   if (cpi->svc.spatial_layer_id > 0) {
504     cr->motion_thresh = 4;
505     cr->rate_boost_fac = 12;
506   }
507 }
508 
509 // Setup cyclic background refresh: set delta q and segmentation map.
vp9_cyclic_refresh_setup(VP9_COMP * const cpi)510 void vp9_cyclic_refresh_setup(VP9_COMP *const cpi) {
511   VP9_COMMON *const cm = &cpi->common;
512   const RATE_CONTROL *const rc = &cpi->rc;
513   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
514   struct segmentation *const seg = &cm->seg;
515   const int apply_cyclic_refresh  = apply_cyclic_refresh_bitrate(cm, rc);
516   if (cm->current_video_frame == 0)
517     cr->low_content_avg = 0.0;
518   // Don't apply refresh on key frame or temporal enhancement layer frames.
519   if (!apply_cyclic_refresh ||
520       (cm->frame_type == KEY_FRAME) ||
521       (cpi->svc.temporal_layer_id > 0)) {
522     // Set segmentation map to 0 and disable.
523     unsigned char *const seg_map = cpi->segmentation_map;
524     memset(seg_map, 0, cm->mi_rows * cm->mi_cols);
525     vp9_disable_segmentation(&cm->seg);
526     if (cm->frame_type == KEY_FRAME) {
527       memset(cr->last_coded_q_map, MAXQ,
528              cm->mi_rows * cm->mi_cols * sizeof(*cr->last_coded_q_map));
529       memset(cr->consec_zero_mv, 0,
530              cm->mi_rows * cm->mi_cols * sizeof(*cr->consec_zero_mv));
531       cr->sb_index = 0;
532     }
533     return;
534   } else {
535     int qindex_delta = 0;
536     int qindex2;
537     const double q = vp9_convert_qindex_to_q(cm->base_qindex, cm->bit_depth);
538     vpx_clear_system_state();
539     // Set rate threshold to some multiple (set to 2 for now) of the target
540     // rate (target is given by sb64_target_rate and scaled by 256).
541     cr->thresh_rate_sb = ((int64_t)(rc->sb64_target_rate) << 8) << 2;
542     // Distortion threshold, quadratic in Q, scale factor to be adjusted.
543     // q will not exceed 457, so (q * q) is within 32bit; see:
544     // vp9_convert_qindex_to_q(), vp9_ac_quant(), ac_qlookup*[].
545     cr->thresh_dist_sb = ((int64_t)(q * q)) << 2;
546 
547     // Set up segmentation.
548     // Clear down the segment map.
549     vp9_enable_segmentation(&cm->seg);
550     vp9_clearall_segfeatures(seg);
551     // Select delta coding method.
552     seg->abs_delta = SEGMENT_DELTADATA;
553 
554     // Note: setting temporal_update has no effect, as the seg-map coding method
555     // (temporal or spatial) is determined in vp9_choose_segmap_coding_method(),
556     // based on the coding cost of each method. For error_resilient mode on the
557     // last_frame_seg_map is set to 0, so if temporal coding is used, it is
558     // relative to 0 previous map.
559     // seg->temporal_update = 0;
560 
561     // Segment BASE "Q" feature is disabled so it defaults to the baseline Q.
562     vp9_disable_segfeature(seg, CR_SEGMENT_ID_BASE, SEG_LVL_ALT_Q);
563     // Use segment BOOST1 for in-frame Q adjustment.
564     vp9_enable_segfeature(seg, CR_SEGMENT_ID_BOOST1, SEG_LVL_ALT_Q);
565     // Use segment BOOST2 for more aggressive in-frame Q adjustment.
566     vp9_enable_segfeature(seg, CR_SEGMENT_ID_BOOST2, SEG_LVL_ALT_Q);
567 
568     // Set the q delta for segment BOOST1.
569     qindex_delta = compute_deltaq(cpi, cm->base_qindex, cr->rate_ratio_qdelta);
570     cr->qindex_delta[1] = qindex_delta;
571 
572     // Compute rd-mult for segment BOOST1.
573     qindex2 = clamp(cm->base_qindex + cm->y_dc_delta_q + qindex_delta, 0, MAXQ);
574 
575     cr->rdmult = vp9_compute_rd_mult(cpi, qindex2);
576 
577     vp9_set_segdata(seg, CR_SEGMENT_ID_BOOST1, SEG_LVL_ALT_Q, qindex_delta);
578 
579     // Set a more aggressive (higher) q delta for segment BOOST2.
580     qindex_delta = compute_deltaq(
581         cpi, cm->base_qindex,
582         VPXMIN(CR_MAX_RATE_TARGET_RATIO,
583                0.1 * cr->rate_boost_fac * cr->rate_ratio_qdelta));
584     cr->qindex_delta[2] = qindex_delta;
585     vp9_set_segdata(seg, CR_SEGMENT_ID_BOOST2, SEG_LVL_ALT_Q, qindex_delta);
586 
587     // Reset if resoluton change has occurred.
588     if (cpi->resize_pending != 0)
589       vp9_cyclic_refresh_reset_resize(cpi);
590 
591     // Update the segmentation and refresh map.
592     cyclic_refresh_update_map(cpi);
593   }
594 }
595 
vp9_cyclic_refresh_get_rdmult(const CYCLIC_REFRESH * cr)596 int vp9_cyclic_refresh_get_rdmult(const CYCLIC_REFRESH *cr) {
597   return cr->rdmult;
598 }
599 
vp9_cyclic_refresh_reset_resize(VP9_COMP * const cpi)600 void vp9_cyclic_refresh_reset_resize(VP9_COMP *const cpi) {
601   const VP9_COMMON *const cm = &cpi->common;
602   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
603   memset(cr->map, 0, cm->mi_rows * cm->mi_cols);
604   memset(cr->last_coded_q_map, MAXQ, cm->mi_rows * cm->mi_cols);
605   memset(cr->consec_zero_mv, 0, cm->mi_rows * cm->mi_cols);
606   cr->sb_index = 0;
607   cpi->refresh_golden_frame = 1;
608 }
609