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 "vp9/encoder/vp9_aq_cyclicrefresh.h" 15 16#include "vp9/common/vp9_seg_common.h" 17 18#include "vp9/encoder/vp9_ratectrl.h" 19#include "vp9/encoder/vp9_rdopt.h" 20#include "vp9/encoder/vp9_segmentation.h" 21 22struct CYCLIC_REFRESH { 23 // Percentage of super-blocks per frame that are targeted as candidates 24 // for cyclic refresh. 25 int max_sbs_perframe; 26 // Maximum q-delta as percentage of base q. 27 int max_qdelta_perc; 28 // Block size below which we don't apply cyclic refresh. 29 BLOCK_SIZE min_block_size; 30 // Superblock starting index for cycling through the frame. 31 int sb_index; 32 // Controls how long a block will need to wait to be refreshed again. 33 int time_for_refresh; 34 // Actual number of (8x8) blocks that were applied delta-q (segment 1). 35 int num_seg_blocks; 36 // Actual encoding bits for segment 1. 37 int actual_seg_bits; 38 // RD mult. parameters for segment 1. 39 int rdmult; 40 // Cyclic refresh map. 41 signed char *map; 42 // Projected rate and distortion for the current superblock. 43 int64_t projected_rate_sb; 44 int64_t projected_dist_sb; 45 // Thresholds applied to projected rate/distortion of the superblock. 46 int64_t thresh_rate_sb; 47 int64_t thresh_dist_sb; 48}; 49 50CYCLIC_REFRESH *vp9_cyclic_refresh_alloc(int mi_rows, int mi_cols) { 51 CYCLIC_REFRESH *const cr = vpx_calloc(1, sizeof(*cr)); 52 if (cr == NULL) 53 return NULL; 54 55 cr->map = vpx_calloc(mi_rows * mi_cols, sizeof(*cr->map)); 56 if (cr->map == NULL) { 57 vpx_free(cr); 58 return NULL; 59 } 60 61 return cr; 62} 63 64void vp9_cyclic_refresh_free(CYCLIC_REFRESH *cr) { 65 vpx_free(cr->map); 66 vpx_free(cr); 67} 68 69// Check if we should turn off cyclic refresh based on bitrate condition. 70static 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 = av_per_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->av_per_frame_bandwidth < factor * number_blocks || 84 number_blocks / 64 < 5) 85 return 0; 86 else 87 return 1; 88} 89 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. 94static int candidate_refresh_aq(const CYCLIC_REFRESH *cr, 95 const MB_MODE_INFO *mbmi, 96 BLOCK_SIZE bsize, int use_rd) { 97 if (use_rd) { 98 // If projected rate is below the thresh_rate (well below target, 99 // so undershoot expected), accept it for lower-qp coding. 100 if (cr->projected_rate_sb < cr->thresh_rate_sb) 101 return 1; 102 // Otherwise, reject the block for lower-qp coding if any of the following: 103 // 1) prediction block size is below min_block_size 104 // 2) mode is non-zero mv and projected distortion is above thresh_dist 105 // 3) mode is an intra-mode (we may want to allow some of this under 106 // another thresh_dist) 107 else if (bsize < cr->min_block_size || 108 (mbmi->mv[0].as_int != 0 && 109 cr->projected_dist_sb > cr->thresh_dist_sb) || 110 !is_inter_block(mbmi)) 111 return 0; 112 else 113 return 1; 114 } else { 115 // Rate/distortion not used for update. 116 if (bsize < cr->min_block_size || 117 mbmi->mv[0].as_int != 0 || 118 !is_inter_block(mbmi)) 119 return 0; 120 else 121 return 1; 122 } 123} 124 125// Prior to coding a given prediction block, of size bsize at (mi_row, mi_col), 126// check if we should reset the segment_id, and update the cyclic_refresh map 127// and segmentation map. 128void vp9_cyclic_refresh_update_segment(VP9_COMP *const cpi, 129 MB_MODE_INFO *const mbmi, 130 int mi_row, int mi_col, 131 BLOCK_SIZE bsize, int use_rd) { 132 const VP9_COMMON *const cm = &cpi->common; 133 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; 134 const int bw = num_8x8_blocks_wide_lookup[bsize]; 135 const int bh = num_8x8_blocks_high_lookup[bsize]; 136 const int xmis = MIN(cm->mi_cols - mi_col, bw); 137 const int ymis = MIN(cm->mi_rows - mi_row, bh); 138 const int block_index = mi_row * cm->mi_cols + mi_col; 139 const int refresh_this_block = candidate_refresh_aq(cr, mbmi, bsize, use_rd); 140 // Default is to not update the refresh map. 141 int new_map_value = cr->map[block_index]; 142 int x = 0; int y = 0; 143 144 // Check if we should reset the segment_id for this block. 145 if (mbmi->segment_id > 0 && !refresh_this_block) 146 mbmi->segment_id = 0; 147 148 // Update the cyclic refresh map, to be used for setting segmentation map 149 // for the next frame. If the block will be refreshed this frame, mark it 150 // as clean. The magnitude of the -ve influences how long before we consider 151 // it for refresh again. 152 if (mbmi->segment_id == 1) { 153 new_map_value = -cr->time_for_refresh; 154 } else if (refresh_this_block) { 155 // Else if it is accepted as candidate for refresh, and has not already 156 // been refreshed (marked as 1) then mark it as a candidate for cleanup 157 // for future time (marked as 0), otherwise don't update it. 158 if (cr->map[block_index] == 1) 159 new_map_value = 0; 160 } else { 161 // Leave it marked as block that is not candidate for refresh. 162 new_map_value = 1; 163 } 164 // Update entries in the cyclic refresh map with new_map_value, and 165 // copy mbmi->segment_id into global segmentation map. 166 for (y = 0; y < ymis; y++) 167 for (x = 0; x < xmis; x++) { 168 cr->map[block_index + y * cm->mi_cols + x] = new_map_value; 169 cpi->segmentation_map[block_index + y * cm->mi_cols + x] = 170 mbmi->segment_id; 171 } 172 // Keep track of actual number (in units of 8x8) of blocks in segment 1 used 173 // for encoding this frame. 174 if (mbmi->segment_id) 175 cr->num_seg_blocks += xmis * ymis; 176} 177 178// Setup cyclic background refresh: set delta q and segmentation map. 179void vp9_cyclic_refresh_setup(VP9_COMP *const cpi) { 180 VP9_COMMON *const cm = &cpi->common; 181 const RATE_CONTROL *const rc = &cpi->rc; 182 CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; 183 struct segmentation *const seg = &cm->seg; 184 unsigned char *const seg_map = cpi->segmentation_map; 185 const int apply_cyclic_refresh = apply_cyclic_refresh_bitrate(cm, rc); 186 // Don't apply refresh on key frame or enhancement layer frames. 187 if (!apply_cyclic_refresh || 188 (cm->frame_type == KEY_FRAME) || 189 (cpi->svc.temporal_layer_id > 0)) { 190 // Set segmentation map to 0 and disable. 191 vpx_memset(seg_map, 0, cm->mi_rows * cm->mi_cols); 192 vp9_disable_segmentation(&cm->seg); 193 if (cm->frame_type == KEY_FRAME) 194 cr->sb_index = 0; 195 return; 196 } else { 197 int qindex_delta = 0; 198 int i, block_count, bl_index, sb_rows, sb_cols, sbs_in_frame; 199 int xmis, ymis, x, y, qindex2; 200 201 // Rate target ratio to set q delta. 202 const float rate_ratio_qdelta = 2.0; 203 vp9_clear_system_state(); 204 // Some of these parameters may be set via codec-control function later. 205 cr->max_sbs_perframe = 10; 206 cr->max_qdelta_perc = 50; 207 cr->min_block_size = BLOCK_8X8; 208 cr->time_for_refresh = 1; 209 // Set rate threshold to some fraction of target (and scaled by 256). 210 cr->thresh_rate_sb = (rc->sb64_target_rate * 256) >> 2; 211 // Distortion threshold, quadratic in Q, scale factor to be adjusted. 212 cr->thresh_dist_sb = 8 * (int)(vp9_convert_qindex_to_q(cm->base_qindex) * 213 vp9_convert_qindex_to_q(cm->base_qindex)); 214 if (cpi->sf.use_nonrd_pick_mode) { 215 // May want to be more conservative with thresholds in non-rd mode for now 216 // as rate/distortion are derived from model based on prediction residual. 217 cr->thresh_rate_sb = (rc->sb64_target_rate * 256) >> 3; 218 cr->thresh_dist_sb = 4 * (int)(vp9_convert_qindex_to_q(cm->base_qindex) * 219 vp9_convert_qindex_to_q(cm->base_qindex)); 220 } 221 222 cr->num_seg_blocks = 0; 223 // Set up segmentation. 224 // Clear down the segment map. 225 vpx_memset(seg_map, 0, cm->mi_rows * cm->mi_cols); 226 vp9_enable_segmentation(&cm->seg); 227 vp9_clearall_segfeatures(seg); 228 // Select delta coding method. 229 seg->abs_delta = SEGMENT_DELTADATA; 230 231 // Note: setting temporal_update has no effect, as the seg-map coding method 232 // (temporal or spatial) is determined in vp9_choose_segmap_coding_method(), 233 // based on the coding cost of each method. For error_resilient mode on the 234 // last_frame_seg_map is set to 0, so if temporal coding is used, it is 235 // relative to 0 previous map. 236 // seg->temporal_update = 0; 237 238 // Segment 0 "Q" feature is disabled so it defaults to the baseline Q. 239 vp9_disable_segfeature(seg, 0, SEG_LVL_ALT_Q); 240 // Use segment 1 for in-frame Q adjustment. 241 vp9_enable_segfeature(seg, 1, SEG_LVL_ALT_Q); 242 243 // Set the q delta for segment 1. 244 qindex_delta = vp9_compute_qdelta_by_rate(cpi, 245 cm->base_qindex, 246 rate_ratio_qdelta); 247 // TODO(marpan): Incorporate the actual-vs-target rate over/undershoot from 248 // previous encoded frame. 249 if (-qindex_delta > cr->max_qdelta_perc * cm->base_qindex / 100) 250 qindex_delta = -cr->max_qdelta_perc * cm->base_qindex / 100; 251 252 // Compute rd-mult for segment 1. 253 qindex2 = clamp(cm->base_qindex + cm->y_dc_delta_q + qindex_delta, 0, MAXQ); 254 cr->rdmult = vp9_compute_rd_mult(cpi, qindex2); 255 256 vp9_set_segdata(seg, 1, SEG_LVL_ALT_Q, qindex_delta); 257 258 sb_cols = (cm->mi_cols + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE; 259 sb_rows = (cm->mi_rows + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE; 260 sbs_in_frame = sb_cols * sb_rows; 261 // Number of target superblocks to get the q delta (segment 1). 262 block_count = cr->max_sbs_perframe * sbs_in_frame / 100; 263 // Set the segmentation map: cycle through the superblocks, starting at 264 // cr->mb_index, and stopping when either block_count blocks have been found 265 // to be refreshed, or we have passed through whole frame. 266 assert(cr->sb_index < sbs_in_frame); 267 i = cr->sb_index; 268 do { 269 int sum_map = 0; 270 // Get the mi_row/mi_col corresponding to superblock index i. 271 int sb_row_index = (i / sb_cols); 272 int sb_col_index = i - sb_row_index * sb_cols; 273 int mi_row = sb_row_index * MI_BLOCK_SIZE; 274 int mi_col = sb_col_index * MI_BLOCK_SIZE; 275 assert(mi_row >= 0 && mi_row < cm->mi_rows); 276 assert(mi_col >= 0 && mi_col < cm->mi_cols); 277 bl_index = mi_row * cm->mi_cols + mi_col; 278 // Loop through all 8x8 blocks in superblock and update map. 279 xmis = MIN(cm->mi_cols - mi_col, 280 num_8x8_blocks_wide_lookup[BLOCK_64X64]); 281 ymis = MIN(cm->mi_rows - mi_row, 282 num_8x8_blocks_high_lookup[BLOCK_64X64]); 283 for (y = 0; y < ymis; y++) { 284 for (x = 0; x < xmis; x++) { 285 const int bl_index2 = bl_index + y * cm->mi_cols + x; 286 // If the block is as a candidate for clean up then mark it 287 // for possible boost/refresh (segment 1). The segment id may get 288 // reset to 0 later if block gets coded anything other than ZEROMV. 289 if (cr->map[bl_index2] == 0) { 290 seg_map[bl_index2] = 1; 291 sum_map++; 292 } else if (cr->map[bl_index2] < 0) { 293 cr->map[bl_index2]++; 294 } 295 } 296 } 297 // Enforce constant segment over superblock. 298 // If segment is partial over superblock, reset to either all 1 or 0. 299 if (sum_map > 0 && sum_map < xmis * ymis) { 300 const int new_value = (sum_map >= xmis * ymis / 2); 301 for (y = 0; y < ymis; y++) 302 for (x = 0; x < xmis; x++) 303 seg_map[bl_index + y * cm->mi_cols + x] = new_value; 304 } 305 i++; 306 if (i == sbs_in_frame) { 307 i = 0; 308 } 309 if (sum_map >= xmis * ymis /2) 310 block_count--; 311 } while (block_count && i != cr->sb_index); 312 cr->sb_index = i; 313 } 314} 315 316void vp9_cyclic_refresh_set_rate_and_dist_sb(CYCLIC_REFRESH *cr, 317 int64_t rate_sb, int64_t dist_sb) { 318 cr->projected_rate_sb = rate_sb; 319 cr->projected_dist_sb = dist_sb; 320} 321 322int vp9_cyclic_refresh_get_rdmult(const CYCLIC_REFRESH *cr) { 323 return cr->rdmult; 324} 325