ref: e18800443cf76853103e6419bb3b86bf52feec15
dir: /vp10/encoder/aq_cyclicrefresh.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 "vp10/common/seg_common.h" #include "vp10/encoder/aq_cyclicrefresh.h" #include "vp10/encoder/ratectrl.h" #include "vp10/encoder/segmentation.h" #include "vpx_ports/system_state.h" struct CYCLIC_REFRESH { // Percentage of blocks per frame that are targeted as candidates // for cyclic refresh. int percent_refresh; // Maximum q-delta as percentage of base q. int max_qdelta_perc; // Superblock starting index for cycling through the frame. int sb_index; // Controls how long block will need to wait to be refreshed again, in // excess of the cycle time, i.e., in the case of all zero motion, block // will be refreshed every (100/percent_refresh + time_for_refresh) frames. int time_for_refresh; // Target number of (8x8) blocks that are set for delta-q. int target_num_seg_blocks; // Actual number of (8x8) blocks that were applied delta-q. int actual_num_seg1_blocks; int actual_num_seg2_blocks; // RD mult. parameters for segment 1. int rdmult; // Cyclic refresh map. signed char *map; // Map of the last q a block was coded at. uint8_t *last_coded_q_map; // Thresholds applied to the projected rate/distortion of the coding block, // when deciding whether block should be refreshed. int64_t thresh_rate_sb; int64_t thresh_dist_sb; // Threshold applied to the motion vector (in units of 1/8 pel) of the // coding block, when deciding whether block should be refreshed. int16_t motion_thresh; // Rate target ratio to set q delta. double rate_ratio_qdelta; // Boost factor for rate target ratio, for segment CR_SEGMENT_ID_BOOST2. int rate_boost_fac; double low_content_avg; int qindex_delta[3]; }; CYCLIC_REFRESH *vp10_cyclic_refresh_alloc(int mi_rows, int mi_cols) { size_t last_coded_q_map_size; CYCLIC_REFRESH *const cr = vpx_calloc(1, sizeof(*cr)); if (cr == NULL) return NULL; cr->map = vpx_calloc(mi_rows * mi_cols, sizeof(*cr->map)); if (cr->map == NULL) { vpx_free(cr); return NULL; } last_coded_q_map_size = mi_rows * mi_cols * sizeof(*cr->last_coded_q_map); cr->last_coded_q_map = vpx_malloc(last_coded_q_map_size); if (cr->last_coded_q_map == NULL) { vpx_free(cr); return NULL; } assert(MAXQ <= 255); memset(cr->last_coded_q_map, MAXQ, last_coded_q_map_size); return cr; } void vp10_cyclic_refresh_free(CYCLIC_REFRESH *cr) { vpx_free(cr->map); vpx_free(cr->last_coded_q_map); vpx_free(cr); } // Check if we should turn off cyclic refresh based on bitrate condition. static int apply_cyclic_refresh_bitrate(const VP10_COMMON *cm, const RATE_CONTROL *rc) { // 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 = avg_frame_bandwidth // Number of (8x8) blocks in frame = mi_rows * mi_cols; const float factor = 0.25; const int number_blocks = cm->mi_rows * cm->mi_cols; // The condition below corresponds to turning off at target bitrates: // (at 30fps), ~12kbps for CIF, 36kbps for VGA, 100kps for HD/720p. // Also turn off at very small frame sizes, to avoid too large fraction of // superblocks to be refreshed per frame. Threshold below is less than QCIF. if (rc->avg_frame_bandwidth < factor * number_blocks || number_blocks / 64 < 5) 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(const CYCLIC_REFRESH *cr, const MB_MODE_INFO *mbmi, int64_t rate, int64_t dist, int bsize) { MV mv = mbmi->mv[0].as_mv; // Reject the block for lower-qp coding if projected distortion // is above the threshold, and any of the following is true: // 1) mode uses large mv // 2) mode is an intra-mode // Otherwise accept for refresh. if (dist > cr->thresh_dist_sb && (mv.row > cr->motion_thresh || mv.row < -cr->motion_thresh || mv.col > cr->motion_thresh || mv.col < -cr->motion_thresh || !is_inter_block(mbmi))) return CR_SEGMENT_ID_BASE; else if (bsize >= BLOCK_16X16 && rate < cr->thresh_rate_sb && is_inter_block(mbmi) && mbmi->mv[0].as_int == 0 && cr->rate_boost_fac > 10) // More aggressive delta-q for bigger blocks with zero motion. return CR_SEGMENT_ID_BOOST2; else return CR_SEGMENT_ID_BOOST1; } // Compute delta-q for the segment. static int compute_deltaq(const VP10_COMP *cpi, int q, double rate_factor) { const CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; const RATE_CONTROL *const rc = &cpi->rc; int deltaq = vp10_compute_qdelta_by_rate(rc, cpi->common.frame_type, q, rate_factor, cpi->common.bit_depth); if ((-deltaq) > cr->max_qdelta_perc * q / 100) { deltaq = -cr->max_qdelta_perc * q / 100; } return deltaq; } // For the just encoded frame, estimate the bits, incorporating the delta-q // from non-base segment. For now ignore effect of multiple segments // (with different delta-q). Note this function is called in the postencode // (called from rc_update_rate_correction_factors()). int vp10_cyclic_refresh_estimate_bits_at_q(const VP10_COMP *cpi, double correction_factor) { const VP10_COMMON *const cm = &cpi->common; const CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; int estimated_bits; int mbs = cm->MBs; int num8x8bl = mbs << 2; // Weight for non-base segments: use actual number of blocks refreshed in // previous/just encoded frame. Note number of blocks here is in 8x8 units. double weight_segment1 = (double)cr->actual_num_seg1_blocks / num8x8bl; double weight_segment2 = (double)cr->actual_num_seg2_blocks / num8x8bl; // Take segment weighted average for estimated bits. estimated_bits = (int)((1.0 - weight_segment1 - weight_segment2) * vp10_estimate_bits_at_q(cm->frame_type, cm->base_qindex, mbs, correction_factor, cm->bit_depth) + weight_segment1 * vp10_estimate_bits_at_q(cm->frame_type, cm->base_qindex + cr->qindex_delta[1], mbs, correction_factor, cm->bit_depth) + weight_segment2 * vp10_estimate_bits_at_q(cm->frame_type, cm->base_qindex + cr->qindex_delta[2], mbs, correction_factor, cm->bit_depth)); return estimated_bits; } // Prior to encoding the frame, estimate the bits per mb, for a given q = i and // a corresponding delta-q (for segment 1). This function is called in the // rc_regulate_q() to set the base qp index. // Note: the segment map is set to either 0/CR_SEGMENT_ID_BASE (no refresh) or // to 1/CR_SEGMENT_ID_BOOST1 (refresh) for each superblock, prior to encoding. int vp10_cyclic_refresh_rc_bits_per_mb(const VP10_COMP *cpi, int i, double correction_factor) { const VP10_COMMON *const cm = &cpi->common; CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; int bits_per_mb; int num8x8bl = cm->MBs << 2; // Weight for segment prior to encoding: take the average of the target // number for the frame to be encoded and the actual from the previous frame. double weight_segment = (double)((cr->target_num_seg_blocks + cr->actual_num_seg1_blocks + cr->actual_num_seg2_blocks) >> 1) / num8x8bl; // Compute delta-q corresponding to qindex i. int deltaq = compute_deltaq(cpi, i, cr->rate_ratio_qdelta); // Take segment weighted average for bits per mb. bits_per_mb = (int)((1.0 - weight_segment) * vp10_rc_bits_per_mb(cm->frame_type, i, correction_factor, cm->bit_depth) + weight_segment * vp10_rc_bits_per_mb(cm->frame_type, i + deltaq, correction_factor, cm->bit_depth)); return bits_per_mb; } // 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 vp10_cyclic_refresh_update_segment(VP10_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) { const VP10_COMMON *const cm = &cpi->common; CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; 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; const int refresh_this_block = candidate_refresh_aq(cr, mbmi, rate, dist, bsize); // Default is to not update the refresh map. int new_map_value = cr->map[block_index]; int x = 0; int y = 0; // If this block is labeled for refresh, check if we should reset the // segment_id. if (cyclic_refresh_segment_id_boosted(mbmi->segment_id)) { mbmi->segment_id = refresh_this_block; // Reset segment_id if will be skipped. if (skip) mbmi->segment_id = CR_SEGMENT_ID_BASE; } // 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 (cyclic_refresh_segment_id_boosted(mbmi->segment_id)) { 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++) { int map_offset = block_index + y * cm->mi_cols + x; cr->map[map_offset] = new_map_value; cpi->segmentation_map[map_offset] = mbmi->segment_id; // Inter skip blocks were clearly not coded at the current qindex, so // don't update the map for them. For cases where motion is non-zero or // the reference frame isn't the previous frame, the previous value in // the map for this spatial location is not entirely correct. if (!is_inter_block(mbmi) || !skip) cr->last_coded_q_map[map_offset] = clamp( cm->base_qindex + cr->qindex_delta[mbmi->segment_id], 0, MAXQ); } } // Update the actual number of blocks that were applied the segment delta q. void vp10_cyclic_refresh_postencode(VP10_COMP *const cpi) { VP10_COMMON *const cm = &cpi->common; CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; unsigned char *const seg_map = cpi->segmentation_map; int mi_row, mi_col; cr->actual_num_seg1_blocks = 0; cr->actual_num_seg2_blocks = 0; for (mi_row = 0; mi_row < cm->mi_rows; mi_row++) for (mi_col = 0; mi_col < cm->mi_cols; mi_col++) { if (cyclic_refresh_segment_id( seg_map[mi_row * cm->mi_cols + mi_col]) == CR_SEGMENT_ID_BOOST1) cr->actual_num_seg1_blocks++; else if (cyclic_refresh_segment_id( seg_map[mi_row * cm->mi_cols + mi_col]) == CR_SEGMENT_ID_BOOST2) cr->actual_num_seg2_blocks++; } } // Set golden frame update interval, for non-svc 1 pass CBR mode. void vp10_cyclic_refresh_set_golden_update(VP10_COMP *const cpi) { RATE_CONTROL *const rc = &cpi->rc; CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; // Set minimum gf_interval for GF update to a multiple (== 2) of refresh // period. Depending on past encoding stats, GF flag may be reset and update // may not occur until next baseline_gf_interval. if (cr->percent_refresh > 0) rc->baseline_gf_interval = 4 * (100 / cr->percent_refresh); else rc->baseline_gf_interval = 40; } // Update some encoding stats (from the just encoded frame). If this frame's // background has high motion, refresh the golden frame. Otherwise, if the // golden reference is to be updated check if we should NOT update the golden // ref. void vp10_cyclic_refresh_check_golden_update(VP10_COMP *const cpi) { VP10_COMMON *const cm = &cpi->common; CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; int mi_row, mi_col; double fraction_low = 0.0; int low_content_frame = 0; MODE_INFO **mi = cm->mi_grid_visible; RATE_CONTROL *const rc = &cpi->rc; const int rows = cm->mi_rows, cols = cm->mi_cols; int cnt1 = 0, cnt2 = 0; int force_gf_refresh = 0; for (mi_row = 0; mi_row < rows; mi_row++) { for (mi_col = 0; mi_col < cols; mi_col++) { int16_t abs_mvr = mi[0]->mbmi.mv[0].as_mv.row >= 0 ? mi[0]->mbmi.mv[0].as_mv.row : -1 * mi[0]->mbmi.mv[0].as_mv.row; int16_t abs_mvc = mi[0]->mbmi.mv[0].as_mv.col >= 0 ? mi[0]->mbmi.mv[0].as_mv.col : -1 * mi[0]->mbmi.mv[0].as_mv.col; // Calculate the motion of the background. if (abs_mvr <= 16 && abs_mvc <= 16) { cnt1++; if (abs_mvr == 0 && abs_mvc == 0) cnt2++; } mi++; // Accumulate low_content_frame. if (cr->map[mi_row * cols + mi_col] < 1) low_content_frame++; } mi += 8; } // For video conference clips, if the background has high motion in current // frame because of the camera movement, set this frame as the golden frame. // Use 70% and 5% as the thresholds for golden frame refreshing. // Also, force this frame as a golden update frame if this frame will change // the resolution (resize_pending != 0). if (cpi->resize_pending != 0 || (cnt1 * 10 > (70 * rows * cols) && cnt2 * 20 < cnt1)) { vp10_cyclic_refresh_set_golden_update(cpi); rc->frames_till_gf_update_due = rc->baseline_gf_interval; if (rc->frames_till_gf_update_due > rc->frames_to_key) rc->frames_till_gf_update_due = rc->frames_to_key; cpi->refresh_golden_frame = 1; force_gf_refresh = 1; } fraction_low = (double)low_content_frame / (rows * cols); // Update average. cr->low_content_avg = (fraction_low + 3 * cr->low_content_avg) / 4; if (!force_gf_refresh && cpi->refresh_golden_frame == 1) { // Don't update golden reference if the amount of low_content for the // current encoded frame is small, or if the recursive average of the // low_content over the update interval window falls below threshold. if (fraction_low < 0.8 || cr->low_content_avg < 0.7) cpi->refresh_golden_frame = 0; // Reset for next internal. cr->low_content_avg = fraction_low; } } // Update the segmentation map, and related quantities: cyclic refresh map, // refresh sb_index, and target number of blocks to be refreshed. // The map is set to either 0/CR_SEGMENT_ID_BASE (no refresh) or to // 1/CR_SEGMENT_ID_BOOST1 (refresh) for each superblock. // Blocks labeled as BOOST1 may later get set to BOOST2 (during the // encoding of the superblock). static void cyclic_refresh_update_map(VP10_COMP *const cpi) { VP10_COMMON *const cm = &cpi->common; CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; unsigned char *const seg_map = cpi->segmentation_map; int i, block_count, bl_index, sb_rows, sb_cols, sbs_in_frame; int xmis, ymis, x, y; memset(seg_map, CR_SEGMENT_ID_BASE, cm->mi_rows * cm->mi_cols); sb_cols = (cm->mi_cols + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE; sb_rows = (cm->mi_rows + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE; sbs_in_frame = sb_cols * sb_rows; // Number of target blocks to get the q delta (segment 1). block_count = cr->percent_refresh * cm->mi_rows * cm->mi_cols / 100; // Set the segmentation map: cycle through the superblocks, 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. assert(cr->sb_index < sbs_in_frame); i = cr->sb_index; cr->target_num_seg_blocks = 0; do { int sum_map = 0; // Get the mi_row/mi_col corresponding to superblock index i. int sb_row_index = (i / sb_cols); int sb_col_index = i - sb_row_index * sb_cols; int mi_row = sb_row_index * MI_BLOCK_SIZE; int mi_col = sb_col_index * MI_BLOCK_SIZE; int qindex_thresh = cpi->oxcf.content == VP9E_CONTENT_SCREEN ? vp10_get_qindex(&cm->seg, CR_SEGMENT_ID_BOOST2, cm->base_qindex) : 0; assert(mi_row >= 0 && mi_row < cm->mi_rows); assert(mi_col >= 0 && mi_col < cm->mi_cols); bl_index = mi_row * cm->mi_cols + mi_col; // Loop through all 8x8 blocks in superblock and update map. xmis = MIN(cm->mi_cols - mi_col, num_8x8_blocks_wide_lookup[BLOCK_64X64]); ymis = MIN(cm->mi_rows - mi_row, num_8x8_blocks_high_lookup[BLOCK_64X64]); for (y = 0; y < ymis; y++) { for (x = 0; x < xmis; x++) { const int bl_index2 = bl_index + y * cm->mi_cols + x; // If the block 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 block gets coded anything other than ZEROMV. if (cr->map[bl_index2] == 0) { if (cr->last_coded_q_map[bl_index2] > qindex_thresh) sum_map++; } else if (cr->map[bl_index2] < 0) { cr->map[bl_index2]++; } } } // Enforce constant segment over superblock. // If segment is at least half of superblock, set to 1. if (sum_map >= xmis * ymis / 2) { for (y = 0; y < ymis; y++) for (x = 0; x < xmis; x++) { seg_map[bl_index + y * cm->mi_cols + x] = CR_SEGMENT_ID_BOOST1; } cr->target_num_seg_blocks += xmis * ymis; } i++; if (i == sbs_in_frame) { i = 0; } } while (cr->target_num_seg_blocks < block_count && i != cr->sb_index); cr->sb_index = i; } // Set cyclic refresh parameters. void vp10_cyclic_refresh_update_parameters(VP10_COMP *const cpi) { const RATE_CONTROL *const rc = &cpi->rc; const VP10_COMMON *const cm = &cpi->common; CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; cr->percent_refresh = 10; cr->max_qdelta_perc = 50; cr->time_for_refresh = 0; // Use larger delta-qp (increase rate_ratio_qdelta) for first few (~4) // periods of the refresh cycle, after a key frame. if (rc->frames_since_key < 4 * cr->percent_refresh) cr->rate_ratio_qdelta = 3.0; else cr->rate_ratio_qdelta = 2.0; // Adjust some parameters for low resolutions at low bitrates. if (cm->width <= 352 && cm->height <= 288 && rc->avg_frame_bandwidth < 3400) { cr->motion_thresh = 4; cr->rate_boost_fac = 10; } else { cr->motion_thresh = 32; cr->rate_boost_fac = 17; } } // Setup cyclic background refresh: set delta q and segmentation map. void vp10_cyclic_refresh_setup(VP10_COMP *const cpi) { VP10_COMMON *const cm = &cpi->common; const RATE_CONTROL *const rc = &cpi->rc; CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; struct segmentation *const seg = &cm->seg; const int apply_cyclic_refresh = apply_cyclic_refresh_bitrate(cm, rc); if (cm->current_video_frame == 0) cr->low_content_avg = 0.0; // Don't apply refresh on key frame or enhancement layer frames. if (!apply_cyclic_refresh || (cm->frame_type == KEY_FRAME) || (cpi->svc.temporal_layer_id > 0) || (cpi->svc.spatial_layer_id > 0)) { // Set segmentation map to 0 and disable. unsigned char *const seg_map = cpi->segmentation_map; memset(seg_map, 0, cm->mi_rows * cm->mi_cols); vp10_disable_segmentation(&cm->seg); if (cm->frame_type == KEY_FRAME) { memset(cr->last_coded_q_map, MAXQ, cm->mi_rows * cm->mi_cols * sizeof(*cr->last_coded_q_map)); cr->sb_index = 0; } return; } else { int qindex_delta = 0; int qindex2; const double q = vp10_convert_qindex_to_q(cm->base_qindex, cm->bit_depth); vpx_clear_system_state(); // Set rate threshold to some multiple (set to 2 for now) of the target // rate (target is given by sb64_target_rate and scaled by 256). cr->thresh_rate_sb = ((int64_t)(rc->sb64_target_rate) << 8) << 2; // Distortion threshold, quadratic in Q, scale factor to be adjusted. // q will not exceed 457, so (q * q) is within 32bit; see: // vp10_convert_qindex_to_q(), vp10_ac_quant(), ac_qlookup*[]. cr->thresh_dist_sb = ((int64_t)(q * q)) << 2; // Set up segmentation. // Clear down the segment map. vp10_enable_segmentation(&cm->seg); vp10_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 vp10_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 BASE "Q" feature is disabled so it defaults to the baseline Q. vp10_disable_segfeature(seg, CR_SEGMENT_ID_BASE, SEG_LVL_ALT_Q); // Use segment BOOST1 for in-frame Q adjustment. vp10_enable_segfeature(seg, CR_SEGMENT_ID_BOOST1, SEG_LVL_ALT_Q); // Use segment BOOST2 for more aggressive in-frame Q adjustment. vp10_enable_segfeature(seg, CR_SEGMENT_ID_BOOST2, SEG_LVL_ALT_Q); // Set the q delta for segment BOOST1. qindex_delta = compute_deltaq(cpi, cm->base_qindex, cr->rate_ratio_qdelta); cr->qindex_delta[1] = qindex_delta; // Compute rd-mult for segment BOOST1. qindex2 = clamp(cm->base_qindex + cm->y_dc_delta_q + qindex_delta, 0, MAXQ); cr->rdmult = vp10_compute_rd_mult(cpi, qindex2); vp10_set_segdata(seg, CR_SEGMENT_ID_BOOST1, SEG_LVL_ALT_Q, qindex_delta); // Set a more aggressive (higher) q delta for segment BOOST2. qindex_delta = compute_deltaq( cpi, cm->base_qindex, MIN(CR_MAX_RATE_TARGET_RATIO, 0.1 * cr->rate_boost_fac * cr->rate_ratio_qdelta)); cr->qindex_delta[2] = qindex_delta; vp10_set_segdata(seg, CR_SEGMENT_ID_BOOST2, SEG_LVL_ALT_Q, qindex_delta); // Update the segmentation and refresh map. cyclic_refresh_update_map(cpi); } } int vp10_cyclic_refresh_get_rdmult(const CYCLIC_REFRESH *cr) { return cr->rdmult; } void vp10_cyclic_refresh_reset_resize(VP10_COMP *const cpi) { const VP10_COMMON *const cm = &cpi->common; CYCLIC_REFRESH *const cr = cpi->cyclic_refresh; memset(cr->map, 0, cm->mi_rows * cm->mi_cols); cr->sb_index = 0; cpi->refresh_golden_frame = 1; }