| /* |
| * 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 "vp9/common/vp9_seg_common.h" |
| |
| #include "vp9/encoder/vp9_segmentation.h" |
| |
| #define AQ_C_SEGMENTS 3 |
| #define AQ_C_STRENGTHS 3 |
| static const int aq_c_active_segments[AQ_C_STRENGTHS] = {1, 2, 3}; |
| static const double aq_c_q_adj_factor[AQ_C_STRENGTHS][AQ_C_SEGMENTS] = |
| {{1.0, 1.0, 1.0}, {1.0, 2.0, 1.0}, {1.0, 1.5, 2.5}}; |
| static const double aq_c_transitions[AQ_C_STRENGTHS][AQ_C_SEGMENTS] = |
| {{1.0, 1.0, 1.0}, {1.0, 0.25, 0.0}, {1.0, 0.5, 0.25}}; |
| |
| static int get_aq_c_strength(int q_index) { |
| // Approximate base quatizer (truncated to int) |
| int base_quant = vp9_ac_quant(q_index, 0) / 4; |
| return (base_quant > 20) + (base_quant > 45); |
| } |
| |
| void vp9_setup_in_frame_q_adj(VP9_COMP *cpi) { |
| VP9_COMMON *const cm = &cpi->common; |
| struct segmentation *const seg = &cm->seg; |
| |
| // Make SURE use of floating point in this function is safe. |
| vp9_clear_system_state(); |
| |
| if (cm->frame_type == KEY_FRAME || |
| cpi->refresh_alt_ref_frame || |
| (cpi->refresh_golden_frame && !cpi->rc.is_src_frame_alt_ref)) { |
| int segment; |
| const int aq_strength = get_aq_c_strength(cm->base_qindex); |
| const int active_segments = aq_c_active_segments[aq_strength]; |
| |
| // Clear down the segment map. |
| vpx_memset(cpi->segmentation_map, 0, cm->mi_rows * cm->mi_cols); |
| |
| // Clear down the complexity map used for rd. |
| vpx_memset(cpi->complexity_map, 0, cm->mi_rows * cm->mi_cols); |
| |
| vp9_clearall_segfeatures(seg); |
| |
| // Segmentation only makes sense if the target bits per SB is above a |
| // threshold. Below this the overheads will usually outweigh any benefit. |
| if (cpi->rc.sb64_target_rate < 256) { |
| vp9_disable_segmentation(seg); |
| return; |
| } |
| |
| vp9_enable_segmentation(seg); |
| |
| // Select delta coding method. |
| seg->abs_delta = SEGMENT_DELTADATA; |
| |
| // Segment 0 "Q" feature is disabled so it defaults to the baseline Q. |
| vp9_disable_segfeature(seg, 0, SEG_LVL_ALT_Q); |
| |
| // Use some of the segments for in frame Q adjustment. |
| for (segment = 1; segment < active_segments; ++segment) { |
| int qindex_delta = |
| vp9_compute_qdelta_by_rate(&cpi->rc, cm->frame_type, cm->base_qindex, |
| aq_c_q_adj_factor[aq_strength][segment]); |
| |
| // For AQ complexity mode, we dont allow Q0 in a segment if the base |
| // Q is not 0. Q0 (lossless) implies 4x4 only and in AQ mode 2 a segment |
| // Q delta is sometimes applied without going back around the rd loop. |
| // This could lead to an illegal combination of partition size and q. |
| if ((cm->base_qindex != 0) && ((cm->base_qindex + qindex_delta) == 0)) { |
| qindex_delta = -cm->base_qindex + 1; |
| } |
| if ((cm->base_qindex + qindex_delta) > 0) { |
| vp9_enable_segfeature(seg, segment, SEG_LVL_ALT_Q); |
| vp9_set_segdata(seg, segment, SEG_LVL_ALT_Q, qindex_delta); |
| } |
| } |
| } |
| } |
| |
| // Select a segment for the current SB64 block. |
| // The choice of segment for a block depends on the ratio of the projected |
| // bits for the block vs a target average. |
| // An "aq_strength" value determines how many segments are supported, |
| // the set of transition points to use and the extent of the quantizer |
| // adjustment for each segment (configured in vp9_setup_in_frame_q_adj()). |
| void vp9_select_in_frame_q_segment(VP9_COMP *cpi, |
| int mi_row, int mi_col, |
| int output_enabled, int projected_rate) { |
| VP9_COMMON *const cm = &cpi->common; |
| |
| const int mi_offset = mi_row * cm->mi_cols + mi_col; |
| const int bw = num_8x8_blocks_wide_lookup[BLOCK_64X64]; |
| const int bh = num_8x8_blocks_high_lookup[BLOCK_64X64]; |
| const int xmis = MIN(cm->mi_cols - mi_col, bw); |
| const int ymis = MIN(cm->mi_rows - mi_row, bh); |
| int complexity_metric = 64; |
| int x, y; |
| |
| unsigned char segment; |
| |
| if (!output_enabled) { |
| segment = 0; |
| } else { |
| // Rate depends on fraction of a SB64 in frame (xmis * ymis / bw * bh). |
| // It is converted to bits * 256 units. |
| const int target_rate = (cpi->rc.sb64_target_rate * xmis * ymis * 256) / |
| (bw * bh); |
| const int aq_strength = get_aq_c_strength(cm->base_qindex); |
| const int active_segments = aq_c_active_segments[aq_strength]; |
| |
| // The number of segments considered and the transition points used to |
| // select them is determined by the "aq_strength" value. |
| // Currently this loop only supports segments that reduce Q (i.e. where |
| // there is undershoot. |
| // The loop counts down towards segment 0 which is the default segment |
| // with no Q adjustment. |
| segment = active_segments - 1; |
| while (segment > 0) { |
| if (projected_rate < |
| (target_rate * aq_c_transitions[aq_strength][segment])) { |
| break; |
| } |
| --segment; |
| } |
| |
| if (target_rate > 0) { |
| complexity_metric = |
| clamp((int)((projected_rate * 64) / target_rate), 16, 255); |
| } |
| } |
| |
| // Fill in the entires in the segment map corresponding to this SB64. |
| for (y = 0; y < ymis; y++) { |
| for (x = 0; x < xmis; x++) { |
| cpi->segmentation_map[mi_offset + y * cm->mi_cols + x] = segment; |
| cpi->complexity_map[mi_offset + y * cm->mi_cols + x] = |
| (unsigned char)complexity_metric; |
| } |
| } |
| } |