ref: 869d82d656eaea8f0db1df6364af4d22875103f4
dir: /vp9/encoder/vp9_noise_estimate.c/
/* * Copyright (c) 2015 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 <assert.h> #include <limits.h> #include <math.h> #include "./vpx_dsp_rtcd.h" #include "vpx_dsp/vpx_dsp_common.h" #include "vpx_scale/yv12config.h" #include "vpx/vpx_integer.h" #include "vp9/common/vp9_reconinter.h" #include "vp9/encoder/vp9_context_tree.h" #include "vp9/encoder/vp9_noise_estimate.h" #include "vp9/encoder/vp9_encoder.h" #if CONFIG_VP9_TEMPORAL_DENOISING // For SVC: only do noise estimation on top spatial layer. static INLINE int noise_est_svc(const struct VP9_COMP *const cpi) { return (!cpi->use_svc || (cpi->use_svc && cpi->svc.spatial_layer_id == cpi->svc.number_spatial_layers - 1)); } #endif void vp9_noise_estimate_init(NOISE_ESTIMATE *const ne, int width, int height) { ne->enabled = 0; ne->level = (width * height < 1280 * 720) ? kLowLow : kLow; ne->value = 0; ne->count = 0; ne->thresh = 90; ne->last_w = 0; ne->last_h = 0; if (width * height >= 1920 * 1080) { ne->thresh = 200; } else if (width * height >= 1280 * 720) { ne->thresh = 140; } else if (width * height >= 640 * 360) { ne->thresh = 115; } ne->num_frames_estimate = 15; ne->adapt_thresh = (3 * ne->thresh) >> 1; } static int enable_noise_estimation(VP9_COMP *const cpi) { #if CONFIG_VP9_HIGHBITDEPTH if (cpi->common.use_highbitdepth) return 0; #endif // Enable noise estimation if denoising is on. #if CONFIG_VP9_TEMPORAL_DENOISING if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi) && cpi->common.width >= 320 && cpi->common.height >= 180) return 1; #endif // Only allow noise estimate under certain encoding mode. // Enabled for 1 pass CBR, speed >=5, and if resolution is same as original. // Not enabled for SVC mode and screen_content_mode. // Not enabled for low resolutions. if (cpi->oxcf.pass == 0 && cpi->oxcf.rc_mode == VPX_CBR && cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ && cpi->oxcf.speed >= 5 && cpi->resize_state == ORIG && cpi->resize_pending == 0 && !cpi->use_svc && cpi->oxcf.content != VP9E_CONTENT_SCREEN && cpi->common.width * cpi->common.height >= 640 * 360) return 1; else return 0; } #if CONFIG_VP9_TEMPORAL_DENOISING static void copy_frame(YV12_BUFFER_CONFIG *const dest, const YV12_BUFFER_CONFIG *const src) { int r; const uint8_t *srcbuf = src->y_buffer; uint8_t *destbuf = dest->y_buffer; assert(dest->y_width == src->y_width); assert(dest->y_height == src->y_height); for (r = 0; r < dest->y_height; ++r) { memcpy(destbuf, srcbuf, dest->y_width); destbuf += dest->y_stride; srcbuf += src->y_stride; } } #endif // CONFIG_VP9_TEMPORAL_DENOISING NOISE_LEVEL vp9_noise_estimate_extract_level(NOISE_ESTIMATE *const ne) { int noise_level = kLowLow; if (ne->value > (ne->thresh << 1)) { noise_level = kHigh; } else { if (ne->value > ne->thresh) noise_level = kMedium; else if (ne->value > (ne->thresh >> 1)) noise_level = kLow; else noise_level = kLowLow; } return noise_level; } void vp9_update_noise_estimate(VP9_COMP *const cpi) { const VP9_COMMON *const cm = &cpi->common; NOISE_ESTIMATE *const ne = &cpi->noise_estimate; const int low_res = (cm->width <= 352 && cm->height <= 288); // Estimate of noise level every frame_period frames. int frame_period = 8; int thresh_consec_zeromv = 6; int frame_counter = cm->current_video_frame; // Estimate is between current source and last source. YV12_BUFFER_CONFIG *last_source = cpi->Last_Source; #if CONFIG_VP9_TEMPORAL_DENOISING if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi)) { last_source = &cpi->denoiser.last_source; // Tune these thresholds for different resolutions when denoising is // enabled. if (cm->width > 640 && cm->width <= 1920) { thresh_consec_zeromv = 2; } } #endif ne->enabled = enable_noise_estimation(cpi); if (cpi->svc.number_spatial_layers > 1) frame_counter = cpi->svc.current_superframe; if (!ne->enabled || frame_counter % frame_period != 0 || last_source == NULL || (cpi->svc.number_spatial_layers == 1 && (ne->last_w != cm->width || ne->last_h != cm->height))) { #if CONFIG_VP9_TEMPORAL_DENOISING if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi)) copy_frame(&cpi->denoiser.last_source, cpi->Source); #endif if (last_source != NULL) { ne->last_w = cm->width; ne->last_h = cm->height; } return; } else if (frame_counter > 60 && cpi->svc.num_encoded_top_layer > 1 && cpi->rc.frames_since_key > cpi->svc.number_spatial_layers && cpi->svc.spatial_layer_id == cpi->svc.number_spatial_layers - 1 && cpi->rc.avg_frame_low_motion < (low_res ? 60 : 40)) { // Force noise estimation to 0 and denoiser off if content has high motion. ne->level = kLowLow; ne->count = 0; ne->num_frames_estimate = 10; #if CONFIG_VP9_TEMPORAL_DENOISING if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi) && cpi->svc.current_superframe > 1) { vp9_denoiser_set_noise_level(cpi, ne->level); copy_frame(&cpi->denoiser.last_source, cpi->Source); } #endif return; } else { unsigned int bin_size = 100; unsigned int hist[MAX_VAR_HIST_BINS] = { 0 }; unsigned int hist_avg[MAX_VAR_HIST_BINS]; unsigned int max_bin = 0; unsigned int max_bin_count = 0; unsigned int bin_cnt; int bsize = BLOCK_16X16; // Loop over sub-sample of 16x16 blocks of frame, and for blocks that have // been encoded as zero/small mv at least x consecutive frames, compute // the variance to update estimate of noise in the source. const uint8_t *src_y = cpi->Source->y_buffer; const int src_ystride = cpi->Source->y_stride; const uint8_t *last_src_y = last_source->y_buffer; const int last_src_ystride = last_source->y_stride; const uint8_t *src_u = cpi->Source->u_buffer; const uint8_t *src_v = cpi->Source->v_buffer; const int src_uvstride = cpi->Source->uv_stride; int mi_row, mi_col; int num_low_motion = 0; int frame_low_motion = 1; for (mi_row = 0; mi_row < cm->mi_rows; mi_row++) { for (mi_col = 0; mi_col < cm->mi_cols; mi_col++) { int bl_index = mi_row * cm->mi_cols + mi_col; if (cpi->consec_zero_mv[bl_index] > thresh_consec_zeromv) num_low_motion++; } } if (num_low_motion < ((3 * cm->mi_rows * cm->mi_cols) >> 3)) frame_low_motion = 0; for (mi_row = 0; mi_row < cm->mi_rows; mi_row++) { for (mi_col = 0; mi_col < cm->mi_cols; mi_col++) { // 16x16 blocks, 1/4 sample of frame. if (mi_row % 4 == 0 && mi_col % 4 == 0 && mi_row < cm->mi_rows - 1 && mi_col < cm->mi_cols - 1) { int bl_index = mi_row * cm->mi_cols + mi_col; int bl_index1 = bl_index + 1; int bl_index2 = bl_index + cm->mi_cols; int bl_index3 = bl_index2 + 1; int consec_zeromv = VPXMIN(cpi->consec_zero_mv[bl_index], VPXMIN(cpi->consec_zero_mv[bl_index1], VPXMIN(cpi->consec_zero_mv[bl_index2], cpi->consec_zero_mv[bl_index3]))); // Only consider blocks that are likely steady background. i.e, have // been encoded as zero/low motion x (= thresh_consec_zeromv) frames // in a row. consec_zero_mv[] defined for 8x8 blocks, so consider all // 4 sub-blocks for 16x16 block. And exclude this frame if // high_source_sad is true (i.e., scene/content change). if (frame_low_motion && consec_zeromv > thresh_consec_zeromv && !cpi->rc.high_source_sad && !cpi->svc.high_source_sad_superframe) { int is_skin = 0; if (cpi->use_skin_detection) { is_skin = vp9_compute_skin_block(src_y, src_u, src_v, src_ystride, src_uvstride, bsize, consec_zeromv, 0); } if (!is_skin) { unsigned int sse; // Compute variance between co-located blocks from current and // last input frames. unsigned int variance = cpi->fn_ptr[bsize].vf( src_y, src_ystride, last_src_y, last_src_ystride, &sse); unsigned int hist_index = variance / bin_size; if (hist_index < MAX_VAR_HIST_BINS) hist[hist_index]++; else if (hist_index < 3 * (MAX_VAR_HIST_BINS >> 1)) hist[MAX_VAR_HIST_BINS - 1]++; // Account for the tail } } } src_y += 8; last_src_y += 8; src_u += 4; src_v += 4; } src_y += (src_ystride << 3) - (cm->mi_cols << 3); last_src_y += (last_src_ystride << 3) - (cm->mi_cols << 3); src_u += (src_uvstride << 2) - (cm->mi_cols << 2); src_v += (src_uvstride << 2) - (cm->mi_cols << 2); } ne->last_w = cm->width; ne->last_h = cm->height; // Adjust histogram to account for effect that histogram flattens // and shifts to zero as scene darkens. if (hist[0] > 10 && (hist[MAX_VAR_HIST_BINS - 1] > hist[0] >> 2)) { hist[0] = 0; hist[1] >>= 2; hist[2] >>= 2; hist[3] >>= 2; hist[4] >>= 1; hist[5] >>= 1; hist[6] = 3 * hist[6] >> 1; hist[MAX_VAR_HIST_BINS - 1] >>= 1; } // Average hist[] and find largest bin for (bin_cnt = 0; bin_cnt < MAX_VAR_HIST_BINS; bin_cnt++) { if (bin_cnt == 0) hist_avg[bin_cnt] = (hist[0] + hist[1] + hist[2]) / 3; else if (bin_cnt == MAX_VAR_HIST_BINS - 1) hist_avg[bin_cnt] = hist[MAX_VAR_HIST_BINS - 1] >> 2; else if (bin_cnt == MAX_VAR_HIST_BINS - 2) hist_avg[bin_cnt] = (hist[bin_cnt - 1] + 2 * hist[bin_cnt] + (hist[bin_cnt + 1] >> 1) + 2) >> 2; else hist_avg[bin_cnt] = (hist[bin_cnt - 1] + 2 * hist[bin_cnt] + hist[bin_cnt + 1] + 2) >> 2; if (hist_avg[bin_cnt] > max_bin_count) { max_bin_count = hist_avg[bin_cnt]; max_bin = bin_cnt; } } // Scale by 40 to work with existing thresholds ne->value = (int)((3 * ne->value + max_bin * 40) >> 2); // Quickly increase VNR strength when the noise level increases suddenly. if (ne->level < kMedium && ne->value > ne->adapt_thresh) { ne->count = ne->num_frames_estimate; } else { ne->count++; } if (ne->count == ne->num_frames_estimate) { // Reset counter and check noise level condition. ne->num_frames_estimate = 30; ne->count = 0; ne->level = vp9_noise_estimate_extract_level(ne); #if CONFIG_VP9_TEMPORAL_DENOISING if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi)) vp9_denoiser_set_noise_level(cpi, ne->level); #endif } } #if CONFIG_VP9_TEMPORAL_DENOISING if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi)) copy_frame(&cpi->denoiser.last_source, cpi->Source); #endif }