ref: bf3fe26f7e1b51ac3578bdd27616f8c3b6e9b7d3
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
}