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/*
* Copyright (c) 2020 The WebRTC 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 "modules/video_coding/codecs/av1/av1_svc_config.h"
#include <algorithm>
#include <cmath>
#include <memory>
#include "modules/video_coding/svc/create_scalability_structure.h"
#include "modules/video_coding/svc/scalability_mode_util.h"
#include "modules/video_coding/svc/scalable_video_controller.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/strings/string_builder.h"
namespace webrtc {
namespace {
const int kMinAv1SpatialLayerLongSideLength = 240;
const int kMinAv1SpatialLayerShortSideLength = 135;
int GetLimitedNumSpatialLayers(int width, int height) {
const bool is_landscape = width >= height;
const int min_width = is_landscape ? kMinAv1SpatialLayerLongSideLength
: kMinAv1SpatialLayerShortSideLength;
const int min_height = is_landscape ? kMinAv1SpatialLayerShortSideLength
: kMinAv1SpatialLayerLongSideLength;
const int num_layers_fit_horz = static_cast<int>(
std::floor(1 + std::max(0.0f, std::log2(1.0f * width / min_width))));
const int num_layers_fit_vert = static_cast<int>(
std::floor(1 + std::max(0.0f, std::log2(1.0f * height / min_height))));
return std::min(num_layers_fit_horz, num_layers_fit_vert);
}
absl::optional<ScalabilityMode> BuildScalabilityMode(int num_temporal_layers,
int num_spatial_layers) {
char name[20];
rtc::SimpleStringBuilder ss(name);
ss << "L" << num_spatial_layers << "T" << num_temporal_layers;
if (num_spatial_layers > 1) {
ss << "_KEY";
}
return ScalabilityModeFromString(name);
}
} // namespace
absl::InlinedVector<ScalabilityMode, kScalabilityModeCount>
LibaomAv1EncoderSupportedScalabilityModes() {
absl::InlinedVector<ScalabilityMode, kScalabilityModeCount> scalability_modes;
for (ScalabilityMode scalability_mode : kAllScalabilityModes) {
if (ScalabilityStructureConfig(scalability_mode) != absl::nullopt) {
scalability_modes.push_back(scalability_mode);
}
}
return scalability_modes;
}
bool LibaomAv1EncoderSupportsScalabilityMode(ScalabilityMode scalability_mode) {
// For libaom AV1, the scalability mode is supported if we can create the
// scalability structure.
return ScalabilityStructureConfig(scalability_mode) != absl::nullopt;
}
bool SetAv1SvcConfig(VideoCodec& video_codec,
int num_temporal_layers,
int num_spatial_layers) {
RTC_DCHECK_EQ(video_codec.codecType, kVideoCodecAV1);
absl::optional<ScalabilityMode> scalability_mode =
video_codec.GetScalabilityMode();
if (!scalability_mode.has_value()) {
scalability_mode =
BuildScalabilityMode(num_temporal_layers, num_spatial_layers);
if (!scalability_mode) {
RTC_LOG(LS_WARNING) << "Scalability mode is not set, using 'L1T1'.";
scalability_mode = ScalabilityMode::kL1T1;
}
}
bool configured_for_single_spatial_layer =
ScalabilityModeToNumSpatialLayers(*scalability_mode) == 1;
if (ScalabilityMode reduced = LimitNumSpatialLayers(
*scalability_mode,
GetLimitedNumSpatialLayers(video_codec.width, video_codec.height));
*scalability_mode != reduced) {
RTC_LOG(LS_WARNING) << "Reduced number of spatial layers from "
<< ScalabilityModeToString(*scalability_mode) << " to "
<< ScalabilityModeToString(reduced);
scalability_mode = reduced;
}
std::unique_ptr<ScalableVideoController> structure =
CreateScalabilityStructure(*scalability_mode);
if (structure == nullptr) {
RTC_LOG(LS_WARNING) << "Failed to create structure "
<< static_cast<int>(*scalability_mode);
return false;
}
video_codec.SetScalabilityMode(*scalability_mode);
ScalableVideoController::StreamLayersConfig info = structure->StreamConfig();
for (int sl_idx = 0; sl_idx < info.num_spatial_layers; ++sl_idx) {
SpatialLayer& spatial_layer = video_codec.spatialLayers[sl_idx];
spatial_layer.width = video_codec.width * info.scaling_factor_num[sl_idx] /
info.scaling_factor_den[sl_idx];
spatial_layer.height = video_codec.height *
info.scaling_factor_num[sl_idx] /
info.scaling_factor_den[sl_idx];
spatial_layer.maxFramerate = video_codec.maxFramerate;
spatial_layer.numberOfTemporalLayers = info.num_temporal_layers;
spatial_layer.active = true;
}
if (configured_for_single_spatial_layer) {
SpatialLayer& spatial_layer = video_codec.spatialLayers[0];
spatial_layer.minBitrate = video_codec.minBitrate;
spatial_layer.maxBitrate = video_codec.maxBitrate;
spatial_layer.targetBitrate =
(video_codec.minBitrate + video_codec.maxBitrate) / 2;
return true;
}
for (int sl_idx = 0; sl_idx < info.num_spatial_layers; ++sl_idx) {
SpatialLayer& spatial_layer = video_codec.spatialLayers[sl_idx];
const int num_pixels = spatial_layer.width * spatial_layer.height;
int min_bitrate_kbps = (480.0 * std::sqrt(num_pixels) - 95'000.0) / 1000.0;
spatial_layer.minBitrate = std::max(min_bitrate_kbps, 20);
spatial_layer.maxBitrate = 50 + static_cast<int>(1.6 * num_pixels / 1000.0);
spatial_layer.targetBitrate =
(spatial_layer.minBitrate + spatial_layer.maxBitrate) / 2;
}
return true;
}
} // namespace webrtc
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