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86684960b3
The configurator decides number of spatial layers, their resolution and bitrate thresholds based on given input resolution and maximum number of spatial layers. The allocator distributes available bitrate across spatial and temporal layers. If there is not enough bitrate to provide acceptable quality for all spatial layers allocator disables enhancement layers one by one until the condition is met or number of layers is reduced to one. VP9 SVC related unit tests have been updated. Input resolution and bitrate in these tests have been increased to the level enough to provide desirable number of spatial layers. Bug: webrtc:8518 Change-Id: I9df790920227c7f7dd4d42a50a856c22f0f4389b Reviewed-on: https://webrtc-review.googlesource.com/60340 Commit-Queue: Sergey Silkin <ssilkin@webrtc.org> Reviewed-by: Erik Språng <sprang@webrtc.org> Reviewed-by: Stefan Holmer <stefan@webrtc.org> Reviewed-by: Rasmus Brandt <brandtr@webrtc.org> Reviewed-by: Michael Horowitz <mhoro@webrtc.org> Cr-Commit-Position: refs/heads/master@{#22672}
67 lines
2.7 KiB
C++
67 lines
2.7 KiB
C++
/*
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* Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/video_coding/codecs/vp9/svc_config.h"
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#include <algorithm>
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#include <cmath>
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#include <vector>
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#include "modules/video_coding/include/video_codec_interface.h"
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namespace webrtc {
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std::vector<SpatialLayer> GetSvcConfig(size_t input_width,
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size_t input_height,
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size_t num_spatial_layers,
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size_t num_temporal_layers) {
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RTC_DCHECK_GT(input_width, 0);
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RTC_DCHECK_GT(input_height, 0);
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RTC_DCHECK_GT(num_spatial_layers, 0);
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RTC_DCHECK_GT(num_temporal_layers, 0);
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std::vector<SpatialLayer> spatial_layers;
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// Limit number of layers for given resolution.
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const size_t num_layers_fit_horz = static_cast<size_t>(std::floor(
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1 + std::max(0.0f,
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std::log2(1.0f * input_width / kMinVp9SpatialLayerWidth))));
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const size_t num_layers_fit_vert = static_cast<size_t>(
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std::floor(1 + std::max(0.0f, std::log2(1.0f * input_height /
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kMinVp9SpatialLayerHeight))));
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num_spatial_layers =
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std::min({num_spatial_layers, num_layers_fit_horz, num_layers_fit_vert});
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for (size_t sl_idx = 0; sl_idx < num_spatial_layers; ++sl_idx) {
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SpatialLayer spatial_layer = {0};
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spatial_layer.width = input_width >> (num_spatial_layers - sl_idx - 1);
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spatial_layer.height = input_height >> (num_spatial_layers - sl_idx - 1);
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spatial_layer.numberOfTemporalLayers = num_temporal_layers;
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// minBitrate and maxBitrate formulas were derived to fit VP9
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// subjective-quality data for bit rate below which video quality is
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// unacceptable and above which additional bits do not provide benefit.
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// TODO(ssilkin): Add to the comment PSNR/SSIM we get at encoding certain
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// video to min/max bitrate specified by those formulas.
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const size_t num_pixels = spatial_layer.width * spatial_layer.height;
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spatial_layer.minBitrate =
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static_cast<int>(360 * std::sqrt(num_pixels) / 1000);
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spatial_layer.maxBitrate =
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static_cast<int>((1.5 * num_pixels + 75 * 1000) / 1000);
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spatial_layer.targetBitrate =
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(spatial_layer.maxBitrate - spatial_layer.minBitrate) / 2;
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spatial_layers.push_back(spatial_layer);
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}
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return spatial_layers;
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}
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} // namespace webrtc
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