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/*
* Copyright (c) 2019 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.
*/
#ifndef VIDEO_ENCODER_BITRATE_ADJUSTER_H_
#define VIDEO_ENCODER_BITRATE_ADJUSTER_H_
#include <memory>
#include "api/video/encoded_image.h"
#include "api/video/video_bitrate_allocation.h"
#include "api/video_codecs/video_encoder.h"
#include "video/encoder_overshoot_detector.h"
namespace webrtc {
class EncoderBitrateAdjuster {
public:
// Size of sliding window used to track overshoot rate.
static constexpr int64_t kWindowSizeMs = 3000;
// Minimum number of frames since last layout change required to trust the
// overshoot statistics. Otherwise falls back to default utilization.
// By layout change, we mean any spatial/temporal layer being either enabled
// or disabled.
static constexpr size_t kMinFramesSinceLayoutChange = 30;
// Default utilization, before reliable metrics are available, is set to 20%
// overshoot. This is conservative so that badly misbehaving encoders don't
// build too much queue at the very start.
static constexpr double kDefaultUtilizationFactor = 1.2;
explicit EncoderBitrateAdjuster(const VideoCodec& codec_settings);
~EncoderBitrateAdjuster();
// Adjusts the given rate allocation to make it paceable within the target
// rates.
VideoBitrateAllocation AdjustRateAllocation(
const VideoEncoder::RateControlParameters& rates);
// Updated overuse detectors with data about the encoder, specifically about
// the temporal layer frame rate allocation.
void OnEncoderInfo(const VideoEncoder::EncoderInfo& encoder_info);
// Updates the overuse detectors according to the encoded image size.
void OnEncodedFrame(DataSize size, int spatial_index, int temporal_index);
void Reset();
private:
const bool utilize_bandwidth_headroom_;
VideoEncoder::RateControlParameters current_rate_control_parameters_;
// FPS allocation of temporal layers, per spatial layer. Represented as a Q8
// fraction; 0 = 0%, 255 = 100%. See VideoEncoder::EncoderInfo.fps_allocation.
absl::InlinedVector<uint8_t, kMaxTemporalStreams>
current_fps_allocation_[kMaxSpatialLayers];
// Frames since layout was changed, mean that any spatial or temporal layer
// was either disabled or enabled.
size_t frames_since_layout_change_;
std::unique_ptr<EncoderOvershootDetector>
overshoot_detectors_[kMaxSpatialLayers][kMaxTemporalStreams];
// Minimum bitrates allowed, per spatial layer.
uint32_t min_bitrates_bps_[kMaxSpatialLayers];
};
} // namespace webrtc
#endif // VIDEO_ENCODER_BITRATE_ADJUSTER_H_
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