93 lines
3.5 KiB
C++
93 lines
3.5 KiB
C++
/*
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* Copyright 2016 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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#ifndef COMMON_VIDEO_INCLUDE_BITRATE_ADJUSTER_H_
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#define COMMON_VIDEO_INCLUDE_BITRATE_ADJUSTER_H_
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#include <stddef.h>
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#include <stdint.h>
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#include "absl/types/optional.h"
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#include "rtc_base/rate_statistics.h"
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#include "rtc_base/synchronization/mutex.h"
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#include "rtc_base/system/rtc_export.h"
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#include "rtc_base/thread_annotations.h"
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namespace webrtc {
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// Certain hardware encoders tend to consistently overshoot the bitrate that
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// they are configured to encode at. This class estimates an adjusted bitrate
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// that when set on the encoder will produce the desired bitrate.
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class RTC_EXPORT BitrateAdjuster {
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public:
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// min_adjusted_bitrate_pct and max_adjusted_bitrate_pct are the lower and
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// upper bound outputted adjusted bitrates as a percentage of the target
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// bitrate.
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BitrateAdjuster(float min_adjusted_bitrate_pct,
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float max_adjusted_bitrate_pct);
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virtual ~BitrateAdjuster() {}
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static const uint32_t kBitrateUpdateIntervalMs;
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static const uint32_t kBitrateUpdateFrameInterval;
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static const float kBitrateTolerancePct;
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static const float kBytesPerMsToBitsPerSecond;
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// Sets the desired bitrate in bps (bits per second).
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// Should be called at least once before Update.
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void SetTargetBitrateBps(uint32_t bitrate_bps);
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uint32_t GetTargetBitrateBps() const;
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// Returns the adjusted bitrate in bps.
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uint32_t GetAdjustedBitrateBps() const;
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// Returns what we think the current bitrate is.
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absl::optional<uint32_t> GetEstimatedBitrateBps();
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// This should be called after each frame is encoded. The timestamp at which
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// it is called is used to estimate the output bitrate of the encoder.
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// Should be called from only one thread.
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void Update(size_t frame_size);
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private:
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// Returns true if the bitrate is within kBitrateTolerancePct of bitrate_bps.
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bool IsWithinTolerance(uint32_t bitrate_bps, uint32_t target_bitrate_bps);
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// Returns smallest possible adjusted value.
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uint32_t GetMinAdjustedBitrateBps() const
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RTC_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
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// Returns largest possible adjusted value.
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uint32_t GetMaxAdjustedBitrateBps() const
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RTC_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
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void Reset();
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void UpdateBitrate(uint32_t current_time_ms)
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RTC_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
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mutable Mutex mutex_;
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const float min_adjusted_bitrate_pct_;
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const float max_adjusted_bitrate_pct_;
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// The bitrate we want.
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volatile uint32_t target_bitrate_bps_ RTC_GUARDED_BY(mutex_);
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// The bitrate we use to get what we want.
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volatile uint32_t adjusted_bitrate_bps_ RTC_GUARDED_BY(mutex_);
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// The target bitrate that the adjusted bitrate was computed from.
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volatile uint32_t last_adjusted_target_bitrate_bps_ RTC_GUARDED_BY(mutex_);
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// Used to estimate bitrate.
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RateStatistics bitrate_tracker_ RTC_GUARDED_BY(mutex_);
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// The last time we tried to adjust the bitrate.
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uint32_t last_bitrate_update_time_ms_ RTC_GUARDED_BY(mutex_);
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// The number of frames since the last time we tried to adjust the bitrate.
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uint32_t frames_since_last_update_ RTC_GUARDED_BY(mutex_);
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};
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} // namespace webrtc
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#endif // COMMON_VIDEO_INCLUDE_BITRATE_ADJUSTER_H_
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