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