Bitrate controller for VideoToolbox encoder.
Also fixes a crash on encoder Release.
BUG=webrtc:4081
Review URL: https://codereview.webrtc.org/1660963002
Cr-Commit-Position: refs/heads/master@{#11729}
diff --git a/webrtc/modules/video_coding/include/bitrate_adjuster.h b/webrtc/modules/video_coding/include/bitrate_adjuster.h
new file mode 100644
index 0000000..8c9143f
--- /dev/null
+++ b/webrtc/modules/video_coding/include/bitrate_adjuster.h
@@ -0,0 +1,90 @@
+/*
+ * 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.
+ */
+
+#ifndef WEBRTC_MODULES_VIDEO_CODING_INCLUDE_BITRATE_ADJUSTER_H_
+#define WEBRTC_MODULES_VIDEO_CODING_INCLUDE_BITRATE_ADJUSTER_H_
+
+#include <functional>
+
+#include "webrtc/base/criticalsection.h"
+#include "webrtc/base/gtest_prod_util.h"
+#include "webrtc/base/rate_statistics.h"
+
+namespace webrtc {
+
+class Clock;
+
+// 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 BitrateAdjuster {
+ public:
+ // 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(Clock* clock,
+ 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.
+ 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);
+
+ private:
+ // 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 EXCLUSIVE_LOCKS_REQUIRED(crit_);
+ // Returns largest possible adjusted value.
+ uint32_t GetMaxAdjustedBitrateBps() const EXCLUSIVE_LOCKS_REQUIRED(crit_);
+
+ void Reset();
+ void UpdateBitrate(uint32_t current_time_ms) EXCLUSIVE_LOCKS_REQUIRED(crit_);
+
+ rtc::CriticalSection crit_;
+ Clock* const clock_;
+ const float min_adjusted_bitrate_pct_;
+ const float max_adjusted_bitrate_pct_;
+ // The bitrate we want.
+ volatile uint32_t target_bitrate_bps_ GUARDED_BY(crit_);
+ // The bitrate we use to get what we want.
+ volatile uint32_t adjusted_bitrate_bps_ GUARDED_BY(crit_);
+ // The target bitrate that the adjusted bitrate was computed from.
+ volatile uint32_t last_adjusted_target_bitrate_bps_ GUARDED_BY(crit_);
+ // Used to estimate bitrate.
+ RateStatistics bitrate_tracker_ GUARDED_BY(crit_);
+ // The last time we tried to adjust the bitrate.
+ uint32_t last_bitrate_update_time_ms_ GUARDED_BY(crit_);
+ // The number of frames since the last time we tried to adjust the bitrate.
+ uint32_t frames_since_last_update_ GUARDED_BY(crit_);
+};
+
+} // namespace webrtc
+
+#endif // WEBRTC_MODULES_VIDEO_CODING_INCLUDE_BITRATE_ADJUSTER_H_