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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 17:32:43 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 17:32:43 +0000 |
commit | 6bf0a5cb5034a7e684dcc3500e841785237ce2dd (patch) | |
tree | a68f146d7fa01f0134297619fbe7e33db084e0aa /third_party/libwebrtc/sdk/android/src/java/org/webrtc/DynamicBitrateAdjuster.java | |
parent | Initial commit. (diff) | |
download | thunderbird-upstream.tar.xz thunderbird-upstream.zip |
Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/libwebrtc/sdk/android/src/java/org/webrtc/DynamicBitrateAdjuster.java')
-rw-r--r-- | third_party/libwebrtc/sdk/android/src/java/org/webrtc/DynamicBitrateAdjuster.java | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/third_party/libwebrtc/sdk/android/src/java/org/webrtc/DynamicBitrateAdjuster.java b/third_party/libwebrtc/sdk/android/src/java/org/webrtc/DynamicBitrateAdjuster.java new file mode 100644 index 0000000000..96a15bbfe1 --- /dev/null +++ b/third_party/libwebrtc/sdk/android/src/java/org/webrtc/DynamicBitrateAdjuster.java @@ -0,0 +1,98 @@ +/* + * Copyright 2017 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. + */ + +package org.webrtc; + +/** + * BitrateAdjuster that tracks the bandwidth produced by an encoder and dynamically adjusts the + * bitrate. Used for hardware codecs that pay attention to framerate but still deviate from the + * target bitrate by unacceptable margins. + */ +class DynamicBitrateAdjuster extends BaseBitrateAdjuster { + // Change the bitrate at most once every three seconds. + private static final double BITRATE_ADJUSTMENT_SEC = 3.0; + // Maximum bitrate adjustment scale - no more than 4 times. + private static final double BITRATE_ADJUSTMENT_MAX_SCALE = 4; + // Amount of adjustment steps to reach maximum scale. + private static final int BITRATE_ADJUSTMENT_STEPS = 20; + + private static final double BITS_PER_BYTE = 8.0; + + // How far the codec has deviated above (or below) the target bitrate (tracked in bytes). + private double deviationBytes; + private double timeSinceLastAdjustmentMs; + private int bitrateAdjustmentScaleExp; + + @Override + public void setTargets(int targetBitrateBps, double targetFramerateFps) { + if (this.targetBitrateBps > 0 && targetBitrateBps < this.targetBitrateBps) { + // Rescale the accumulator level if the accumulator max decreases + deviationBytes = deviationBytes * targetBitrateBps / this.targetBitrateBps; + } + super.setTargets(targetBitrateBps, targetFramerateFps); + } + + @Override + public void reportEncodedFrame(int size) { + if (targetFramerateFps == 0) { + return; + } + + // Accumulate the difference between actual and expected frame sizes. + double expectedBytesPerFrame = (targetBitrateBps / BITS_PER_BYTE) / targetFramerateFps; + deviationBytes += (size - expectedBytesPerFrame); + timeSinceLastAdjustmentMs += 1000.0 / targetFramerateFps; + + // Adjust the bitrate when the encoder accumulates one second's worth of data in excess or + // shortfall of the target. + double deviationThresholdBytes = targetBitrateBps / BITS_PER_BYTE; + + // Cap the deviation, i.e., don't let it grow beyond some level to avoid using too old data for + // bitrate adjustment. This also prevents taking more than 3 "steps" in a given 3-second cycle. + double deviationCap = BITRATE_ADJUSTMENT_SEC * deviationThresholdBytes; + deviationBytes = Math.min(deviationBytes, deviationCap); + deviationBytes = Math.max(deviationBytes, -deviationCap); + + // Do bitrate adjustment every 3 seconds if actual encoder bitrate deviates too much + // from the target value. + if (timeSinceLastAdjustmentMs <= 1000 * BITRATE_ADJUSTMENT_SEC) { + return; + } + + if (deviationBytes > deviationThresholdBytes) { + // Encoder generates too high bitrate - need to reduce the scale. + int bitrateAdjustmentInc = (int) (deviationBytes / deviationThresholdBytes + 0.5); + bitrateAdjustmentScaleExp -= bitrateAdjustmentInc; + // Don't let the adjustment scale drop below -BITRATE_ADJUSTMENT_STEPS. + // This sets a minimum exponent of -1 (bitrateAdjustmentScaleExp / BITRATE_ADJUSTMENT_STEPS). + bitrateAdjustmentScaleExp = Math.max(bitrateAdjustmentScaleExp, -BITRATE_ADJUSTMENT_STEPS); + deviationBytes = deviationThresholdBytes; + } else if (deviationBytes < -deviationThresholdBytes) { + // Encoder generates too low bitrate - need to increase the scale. + int bitrateAdjustmentInc = (int) (-deviationBytes / deviationThresholdBytes + 0.5); + bitrateAdjustmentScaleExp += bitrateAdjustmentInc; + // Don't let the adjustment scale exceed BITRATE_ADJUSTMENT_STEPS. + // This sets a maximum exponent of 1 (bitrateAdjustmentScaleExp / BITRATE_ADJUSTMENT_STEPS). + bitrateAdjustmentScaleExp = Math.min(bitrateAdjustmentScaleExp, BITRATE_ADJUSTMENT_STEPS); + deviationBytes = -deviationThresholdBytes; + } + timeSinceLastAdjustmentMs = 0; + } + + private double getBitrateAdjustmentScale() { + return Math.pow(BITRATE_ADJUSTMENT_MAX_SCALE, + (double) bitrateAdjustmentScaleExp / BITRATE_ADJUSTMENT_STEPS); + } + + @Override + public int getAdjustedBitrateBps() { + return (int) (targetBitrateBps * getBitrateAdjustmentScale()); + } +} |