diff options
Diffstat (limited to 'third_party/libwebrtc/sdk/android/src/java/org/webrtc/audio/LowLatencyAudioBufferManager.java')
-rw-r--r-- | third_party/libwebrtc/sdk/android/src/java/org/webrtc/audio/LowLatencyAudioBufferManager.java | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/third_party/libwebrtc/sdk/android/src/java/org/webrtc/audio/LowLatencyAudioBufferManager.java b/third_party/libwebrtc/sdk/android/src/java/org/webrtc/audio/LowLatencyAudioBufferManager.java new file mode 100644 index 0000000000..70c625ab4f --- /dev/null +++ b/third_party/libwebrtc/sdk/android/src/java/org/webrtc/audio/LowLatencyAudioBufferManager.java @@ -0,0 +1,81 @@ +/* + * Copyright (c) 2020 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.audio; + +import android.media.AudioTrack; +import android.os.Build; +import org.webrtc.Logging; + +// Lowers the buffer size if no underruns are detected for 100 ms. Once an +// underrun is detected, the buffer size is increased by 10 ms and it will not +// be lowered further. The buffer size will never be increased more than +// 5 times, to avoid the possibility of the buffer size increasing without +// bounds. +class LowLatencyAudioBufferManager { + private static final String TAG = "LowLatencyAudioBufferManager"; + // The underrun count that was valid during the previous call to maybeAdjustBufferSize(). Used to + // detect increases in the value. + private int prevUnderrunCount; + // The number of ticks to wait without an underrun before decreasing the buffer size. + private int ticksUntilNextDecrease; + // Indicate if we should continue to decrease the buffer size. + private boolean keepLoweringBufferSize; + // How often the buffer size was increased. + private int bufferIncreaseCounter; + + public LowLatencyAudioBufferManager() { + this.prevUnderrunCount = 0; + this.ticksUntilNextDecrease = 10; + this.keepLoweringBufferSize = true; + this.bufferIncreaseCounter = 0; + } + + public void maybeAdjustBufferSize(AudioTrack audioTrack) { + if (Build.VERSION.SDK_INT >= 26) { + final int underrunCount = audioTrack.getUnderrunCount(); + if (underrunCount > prevUnderrunCount) { + // Don't increase buffer more than 5 times. Continuing to increase the buffer size + // could be harmful on low-power devices that regularly experience underruns under + // normal conditions. + if (bufferIncreaseCounter < 5) { + // Underrun detected, increase buffer size by 10ms. + final int currentBufferSize = audioTrack.getBufferSizeInFrames(); + final int newBufferSize = currentBufferSize + audioTrack.getPlaybackRate() / 100; + Logging.d(TAG, + "Underrun detected! Increasing AudioTrack buffer size from " + currentBufferSize + + " to " + newBufferSize); + audioTrack.setBufferSizeInFrames(newBufferSize); + bufferIncreaseCounter++; + } + // Stop trying to lower the buffer size. + keepLoweringBufferSize = false; + prevUnderrunCount = underrunCount; + ticksUntilNextDecrease = 10; + } else if (keepLoweringBufferSize) { + ticksUntilNextDecrease--; + if (ticksUntilNextDecrease <= 0) { + // No underrun seen for 100 ms, try to lower the buffer size by 10ms. + final int bufferSize10ms = audioTrack.getPlaybackRate() / 100; + // Never go below a buffer size of 10ms. + final int currentBufferSize = audioTrack.getBufferSizeInFrames(); + final int newBufferSize = Math.max(bufferSize10ms, currentBufferSize - bufferSize10ms); + if (newBufferSize != currentBufferSize) { + Logging.d(TAG, + "Lowering AudioTrack buffer size from " + currentBufferSize + " to " + + newBufferSize); + audioTrack.setBufferSizeInFrames(newBufferSize); + } + ticksUntilNextDecrease = 10; + } + } + } + } +} |