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Make audio track min buffer size configurable.
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Move the code in its own class as DefaultAudioTrack
is getting very big. It also help for testability.

The new class is easily configurable and highly tested.
Manual test was used to catch any regression.

#8891

PiperOrigin-RevId: 424602011
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@krocard @andrewlewis
krocard authored and andrewlewis committed Jan 28, 2022
1 parent 777246d commit 901a5a4
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Showing 4 changed files with 610 additions and 118 deletions.
3 changes: 3 additions & 0 deletions RELEASENOTES.md
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Expand Up @@ -53,6 +53,9 @@
constructors.
* Change `AudioCapabilities` APIs to require passing explicitly
`AudioCapabilities.DEFAULT_AUDIO_CAPABILITIES` instead of `null`.
* Allow customization of the `AudioTrack` buffer size calculation by
injecting an `AudioTrackBufferSizeProvider` to `DefaultAudioSink`.
([#8891](https://github.com/google/ExoPlayer/issues/8891)).
* Extractors:
* Fix inconsistency with spec in H.265 SPS nal units parsing
([#9719](https://github.com/google/ExoPlayer/issues/9719)).
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198 changes: 80 additions & 118 deletions library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java
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Expand Up @@ -17,6 +17,7 @@

import static com.google.android.exoplayer2.audio.AudioCapabilities.DEFAULT_AUDIO_CAPABILITIES;
import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
import static com.google.android.exoplayer2.util.Util.constrainValue;
import static com.google.common.base.MoreObjects.firstNonNull;
import static java.lang.Math.max;
import static java.lang.Math.min;
Expand Down Expand Up @@ -209,6 +210,39 @@ public long getSkippedOutputFrameCount() {
}
}

/** Provides the buffer size to use when creating an {@link AudioTrack}. */
interface AudioTrackBufferSizeProvider {
/** Default instance. */
AudioTrackBufferSizeProvider DEFAULT =
new DefaultAudioTrackBufferSizeProvider.Builder().build();
/**
* Returns the buffer size to use when creating an {@link AudioTrack} for a specific format and
* output mode.
*
* @param minBufferSizeInBytes The minimum buffer size in bytes required to play this format.
* See {@link AudioTrack#getMinBufferSize}.
* @param encoding The {@link C.Encoding} of the format.
* @param outputMode How the audio will be played. One of the {@link OutputMode output modes}.
* @param pcmFrameSize The size of the PCM frames if the {@code encoding} is PCM, 1 otherwise,
* in bytes.
* @param sampleRate The sample rate of the format, in Hz.
* @param maxAudioTrackPlaybackSpeed The maximum speed the content will be played using {@link
* AudioTrack#setPlaybackParams}. 0.5 is 2x slow motion, 1 is real time, 2 is 2x fast
* forward, etc. This will be {@code 1} unless {@link
* Builder#setEnableAudioTrackPlaybackParams} is enabled.
* @return The computed buffer size in bytes. It should always be {@code >=
* minBufferSizeInBytes}. The computed buffer size must contain an integer number of frames:
* {@code bufferSizeInBytes % pcmFrameSize == 0}.
*/
int getBufferSizeInBytes(
int minBufferSizeInBytes,
@C.Encoding int encoding,
@OutputMode int outputMode,
int pcmFrameSize,
int sampleRate,
double maxAudioTrackPlaybackSpeed);
}

/** A builder to create {@link DefaultAudioSink} instances. */
public static final class Builder {

Expand All @@ -217,11 +251,13 @@ public static final class Builder {
private boolean enableFloatOutput;
private boolean enableAudioTrackPlaybackParams;
private int offloadMode;
AudioTrackBufferSizeProvider audioTrackBufferSizeProvider;

/** Creates a new builder. */
public Builder() {
audioCapabilities = DEFAULT_AUDIO_CAPABILITIES;
offloadMode = OFFLOAD_MODE_DISABLED;
audioTrackBufferSizeProvider = AudioTrackBufferSizeProvider.DEFAULT;
}

/**
Expand Down Expand Up @@ -302,6 +338,18 @@ public Builder setOffloadMode(@OffloadMode int offloadMode) {
return this;
}

/**
* Sets an {@link AudioTrackBufferSizeProvider} to compute the buffer size when {@link
* #configure} is called with {@code specifiedBufferSize == 0}.
*
* <p>The default value is {@link AudioTrackBufferSizeProvider#DEFAULT}.
*/
public Builder setAudioTrackBufferSizeProvider(
AudioTrackBufferSizeProvider audioTrackBufferSizeProvider) {
this.audioTrackBufferSizeProvider = audioTrackBufferSizeProvider;
return this;
}

/** Builds the {@link DefaultAudioSink}. Must only be called once per Builder instance. */
public DefaultAudioSink build() {
if (audioProcessorChain == null) {
Expand Down Expand Up @@ -362,31 +410,18 @@ public DefaultAudioSink build() {
*/
public static final int OFFLOAD_MODE_ENABLED_GAPLESS_DISABLED = 3;

/** Output mode of the audio sink. */
@Documented
@Retention(RetentionPolicy.SOURCE)
@IntDef({OUTPUT_MODE_PCM, OUTPUT_MODE_OFFLOAD, OUTPUT_MODE_PASSTHROUGH})
private @interface OutputMode {}
public @interface OutputMode {}

private static final int OUTPUT_MODE_PCM = 0;
private static final int OUTPUT_MODE_OFFLOAD = 1;
private static final int OUTPUT_MODE_PASSTHROUGH = 2;

/** A minimum length for the {@link AudioTrack} buffer, in microseconds. */
private static final long MIN_BUFFER_DURATION_US = 250_000;
/** A maximum length for the {@link AudioTrack} buffer, in microseconds. */
private static final long MAX_BUFFER_DURATION_US = 750_000;
/** The length for passthrough {@link AudioTrack} buffers, in microseconds. */
private static final long PASSTHROUGH_BUFFER_DURATION_US = 250_000;
/** The length for offload {@link AudioTrack} buffers, in microseconds. */
private static final long OFFLOAD_BUFFER_DURATION_US = 50_000_000;

/**
* A multiplication factor to apply to the minimum buffer size requested by the underlying {@link
* AudioTrack}.
*/
private static final int BUFFER_MULTIPLICATION_FACTOR = 4;
/** To avoid underruns on some devices (e.g., Broadcom 7271), scale up the AC3 buffer duration. */
private static final int AC3_BUFFER_MULTIPLICATION_FACTOR = 2;
/** The audio sink plays PCM audio. */
public static final int OUTPUT_MODE_PCM = 0;
/** The audio sink plays encoded audio in offload. */
public static final int OUTPUT_MODE_OFFLOAD = 1;
/** The audio sink plays encoded audio in passthrough. */
public static final int OUTPUT_MODE_PASSTHROUGH = 2;

/**
* Native error code equivalent of {@link AudioTrack#ERROR_DEAD_OBJECT} to workaround missing
Expand Down Expand Up @@ -433,6 +468,7 @@ public DefaultAudioSink build() {
private final PendingExceptionHolder<InitializationException>
initializationExceptionPendingExceptionHolder;
private final PendingExceptionHolder<WriteException> writeExceptionPendingExceptionHolder;
private final AudioTrackBufferSizeProvider audioTrackBufferSizeProvider;

@Nullable private PlayerId playerId;
@Nullable private Listener listener;
Expand Down Expand Up @@ -553,6 +589,7 @@ private DefaultAudioSink(Builder builder) {
enableFloatOutput = Util.SDK_INT >= 21 && builder.enableFloatOutput;
enableAudioTrackPlaybackParams = Util.SDK_INT >= 23 && builder.enableAudioTrackPlaybackParams;
offloadMode = Util.SDK_INT >= 29 ? builder.offloadMode : OFFLOAD_MODE_DISABLED;
audioTrackBufferSizeProvider = builder.audioTrackBufferSizeProvider;
releasingConditionVariable = new ConditionVariable(true);
audioTrackPositionTracker = new AudioTrackPositionTracker(new PositionTrackerListener());
channelMappingAudioProcessor = new ChannelMappingAudioProcessor();
Expand Down Expand Up @@ -715,6 +752,16 @@ public void configure(Format inputFormat, int specifiedBufferSize, @Nullable int
outputChannelConfig = encodingAndChannelConfig.second;
}
}
int bufferSize =
specifiedBufferSize != 0
? specifiedBufferSize
: audioTrackBufferSizeProvider.getBufferSizeInBytes(
getAudioTrackMinBufferSize(outputSampleRate, outputChannelConfig, outputEncoding),
outputEncoding,
outputMode,
outputPcmFrameSize,
outputSampleRate,
enableAudioTrackPlaybackParams ? MAX_PLAYBACK_SPEED : DEFAULT_PLAYBACK_SPEED);

if (outputEncoding == C.ENCODING_INVALID) {
throw new ConfigurationException(
Expand All @@ -736,8 +783,7 @@ public void configure(Format inputFormat, int specifiedBufferSize, @Nullable int
outputSampleRate,
outputChannelConfig,
outputEncoding,
specifiedBufferSize,
enableAudioTrackPlaybackParams,
bufferSize,
availableAudioProcessors);
if (isAudioTrackInitialized()) {
this.pendingConfiguration = pendingConfiguration;
Expand Down Expand Up @@ -1198,8 +1244,8 @@ public boolean hasPendingData() {
public void setPlaybackParameters(PlaybackParameters playbackParameters) {
playbackParameters =
new PlaybackParameters(
Util.constrainValue(playbackParameters.speed, MIN_PLAYBACK_SPEED, MAX_PLAYBACK_SPEED),
Util.constrainValue(playbackParameters.pitch, MIN_PITCH, MAX_PITCH));
constrainValue(playbackParameters.speed, MIN_PLAYBACK_SPEED, MAX_PLAYBACK_SPEED),
constrainValue(playbackParameters.pitch, MIN_PITCH, MAX_PITCH));
if (enableAudioTrackPlaybackParams && Util.SDK_INT >= 23) {
setAudioTrackPlaybackParametersV23(playbackParameters);
} else {
Expand Down Expand Up @@ -1780,47 +1826,6 @@ private static boolean isOffloadedPlayback(AudioTrack audioTrack) {
return Util.SDK_INT >= 29 && audioTrack.isOffloadedPlayback();
}

private static int getMaximumEncodedRateBytesPerSecond(@C.Encoding int encoding) {
switch (encoding) {
case C.ENCODING_MP3:
return MpegAudioUtil.MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_AAC_LC:
return AacUtil.AAC_LC_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_AAC_HE_V1:
return AacUtil.AAC_HE_V1_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_AAC_HE_V2:
return AacUtil.AAC_HE_V2_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_AAC_XHE:
return AacUtil.AAC_XHE_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_AAC_ELD:
return AacUtil.AAC_ELD_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_AC3:
return Ac3Util.AC3_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_E_AC3:
case C.ENCODING_E_AC3_JOC:
return Ac3Util.E_AC3_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_AC4:
return Ac4Util.MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_DTS:
return DtsUtil.DTS_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_DTS_HD:
return DtsUtil.DTS_HD_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_DOLBY_TRUEHD:
return Ac3Util.TRUEHD_MAX_RATE_BYTES_PER_SECOND;
case C.ENCODING_PCM_16BIT:
case C.ENCODING_PCM_16BIT_BIG_ENDIAN:
case C.ENCODING_PCM_24BIT:
case C.ENCODING_PCM_32BIT:
case C.ENCODING_PCM_8BIT:
case C.ENCODING_PCM_FLOAT:
case C.ENCODING_AAC_ER_BSAC:
case C.ENCODING_INVALID:
case Format.NO_VALUE:
default:
throw new IllegalArgumentException();
}
}

private static int getFramesPerEncodedSample(@C.Encoding int encoding, ByteBuffer buffer) {
switch (encoding) {
case C.ENCODING_MP3:
Expand Down Expand Up @@ -2010,6 +2015,13 @@ private static AudioFormat getAudioFormat(int sampleRate, int channelConfig, int
.build();
}

private static int getAudioTrackMinBufferSize(
int sampleRateInHz, int channelConfig, int encoding) {
int minBufferSize = AudioTrack.getMinBufferSize(sampleRateInHz, channelConfig, encoding);
Assertions.checkState(minBufferSize != AudioTrack.ERROR_BAD_VALUE);
return minBufferSize;
}

private final class PositionTrackerListener implements AudioTrackPositionTracker.Listener {

@Override
Expand Down Expand Up @@ -2104,8 +2116,7 @@ public Configuration(
int outputSampleRate,
int outputChannelConfig,
int outputEncoding,
int specifiedBufferSize,
boolean enableAudioTrackPlaybackParams,
int bufferSize,
AudioProcessor[] availableAudioProcessors) {
this.inputFormat = inputFormat;
this.inputPcmFrameSize = inputPcmFrameSize;
Expand All @@ -2114,10 +2125,8 @@ public Configuration(
this.outputSampleRate = outputSampleRate;
this.outputChannelConfig = outputChannelConfig;
this.outputEncoding = outputEncoding;
this.bufferSize = bufferSize;
this.availableAudioProcessors = availableAudioProcessors;

// Call computeBufferSize() last as it depends on the other configuration values.
this.bufferSize = computeBufferSize(specifiedBufferSize, enableAudioTrackPlaybackParams);
}

/** Returns if the configurations are sufficiently compatible to reuse the audio track. */
Expand All @@ -2137,10 +2146,6 @@ public long framesToDurationUs(long frameCount) {
return (frameCount * C.MICROS_PER_SECOND) / outputSampleRate;
}

public long durationUsToFrames(long durationUs) {
return (durationUs * outputSampleRate) / C.MICROS_PER_SECOND;
}

public AudioTrack buildAudioTrack(
boolean tunneling, AudioAttributes audioAttributes, int audioSessionId)
throws InitializationException {
Expand Down Expand Up @@ -2241,49 +2246,6 @@ private AudioTrack createAudioTrackV9(AudioAttributes audioAttributes, int audio
}
}

private int computeBufferSize(
int specifiedBufferSize, boolean enableAudioTrackPlaybackParameters) {
if (specifiedBufferSize != 0) {
return specifiedBufferSize;
}
switch (outputMode) {
case OUTPUT_MODE_PCM:
return getPcmDefaultBufferSize(
enableAudioTrackPlaybackParameters ? MAX_PLAYBACK_SPEED : DEFAULT_PLAYBACK_SPEED);
case OUTPUT_MODE_OFFLOAD:
return getEncodedDefaultBufferSize(OFFLOAD_BUFFER_DURATION_US);
case OUTPUT_MODE_PASSTHROUGH:
return getEncodedDefaultBufferSize(PASSTHROUGH_BUFFER_DURATION_US);
default:
throw new IllegalStateException();
}
}

private int getEncodedDefaultBufferSize(long bufferDurationUs) {
int rate = getMaximumEncodedRateBytesPerSecond(outputEncoding);
if (outputEncoding == C.ENCODING_AC3) {
rate *= AC3_BUFFER_MULTIPLICATION_FACTOR;
}
return (int) (bufferDurationUs * rate / C.MICROS_PER_SECOND);
}

private int getPcmDefaultBufferSize(float maxAudioTrackPlaybackSpeed) {
int minBufferSize =
AudioTrack.getMinBufferSize(outputSampleRate, outputChannelConfig, outputEncoding);
Assertions.checkState(minBufferSize != AudioTrack.ERROR_BAD_VALUE);
int multipliedBufferSize = minBufferSize * BUFFER_MULTIPLICATION_FACTOR;
int minAppBufferSize = (int) durationUsToFrames(MIN_BUFFER_DURATION_US) * outputPcmFrameSize;
int maxAppBufferSize =
max(minBufferSize, (int) durationUsToFrames(MAX_BUFFER_DURATION_US) * outputPcmFrameSize);
int bufferSize =
Util.constrainValue(multipliedBufferSize, minAppBufferSize, maxAppBufferSize);
if (maxAudioTrackPlaybackSpeed != 1f) {
// Maintain the buffer duration by scaling the size accordingly.
bufferSize = Math.round(bufferSize * maxAudioTrackPlaybackSpeed);
}
return bufferSize;
}

@RequiresApi(21)
private static android.media.AudioAttributes getAudioTrackAttributesV21(
AudioAttributes audioAttributes, boolean tunneling) {
Expand Down
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