diff options
Diffstat (limited to 'mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/SilenceMediaSource.java')
| -rw-r--r-- | mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/SilenceMediaSource.java | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/SilenceMediaSource.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/SilenceMediaSource.java new file mode 100644 index 0000000000..096cc66622 --- /dev/null +++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/SilenceMediaSource.java @@ -0,0 +1,253 @@ +/* + * Copyright (C) 2019 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.mozilla.thirdparty.com.google.android.exoplayer2.source; + +import androidx.annotation.Nullable; +import org.mozilla.thirdparty.com.google.android.exoplayer2.C; +import org.mozilla.thirdparty.com.google.android.exoplayer2.Format; +import org.mozilla.thirdparty.com.google.android.exoplayer2.FormatHolder; +import org.mozilla.thirdparty.com.google.android.exoplayer2.SeekParameters; +import org.mozilla.thirdparty.com.google.android.exoplayer2.decoder.DecoderInputBuffer; +import org.mozilla.thirdparty.com.google.android.exoplayer2.trackselection.TrackSelection; +import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.Allocator; +import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.TransferListener; +import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions; +import org.mozilla.thirdparty.com.google.android.exoplayer2.util.MimeTypes; +import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util; +import java.util.ArrayList; +import org.checkerframework.checker.nullness.compatqual.NullableType; + +/** Media source with a single period consisting of silent raw audio of a given duration. */ +public final class SilenceMediaSource extends BaseMediaSource { + + private static final int SAMPLE_RATE_HZ = 44100; + @C.PcmEncoding private static final int ENCODING = C.ENCODING_PCM_16BIT; + private static final int CHANNEL_COUNT = 2; + private static final Format FORMAT = + Format.createAudioSampleFormat( + /* id=*/ null, + MimeTypes.AUDIO_RAW, + /* codecs= */ null, + /* bitrate= */ Format.NO_VALUE, + /* maxInputSize= */ Format.NO_VALUE, + CHANNEL_COUNT, + SAMPLE_RATE_HZ, + ENCODING, + /* initializationData= */ null, + /* drmInitData= */ null, + /* selectionFlags= */ 0, + /* language= */ null); + private static final byte[] SILENCE_SAMPLE = + new byte[Util.getPcmFrameSize(ENCODING, CHANNEL_COUNT) * 1024]; + + private final long durationUs; + + /** + * Creates a new media source providing silent audio of the given duration. + * + * @param durationUs The duration of silent audio to output, in microseconds. + */ + public SilenceMediaSource(long durationUs) { + Assertions.checkArgument(durationUs >= 0); + this.durationUs = durationUs; + } + + @Override + protected void prepareSourceInternal(@Nullable TransferListener mediaTransferListener) { + refreshSourceInfo( + new SinglePeriodTimeline( + durationUs, /* isSeekable= */ true, /* isDynamic= */ false, /* isLive= */ false)); + } + + @Override + public void maybeThrowSourceInfoRefreshError() {} + + @Override + public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) { + return new SilenceMediaPeriod(durationUs); + } + + @Override + public void releasePeriod(MediaPeriod mediaPeriod) {} + + @Override + protected void releaseSourceInternal() {} + + private static final class SilenceMediaPeriod implements MediaPeriod { + + private static final TrackGroupArray TRACKS = new TrackGroupArray(new TrackGroup(FORMAT)); + + private final long durationUs; + private final ArrayList<SampleStream> sampleStreams; + + public SilenceMediaPeriod(long durationUs) { + this.durationUs = durationUs; + sampleStreams = new ArrayList<>(); + } + + @Override + public void prepare(Callback callback, long positionUs) { + callback.onPrepared(/* mediaPeriod= */ this); + } + + @Override + public void maybeThrowPrepareError() {} + + @Override + public TrackGroupArray getTrackGroups() { + return TRACKS; + } + + @Override + public long selectTracks( + @NullableType TrackSelection[] selections, + boolean[] mayRetainStreamFlags, + @NullableType SampleStream[] streams, + boolean[] streamResetFlags, + long positionUs) { + positionUs = constrainSeekPosition(positionUs); + for (int i = 0; i < selections.length; i++) { + if (streams[i] != null && (selections[i] == null || !mayRetainStreamFlags[i])) { + sampleStreams.remove(streams[i]); + streams[i] = null; + } + if (streams[i] == null && selections[i] != null) { + SilenceSampleStream stream = new SilenceSampleStream(durationUs); + stream.seekTo(positionUs); + sampleStreams.add(stream); + streams[i] = stream; + streamResetFlags[i] = true; + } + } + return positionUs; + } + + @Override + public void discardBuffer(long positionUs, boolean toKeyframe) {} + + @Override + public long readDiscontinuity() { + return C.TIME_UNSET; + } + + @Override + public long seekToUs(long positionUs) { + positionUs = constrainSeekPosition(positionUs); + for (int i = 0; i < sampleStreams.size(); i++) { + ((SilenceSampleStream) sampleStreams.get(i)).seekTo(positionUs); + } + return positionUs; + } + + @Override + public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) { + return constrainSeekPosition(positionUs); + } + + @Override + public long getBufferedPositionUs() { + return C.TIME_END_OF_SOURCE; + } + + @Override + public long getNextLoadPositionUs() { + return C.TIME_END_OF_SOURCE; + } + + @Override + public boolean continueLoading(long positionUs) { + return false; + } + + @Override + public boolean isLoading() { + return false; + } + + @Override + public void reevaluateBuffer(long positionUs) {} + + private long constrainSeekPosition(long positionUs) { + return Util.constrainValue(positionUs, 0, durationUs); + } + } + + private static final class SilenceSampleStream implements SampleStream { + + private final long durationBytes; + + private boolean sentFormat; + private long positionBytes; + + public SilenceSampleStream(long durationUs) { + durationBytes = getAudioByteCount(durationUs); + seekTo(0); + } + + public void seekTo(long positionUs) { + positionBytes = Util.constrainValue(getAudioByteCount(positionUs), 0, durationBytes); + } + + @Override + public boolean isReady() { + return true; + } + + @Override + public void maybeThrowError() {} + + @Override + public int readData( + FormatHolder formatHolder, DecoderInputBuffer buffer, boolean formatRequired) { + if (!sentFormat || formatRequired) { + formatHolder.format = FORMAT; + sentFormat = true; + return C.RESULT_FORMAT_READ; + } + + long bytesRemaining = durationBytes - positionBytes; + if (bytesRemaining == 0) { + buffer.addFlag(C.BUFFER_FLAG_END_OF_STREAM); + return C.RESULT_BUFFER_READ; + } + + int bytesToWrite = (int) Math.min(SILENCE_SAMPLE.length, bytesRemaining); + buffer.ensureSpaceForWrite(bytesToWrite); + buffer.data.put(SILENCE_SAMPLE, /* offset= */ 0, bytesToWrite); + buffer.timeUs = getAudioPositionUs(positionBytes); + buffer.addFlag(C.BUFFER_FLAG_KEY_FRAME); + positionBytes += bytesToWrite; + return C.RESULT_BUFFER_READ; + } + + @Override + public int skipData(long positionUs) { + long oldPositionBytes = positionBytes; + seekTo(positionUs); + return (int) ((positionBytes - oldPositionBytes) / SILENCE_SAMPLE.length); + } + } + + private static long getAudioByteCount(long durationUs) { + long audioSampleCount = durationUs * SAMPLE_RATE_HZ / C.MICROS_PER_SECOND; + return Util.getPcmFrameSize(ENCODING, CHANNEL_COUNT) * audioSampleCount; + } + + private static long getAudioPositionUs(long bytes) { + long audioSampleCount = bytes / Util.getPcmFrameSize(ENCODING, CHANNEL_COUNT); + return audioSampleCount * C.MICROS_PER_SECOND / SAMPLE_RATE_HZ; + } +} |