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Avoid time discontinuity when retrying a live stream.

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Issue: #227
Issue: #389
This commit is contained in:
Oliver Woodman 2015-04-17 20:12:11 +01:00
parent faf0e2c147
commit 55e08ff712
1 changed files with 38 additions and 11 deletions
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49
library/src/main/java/com/google/android/exoplayer/extractor/ExtractorSampleSource.java
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@ -80,6 +80,10 @@ public class ExtractorSampleSource implements SampleSource, ExtractorOutput, Loa
private long lastSeekPositionUs;
private long pendingResetPositionUs;
private boolean havePendingNextSampleUs;
private long pendingNextSampleUs;
private long sampleTimeOffsetUs;
private Loader loader;
private ExtractingLoadable loadable;
private IOException currentLoadableException;
@ -235,6 +239,12 @@ public class ExtractorSampleSource implements SampleSource, ExtractorOutput, Loa
if (sampleQueue.getSample(sampleHolder)) {
boolean decodeOnly = frameAccurateSeeking && sampleHolder.timeUs < lastSeekPositionUs;
sampleHolder.flags |= decodeOnly ? C.SAMPLE_FLAG_DECODE_ONLY : 0;
if (havePendingNextSampleUs) {
// Set the offset to make the timestamp of this sample equal to pendingNextSampleUs.
sampleTimeOffsetUs = pendingNextSampleUs - sampleHolder.timeUs;
havePendingNextSampleUs = false;
}
sampleHolder.timeUs += sampleTimeOffsetUs;
return SAMPLE_READ;
}
@ -392,16 +402,27 @@ public class ExtractorSampleSource implements SampleSource, ExtractorOutput, Loa
long elapsedMillis = SystemClock.elapsedRealtime() - currentLoadableExceptionTimestamp;
if (elapsedMillis >= getRetryDelayMillis(currentLoadableExceptionCount)) {
currentLoadableException = null;
if (!prepared || !seekMap.isSeekable()) {
// One of two cases applies:
// 1. We're not prepared. We don't know whether we're playing an on-demand or a live
// stream. Play it safe and start from scratch.
// 2. We're playing a non-seekable stream. Assume it's a live stream. In such cases it's
// best to discard the pending buffer and start from scratch.
if (!prepared) {
// We don't know whether we're playing an on-demand or a live stream. For a live stream
// we need to load from the start, as outlined below. Since we might be playing a live
// stream, play it safe and load from the start.
for (int i = 0; i < sampleQueues.size(); i++) {
sampleQueues.valueAt(i).clear();
}
loadable = createPreparationLoadable();
loadable = createLoadableFromStart();
} else if (!seekMap.isSeekable()) {
// We're playing a non-seekable stream. Assume it's live, and therefore that the data at
// the uri is a continuously shifting window of the latest available media. For this case
// there's no way to continue loading from where a previous load finished, and hence it's
// necessary to load from the start whenever commencing a new load.
for (int i = 0; i < sampleQueues.size(); i++) {
sampleQueues.valueAt(i).clear();
}
loadable = createLoadableFromStart();
// To avoid introducing a discontinuity, we shift the sample timestamps so that they will
// continue from the current downstream position.
pendingNextSampleUs = downstreamPositionUs;
havePendingNextSampleUs = true;
} else {
// We're playing a seekable on-demand stream. Resume the current loadable, which will
// request data starting from the point it left off.
@ -411,11 +432,17 @@ public class ExtractorSampleSource implements SampleSource, ExtractorOutput, Loa
return;
}
// We're not retrying, so we're either starting a playback or responding to an explicit seek.
// In both cases sampleTimeOffsetUs should be reset to zero, and any pending adjustment to
// sample timestamps should be discarded.
sampleTimeOffsetUs = 0;
havePendingNextSampleUs = false;
if (!prepared) {
loadable = createPreparationLoadable();
loadable = createLoadableFromStart();
} else {
Assertions.checkState(isPendingReset());
loadable = createLoadableForPosition(pendingResetPositionUs);
loadable = createLoadableFromPositionUs(pendingResetPositionUs);
pendingResetPositionUs = NO_RESET_PENDING;
}
loader.startLoading(loadable, this);
@ -441,11 +468,11 @@ public class ExtractorSampleSource implements SampleSource, ExtractorOutput, Loa
}
}
private ExtractingLoadable createPreparationLoadable() {
private ExtractingLoadable createLoadableFromStart() {
return new ExtractingLoadable(uri, dataSource, extractor, bufferPool, requestedBufferSize, 0);
}
private ExtractingLoadable createLoadableForPosition(long positionUs) {
private ExtractingLoadable createLoadableFromPositionUs(long positionUs) {
return new ExtractingLoadable(uri, dataSource, extractor, bufferPool, requestedBufferSize,
seekMap.getPosition(positionUs));
}