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Tweak SubtitleTranscodingTrackOutput.ensureSampleDataCapacity

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This more closely matches the intended, documented behaviour of this
method. The previous implementation was incorrectly checking
`sampleDataEnd + newSampleSize`, but it's more correct to compare
`existingSampleDataLength + newSampleSize`, in order to handle the
case of non-zero `sampleDataStart`. We've already checked above whether
`newSampleSize` fits after `sampleDataEnd` without growing or
reshuffling the array, so no need to basically repeat that check.

In the case of handling one sample at a time, the previous
implementation resulted in `sampleData` growing by `sampleSize`
**every time** the pointers reached the end. With the new check for
`sampleDataStart == sampleDataEnd`, this is avoided by always writing
each new sample at the start of the array (because the previous sample
has already been consumed), meaning `sampleData` remains equal to
`sampleSize` without growing.

PiperOrigin-RevId: 593119927
This commit is contained in:
ibaker 2023-12-22 08:03:49 -08:00 committed by Copybara-Service
parent 7e12b9e15f
commit 64231ee079
1 changed files with 9 additions and 2 deletions
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11
libraries/extractor/src/main/java/androidx/media3/extractor/text/SubtitleTranscodingTrackOutput.java
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@ -20,7 +20,6 @@ import static androidx.media3.common.util.Assertions.checkArgument;
import static androidx.media3.common.util.Assertions.checkNotNull;
import static androidx.media3.common.util.Assertions.checkState;
import static androidx.media3.common.util.Assertions.checkStateNotNull;
import static java.lang.Math.max;
import androidx.annotation.Nullable;
import androidx.media3.common.C;
@ -151,6 +150,11 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
SubtitleParser.OutputOptions.allCues(),
cuesWithTiming -> outputSample(cuesWithTiming, timeUs, flags));
sampleDataStart = sampleStart + size;
if (sampleDataStart == sampleDataEnd) {
// The array is now empty, so we can move the start and end pointers back to the start.
sampleDataStart = 0;
sampleDataEnd = 0;
}
}
// Clearing deprecated decode-only flag for compatibility with decoders that are still using it.
@ -194,7 +198,10 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
return;
}
int existingSampleDataLength = sampleDataEnd - sampleDataStart;
int targetLength = max(existingSampleDataLength * 2, sampleDataEnd + newSampleSize);
// Make sure there's enough space for the new sample (after we move existing data to the
// beginning of the array).
int targetLength =
Math.max(existingSampleDataLength * 2, existingSampleDataLength + newSampleSize);
byte[] newSampleData = targetLength <= sampleData.length ? sampleData : new byte[targetLength];
System.arraycopy(sampleData, sampleDataStart, newSampleData, 0, existingSampleDataLength);
sampleDataStart = 0;