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Do not trim audio samples by changing their timestamp

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MP4 edit lists sometimes ask to start playback between two samples.
If this happens, we currently change the timestamp of the first
sample to zero to trim it (e.g. to display the first frame for a
slightly shorter period of time). However, we can't do this to audio
samples are they have an inherent duration and trimming them this
way is not possible.

PiperOrigin-RevId: 543420218
(cherry picked from commit 2322462404)
This commit is contained in:
tonihei 2023-06-26 13:26:35 +00:00 committed by Tianyi Feng
parent bf4561c606
commit ec13c42800
3 changed files with 12 additions and 3 deletions
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11
libraries/extractor/src/main/java/androidx/media3/extractor/mp4/AtomParsers.java
View file

@ -775,7 +775,10 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
long ptsUs = Util.scaleLargeTimestamp(pts, C.MICROS_PER_SECOND, track.movieTimescale);
long timeInSegmentUs =
Util.scaleLargeTimestamp(
max(0, timestamps[j] - editMediaTime), C.MICROS_PER_SECOND, track.timescale);
timestamps[j] - editMediaTime, C.MICROS_PER_SECOND, track.timescale);
if (canTrimSamplesWithTimestampChange(track.type)) {
timeInSegmentUs = max(0, timeInSegmentUs);
}
editedTimestamps[sampleIndex] = ptsUs + timeInSegmentUs;
if (copyMetadata && editedSizes[sampleIndex] > editedMaximumSize) {
editedMaximumSize = sizes[j];
@ -796,6 +799,12 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
editedDurationUs);
}
private static boolean canTrimSamplesWithTimestampChange(@C.TrackType int trackType) {
// Audio samples have an inherent duration and we can't trim data by changing the sample
// timestamp alone.
return trackType != C.TRACK_TYPE_AUDIO;
}
@Nullable
private static Metadata parseUdtaMeta(ParsableByteArray meta, int limit) {
meta.skipBytes(Atom.HEADER_SIZE);

2
libraries/test_data/src/test/assets/extractordumps/mp4/sample_opus.mp4.0.dump
View file

@ -22,7 +22,7 @@ track 0:
data = length 8, hash 72CBCBF5
data = length 8, hash 79C07075
sample 0:
time = 0
time = -6500
flags = 1
data = length 3, hash 4732
sample 1:

2
libraries/test_data/src/test/assets/extractordumps/mp4/sample_opus.mp4.unknown_length.dump
View file

@ -22,7 +22,7 @@ track 0:
data = length 8, hash 72CBCBF5
data = length 8, hash 79C07075
sample 0:
time = 0
time = -6500
flags = 1
data = length 3, hash 4732
sample 1: