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Calculate min timestamp across tracks in the Boxes.moov method

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The Boxes.moov method can do the calculation instead of caller doing
it.

PiperOrigin-RevId: 679653033
This commit is contained in:
sheenachhabra 2024-09-27 10:58:04 -07:00 committed by Copybara-Service
parent 4481b3567e
commit b0b54ca018
3 changed files with 25 additions and 36 deletions
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23
libraries/muxer/src/main/java/androidx/media3/muxer/Boxes.java
View File

@ -22,6 +22,7 @@ import static androidx.media3.muxer.ColorUtils.MEDIAFORMAT_STANDARD_TO_PRIMARIES
import static androidx.media3.muxer.ColorUtils.MEDIAFORMAT_TRANSFER_TO_MP4_TRANSFER;
import static androidx.media3.muxer.MuxerUtil.UNSIGNED_INT_MAX_VALUE;
import static java.lang.Math.max;
import static java.lang.Math.min;
import static java.nio.charset.StandardCharsets.UTF_8;
import android.media.MediaCodec;
@ -118,7 +119,6 @@ import org.checkerframework.checker.nullness.qual.PolyNull;
public static ByteBuffer moov(
List<Track> tracks,
MetadataCollector metadataCollector,
long minInputPtsUs,
boolean isFragmentedMp4,
@Mp4Muxer.LastSampleDurationBehavior int lastSampleDurationBehavior) {
// The timestamp will always fit into a 32-bit integer. This is already validated in the
@ -127,6 +127,15 @@ import org.checkerframework.checker.nullness.qual.PolyNull;
int creationTimestampSeconds = (int) metadataCollector.timestampData.creationTimestampSeconds;
int modificationTimestampSeconds =
(int) metadataCollector.timestampData.modificationTimestampSeconds;
long minInputPtsUs = findMinimumPresentationTimestampUsAcrossTracks(tracks);
// For a non fragmented MP4 file, avoid writing an empty moov box.
// For a fragmented MP4 file, the minInputPtsUs gets ignored as the moov box is written without
// any sample info.
if (!isFragmentedMp4 && minInputPtsUs == C.TIME_UNSET) {
return ByteBuffer.allocate(0);
}
List<ByteBuffer> trakBoxes = new ArrayList<>();
List<ByteBuffer> trexBoxes = new ArrayList<>();
@ -134,6 +143,7 @@ import org.checkerframework.checker.nullness.qual.PolyNull;
long videoDurationUs = 0L;
for (int i = 0; i < tracks.size(); i++) {
Track track = tracks.get(i);
// For a non fragmented MP4 file, avoid writing an empty track.
if (!isFragmentedMp4 && track.writtenSamples.isEmpty()) {
continue;
}
@ -1830,4 +1840,15 @@ import org.checkerframework.checker.nullness.qual.PolyNull;
return Util.scaleLargeValue(
timestampUs, videoUnitTimebase, C.MICROS_PER_SECOND, RoundingMode.HALF_UP);
}
private static long findMinimumPresentationTimestampUsAcrossTracks(List<Track> tracks) {
long minInputPtsUs = Long.MAX_VALUE;
for (int i = 0; i < tracks.size(); i++) {
Track track = tracks.get(i);
if (!track.writtenSamples.isEmpty()) {
minInputPtsUs = min(track.writtenSamples.get(0).presentationTimeUs, minInputPtsUs);
}
}
return minInputPtsUs != Long.MAX_VALUE ? minInputPtsUs : C.TIME_UNSET;
}
}

7
libraries/muxer/src/main/java/androidx/media3/muxer/FragmentedMp4Writer.java
View File

@ -202,14 +202,9 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
private void createHeader() throws IOException {
output.position(0L);
output.write(Boxes.ftyp());
// The minInputPtsUs is actually ignored as there are no pending samples to write.
output.write(
Boxes.moov(
tracks,
metadataCollector,
/* minInputPtsUs= */ 0L,
/* isFragmentedMp4= */ true,
lastSampleDurationBehavior));
tracks, metadataCollector, /* isFragmentedMp4= */ true, lastSampleDurationBehavior));
}
private boolean shouldFlushPendingSamples(

31
libraries/muxer/src/main/java/androidx/media3/muxer/Mp4Writer.java
View File

@ -202,7 +202,6 @@ import java.util.concurrent.atomic.AtomicBoolean;
Boxes.moov(
editableVideoTracks,
editableVideoMetadataCollector,
findMinimumPresentationTimestampUsAcrossTracks(editableVideoTracks),
/* isFragmentedMp4= */ false,
lastSampleDurationBehavior);
ByteBuffer edvdBoxHeader =
@ -273,17 +272,6 @@ import java.util.concurrent.atomic.AtomicBoolean;
outputFileChannel.truncate(newMoovLocation + moovBytesNeeded);
}
private static long findMinimumPresentationTimestampUsAcrossTracks(List<Track> tracks) {
long minInputPtsUs = Long.MAX_VALUE;
for (int i = 0; i < tracks.size(); i++) {
Track track = tracks.get(i);
if (!track.writtenSamples.isEmpty()) {
minInputPtsUs = min(track.writtenSamples.get(0).presentationTimeUs, minInputPtsUs);
}
}
return minInputPtsUs;
}
private void writeHeader() throws IOException {
outputFileChannel.position(0L);
outputFileChannel.write(Boxes.ftyp());
@ -311,24 +299,9 @@ import java.util.concurrent.atomic.AtomicBoolean;
}
private ByteBuffer assembleCurrentMoovData() {
// Recalculate the min timestamp every time, in case some new samples have smaller timestamps.
long minInputPtsUs = findMinimumPresentationTimestampUsAcrossTracks(tracks);
ByteBuffer moovHeader;
if (minInputPtsUs != Long.MAX_VALUE) {
moovHeader =
Boxes.moov(
tracks,
metadataCollector,
minInputPtsUs,
/* isFragmentedMp4= */ false,
lastSampleDurationBehavior);
} else {
// Skip moov box, if there are no samples.
moovHeader = ByteBuffer.allocate(0);
}
return moovHeader;
return Boxes.moov(
tracks, metadataCollector, /* isFragmentedMp4= */ false, lastSampleDurationBehavior);
}
/**