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create stts box based on total duration of mediabox #1

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create stts box based on total duration of mediabox #1

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36 changes: 7 additions & 29 deletions libraries/muxer/src/main/java/androidx/media3/muxer/Boxes.java
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Original file line number Diff line number Diff line change
Expand Up @@ -655,40 +655,18 @@ public static List<Long> convertPresentationTimestampsToDurationsVu(
}

/** Generates the stts (decoding time to sample) box. */
public static ByteBuffer stts(List<Long> durationsVu) {
public static ByteBuffer stts(Long durationsVu,int writtenSampleSize) {
ByteBuffer contents =
ByteBuffer.allocate(durationsVu.size() * 8 + Mp4Utils.MAX_FIXED_LEAF_BOX_SIZE);
ByteBuffer.allocate(Long.BYTES + Mp4Utils.MAX_FIXED_LEAF_BOX_SIZE);

int sampleDelta = writtenSampleSize == 0 ? 0 : durationsVu.intValue()/writtenSampleSize;

contents.putInt(0x0); // version and flags.

// We will know total entry count only after processing all the sample durations, so put in a
// placeholder for total entry count and store its index.
int totalEntryCountIndex = contents.position();
contents.putInt(0x0); // entry_count.

int totalEntryCount = 0;
long lastDurationVu = -1L;
int lastSampleCountIndex = -1;

// Note that the framework MediaMuxer adjust time deltas within plus-minus 100 us, so that
// samples have repeating duration values. It saves few entries in the table.
for (int i = 0; i < durationsVu.size(); i++) {
long durationVu = durationsVu.get(i);
if (lastDurationVu != durationVu) {
lastDurationVu = durationVu;
lastSampleCountIndex = contents.position();

// sample_count; this will be updated instead of adding a new entry if the next sample has
// the same duration.
contents.putInt(1);
contents.putInt((int) durationVu); // sample_delta.
totalEntryCount++;
} else {
contents.putInt(lastSampleCountIndex, contents.getInt(lastSampleCountIndex) + 1);
}
}
contents.putInt(1); // entry_count.
contents.putInt(writtenSampleSize);
contents.putInt(sampleDelta);

contents.putInt(totalEntryCountIndex, totalEntryCount);

contents.flip();
return BoxUtils.wrapIntoBox("stts", contents);
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2 changes: 1 addition & 1 deletion libraries/muxer/src/main/java/androidx/media3/muxer/Mp4MoovStructure.java
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Expand Up @@ -96,7 +96,7 @@ public ByteBuffer moovMetadataHeader(
Mp4Utils.usFromVu(trackDurationInTrackUnitsVu, track.videoUnitTimebase());

@C.TrackType int trackType = MimeTypes.getTrackType(format.sampleMimeType);
ByteBuffer stts = Boxes.stts(sampleDurationsVu);
ByteBuffer stts = Boxes.stts(trackDurationInTrackUnitsVu,track.writtenSamples().size());
ByteBuffer stsz = Boxes.stsz(track.writtenSamples());
ByteBuffer stsc = Boxes.stsc(track.writtenChunkSampleCounts());
ByteBuffer chunkOffsetBox =
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21 changes: 18 additions & 3 deletions libraries/muxer/src/test/java/androidx/media3/muxer/BoxesTest.java
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Expand Up @@ -442,7 +442,12 @@ public void createVideoSampleEntryBox_withUnknownVideoFormat_throws() {
public void createSttsBox_withSingleSampleDuration_matchesExpected() throws IOException {
ImmutableList<Long> sampleDurations = ImmutableList.of(500L);

ByteBuffer sttsBox = Boxes.stts(sampleDurations);
Long totalDuration = 0L;
for (int i = 0; i < sampleDurations.size(); i++) {
totalDuration += sampleDurations.get(i);
}
ByteBuffer sttsBox = Boxes.stts(totalDuration,sampleDurations.size());


DumpableMp4Box dumpableBox = new DumpableMp4Box(sttsBox);
DumpFileAsserts.assertOutput(
Expand All @@ -455,7 +460,12 @@ public void createSttsBox_withSingleSampleDuration_matchesExpected() throws IOEx
public void createSttsBox_withAllDifferentSampleDurations_matchesExpected() throws IOException {
ImmutableList<Long> sampleDurations = ImmutableList.of(1_000L, 2_000L, 3_000L, 5_000L);

ByteBuffer sttsBox = Boxes.stts(sampleDurations);
Long totalDuration = 0L;
for (int i = 0; i < sampleDurations.size(); i++) {
totalDuration += sampleDurations.get(i);
}
ByteBuffer sttsBox = Boxes.stts(totalDuration,sampleDurations.size());


DumpableMp4Box dumpableBox = new DumpableMp4Box(sttsBox);
DumpFileAsserts.assertOutput(
Expand All @@ -469,7 +479,12 @@ public void createSttsBox_withFewConsecutiveSameSampleDurations_matchesExpected(
throws IOException {
ImmutableList<Long> sampleDurations = ImmutableList.of(1_000L, 2_000L, 2_000L, 2_000L);

ByteBuffer sttsBox = Boxes.stts(sampleDurations);
Long totalDuration = 0L;
for (int i = 0; i < sampleDurations.size(); i++) {
totalDuration += sampleDurations.get(i);
}
ByteBuffer sttsBox = Boxes.stts(totalDuration,sampleDurations.size());


DumpableMp4Box dumpableBox = new DumpableMp4Box(sttsBox);
DumpFileAsserts.assertOutput(
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