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Support variable length sgpd boxes in fMPEG #3178

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Support variable length sgpd boxes in fMPEG #3178

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2c7ae96
Support variable length `sgpd` boxes in fMPEG
dimitry-unified-streaming Apr 20, 2026
2c0a948
Add test with a variable length sgpd box in a fragmented MP4 file.
dimitry-unified-streaming May 19, 2026
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11 changes: 5 additions & 6 deletions libraries/extractor/src/main/java/androidx/media3/extractor/mp4/FragmentedMp4Extractor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1479,18 +1479,17 @@ private static void parseSampleGroups(
sgpd.setPosition(Mp4Box.HEADER_SIZE);
int sgpdVersion = BoxParser.parseFullBoxVersion(sgpd.readInt());
sgpd.skipBytes(4); // grouping_type == seig.
if (sgpdVersion == 1) {
if (sgpd.readUnsignedInt() == 0) {
throw ParserException.createForUnsupportedContainerFeature(
"Variable length description in sgpd found (unsupported)");
}
} else if (sgpdVersion >= 2) {
long default_length = sgpdVersion >= 1 ? sgpd.readUnsignedInt() : 0;
if (sgpdVersion >= 2) {
sgpd.skipBytes(4); // default_sample_description_index.
}
if (sgpd.readUnsignedInt() != 1) { // entry_count.
throw ParserException.createForUnsupportedContainerFeature(
"Entry count in sgpd != 1 (unsupported).");
}
if (sgpdVersion >= 1 && default_length == 0) {
sgpd.skipBytes(4); // description_length.
}

// CencSampleEncryptionInformationGroupEntry
sgpd.skipBytes(1); // reserved = 0.
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16 changes: 16 additions & 0 deletions ...c/test/java/androidx/media3/extractor/mp4/FragmentedMp4ExtractorNonParameterizedTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,22 @@ public void sniff_returnsFalseWithoutPeekingLargeStbl() throws Exception {
assertThat(input.getMaxPeekLimit()).isLessThan(500);
}

@Test
public void extract_h264WithVariableLengthSgpdBox() throws Exception {
FragmentedMp4Extractor extractor =
new FragmentedMp4Extractor(SubtitleParser.Factory.UNSUPPORTED);
FakeExtractorOutput output =
TestUtil.extractAllSamplesFromFile(
extractor,
ApplicationProvider.getApplicationContext(),
"media/mp4/sample_fragmented_variable_length_sgpd.mp4");

DumpFileAsserts.assertOutput(
ApplicationProvider.getApplicationContext(),
output,
"extractordumps/mp4/fragmented_variable_length_sgpd.mp4");
}

private static FakeExtractorInput createInputForSample(String sample) throws IOException {
return new FakeExtractorInput.Builder()
.setData(
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