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@rohitjoins
rohitjoins committed Nov 29, 2023
1 parent 2c3eac4 commit 3adabe8
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Showing 2 changed files with 74 additions and 59 deletions.
117 changes: 59 additions & 58 deletions libraries/extractor/src/main/java/androidx/media3/extractor/ts/AdtsReader.java
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Original file line number Diff line number Diff line change
Expand Up @@ -574,78 +574,79 @@ private void parseAdtsHeader() throws ParserException {
}

@RequiresNonNull("currentOutput")
void readAacProgramConfigElement() {
Format pendingOutputFormat = checkNotNull(this.pendingOutputFormat);
private void readAacProgramConfigElement() throws ParserException {
ParsableBitArray pceBuffer = checkNotNull(this.pceBuffer);

// See ISO 13818-7 Advanced Audio Coding (2006) Table 36 for PCE tag encoding.
if (pceBuffer.readBits(3) == 5 /* PCE tag */) {
// See ISO 13818-7 Advanced Audio Coding (2006) Table 25 for syntax of a PCE.
pceBuffer.skipBits(10); // element_instance_tag(4), profile(2), element_instance_tag(4)

int channelBits = 0;
// num_front_channel_elements, front_element_is_cpe(1), front_element_tag_select(4)
channelBits += pceBuffer.readBits(4) * 5;
// num_side_channel_elements, side_element_is_cpe(1), side_element_tag_select(4)
channelBits += pceBuffer.readBits(4) * 5;
// num_back_channel_elements, back_element_is_cpe(1), back_element_tag_select(4)
channelBits += pceBuffer.readBits(4) * 5;
// num_lfe_channel_elements, lfe_element_tag_select(4)
channelBits += pceBuffer.readBits(2) * 4;
// num_assoc_data_elements, assoc_data_element_tag_select(4)
channelBits += pceBuffer.readBits(3) * 4;
// num_valid_cc_elements, cc_element_is_ind_sw(1), valid_cc_element_tag_select(4)
channelBits += pceBuffer.readBits(4) * 5;

if (pceBuffer.readBit()) { // mono_mixdown_present
pceBuffer.skipBits(4); // mono_mixdown_element_number
}
if (pceBuffer.readBits(3) != 5 /* PCE tag */) {
throw ParserException.createForMalformedContainer(/* message= */ null, /* cause= */ null);
}

if (pceBuffer.readBit()) { // stereo_mixdown_present
pceBuffer.skipBits(4); // stereo_mixdown_element_number
}
// See ISO 13818-7 Advanced Audio Coding (2006) Table 25 for syntax of a PCE.
pceBuffer.skipBits(10); // element_instance_tag(4), profile(2), element_instance_tag(4)

int channelBits = 0;
// num_front_channel_elements, front_element_is_cpe(1), front_element_tag_select(4)
channelBits += pceBuffer.readBits(4) * 5;
// num_side_channel_elements, side_element_is_cpe(1), side_element_tag_select(4)
channelBits += pceBuffer.readBits(4) * 5;
// num_back_channel_elements, back_element_is_cpe(1), back_element_tag_select(4)
channelBits += pceBuffer.readBits(4) * 5;
// num_lfe_channel_elements, lfe_element_tag_select(4)
channelBits += pceBuffer.readBits(2) * 4;
// num_assoc_data_elements, assoc_data_element_tag_select(4)
channelBits += pceBuffer.readBits(3) * 4;
// num_valid_cc_elements, cc_element_is_ind_sw(1), valid_cc_element_tag_select(4)
channelBits += pceBuffer.readBits(4) * 5;

if (pceBuffer.readBit()) { // mono_mixdown_present
pceBuffer.skipBits(4); // mono_mixdown_element_number
}

if (pceBuffer.readBit()) { // matrix_mixdown_idx_present
pceBuffer.skipBits(3); // matrix_mixdown_idx(2), matrix_mixdown_idx(1)
}
if (pceBuffer.readBit()) { // stereo_mixdown_present
pceBuffer.skipBits(4); // stereo_mixdown_element_number
}

int numAlignmentBits =
8 - (pceBuffer.getPosition() + channelBits + 7) % 8 - 1; // byte_alignment
int commentSizeBits = 8; // comment_field_bytes
if (pceBuffer.readBit()) { // matrix_mixdown_idx_present
pceBuffer.skipBits(3); // matrix_mixdown_idx(2), matrix_mixdown_idx(1)
}

// Beyond this point, pceBuffer may be empty, so check before consuming.
if (pceBuffer.bitsLeft() >= channelBits + numAlignmentBits + commentSizeBits) {
pceBuffer.skipBits(channelBits);
int numAlignmentBits =
8 - (pceBuffer.getPosition() + channelBits + 7) % 8 - 1; // byte_alignment
int commentSizeBits = 8; // comment_field_bytes

// Store PCE size excluding initial PCE tag, alignment bits and comment for later.
int numPceBits = pceBuffer.getPosition() - 3 /* PCE tag */;
// Beyond this point, pceBuffer may be empty, so check before consuming.
if (pceBuffer.bitsLeft() < channelBits + numAlignmentBits + commentSizeBits) {
throw ParserException.createForMalformedContainer(/* message= */ null, /* cause= */ null);
}

pceBuffer.skipBits(numAlignmentBits);
int commentSize = pceBuffer.readBits(commentSizeBits);
pceBuffer.skipBits(channelBits);

if (sampleSize >= pceBuffer.getBytePosition() + commentSize) {
// Append PCE to format's audio specific config.
byte[] oldConfig = pendingOutputFormat.initializationData.get(0);
// Store PCE size excluding initial PCE tag, alignment bits and comment for later.
int numPceBits = pceBuffer.getPosition() - 3 /* PCE tag */;
pceBuffer.skipBits(numAlignmentBits);
int commentSize = pceBuffer.readBits(commentSizeBits);

int configSize = oldConfig.length;
configSize += (numPceBits + 7) / 8 + 1; // Byte align and add a zero length comment.
byte[] newConfig = Arrays.copyOf(oldConfig, configSize);
if (sampleSize < pceBuffer.getBytePosition() + commentSize) {
throw ParserException.createForMalformedContainer(/* message= */ null, /* cause= */ null);
}

pceBuffer.setPosition(3 /* PCE tag */);
pceBuffer.readBits(newConfig, oldConfig.length, numPceBits);
Format pendingOutputFormat = checkNotNull(this.pendingOutputFormat);
// Append PCE to format's audio specific config.
byte[] oldConfig = pendingOutputFormat.initializationData.get(0);
int configSize = oldConfig.length;
configSize += (numPceBits + 7) / 8 + 1; // Byte align and add a zero length comment.
byte[] newConfig = Arrays.copyOf(oldConfig, configSize);

pendingOutputFormat =
pendingOutputFormat
.buildUpon()
.setInitializationData(ImmutableList.of(newConfig))
.build();
pceBuffer.setPosition(3 /* PCE tag */);
pceBuffer.readBits(newConfig, oldConfig.length, numPceBits);

// Submit PCE-appended output format.
currentOutput.format(pendingOutputFormat);
hasOutputFormat = true;
}
}
}
pendingOutputFormat =
pendingOutputFormat.buildUpon().setInitializationData(ImmutableList.of(newConfig)).build();

// Submit PCE-appended output format.
this.currentOutput.format(pendingOutputFormat);
this.hasOutputFormat = true;

// Pass through all accumulated data as sample data.
ParsableByteArray data = new ParsableByteArray(pceBuffer.data);
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16 changes: 15 additions & 1 deletion libraries/extractor/src/test/java/androidx/media3/extractor/ts/AdtsReaderTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -209,6 +209,20 @@ public void aacPceData() throws ParserException {
adtsOutput.assertSample(0, AAC_PCE_ADTS_CONTENT, 0, C.BUFFER_FLAG_KEY_FRAME, null);
}

@Test
public void aacPceDataSplit() throws ParserException {
byte[] first = Arrays.copyOf(AAC_PCE_TEST_DATA, AAC_PCE_ADTS_HEADER.length + 1);
byte[] second = Arrays.copyOfRange(AAC_PCE_TEST_DATA, AAC_PCE_ADTS_HEADER.length + 1, AAC_PCE_TEST_DATA.length);

data = new ParsableByteArray(first);
feed();
data = new ParsableByteArray(second);
feed();

assertSampleCounts(0, 1);
adtsOutput.assertSample(0, AAC_PCE_ADTS_CONTENT, 0, C.BUFFER_FLAG_KEY_FRAME, null);
}

@Test
public void aacPceDataFail() throws ParserException {
data = new ParsableByteArray(Arrays.copyOf(AAC_PCE_TEST_DATA, AAC_PCE_TEST_DATA.length));
Expand All @@ -219,7 +233,7 @@ public void aacPceDataFail() throws ParserException {
bytes[AAC_PCE_ADTS_HEADER.length] |= 0x20;

// Should throw as FakeTrackOutput expects a format before sampleMetadata.
assertThrows(IllegalStateException.class, this::feed);
assertThrows(ParserException.class, this::feed);
}

private void feedLimited(int limit) throws ParserException {
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