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@rohitjoins
rohitjoins committed Nov 29, 2023
1 parent 2c3eac4 commit 83cc9e2
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Showing 2 changed files with 67 additions and 73 deletions.
138 changes: 66 additions & 72 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 @@ -101,7 +101,6 @@ public final class AdtsReader implements ElementaryStreamReader {

// Used when reading the AAC PCE.
@Nullable private Format pendingOutputFormat;
@Nullable private ParsableBitArray pceBuffer;

// Used when reading the samples.
private long timeUs;
Expand Down Expand Up @@ -192,10 +191,11 @@ public void consume(ParsableByteArray data) throws ParserException {
}
break;
case STATE_READING_AAC_PCE:
checkNotNull(pceBuffer);
if (continueRead(data, pceBuffer.data, pceBuffer.data.length)) {
readAacProgramConfigElement();
}
int offset = data.getPosition();
int limit = offset + min(sampleSize, AAC_PCE_MAX_SIZE);
ParsableBitArray pceBuffer =
new ParsableBitArray(Arrays.copyOfRange(data.getData(), offset, limit));
readAacProgramConfigElement(pceBuffer);
break;
case STATE_READING_SAMPLE:
readSample(data);
Expand Down Expand Up @@ -301,7 +301,6 @@ private void setReadingAacPceState(
this.currentOutput = outputToUse;
this.currentSampleDuration = currentSampleDuration;
this.sampleSize = sampleSize;
pceBuffer = new ParsableBitArray(new byte[min(sampleSize, AAC_PCE_MAX_SIZE)]);
}

/**
Expand Down Expand Up @@ -573,87 +572,82 @@ private void parseAdtsHeader() throws ParserException {
}
}

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

private void readAacProgramConfigElement(ParsableBitArray pceBuffer) throws ParserException {
// 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 */;

int configSize = oldConfig.length;
configSize += (numPceBits + 7) / 8 + 1; // Byte align and add a zero length comment.
byte[] newConfig = Arrays.copyOf(oldConfig, configSize);
pceBuffer.skipBits(numAlignmentBits);
int commentSize = pceBuffer.readBits(commentSizeBits);

pceBuffer.setPosition(3 /* PCE tag */);
pceBuffer.readBits(newConfig, oldConfig.length, numPceBits);
if (sampleSize < pceBuffer.getBytePosition() + commentSize) {
throw ParserException.createForMalformedContainer(/* message= */ null, /* cause= */ null);
}

pendingOutputFormat =
pendingOutputFormat
.buildUpon()
.setInitializationData(ImmutableList.of(newConfig))
.build();
Format pendingOutputFormat = checkNotNull(this.pendingOutputFormat);
// Append PCE to format's audio specific config.
byte[] oldConfig = pendingOutputFormat.initializationData.get(0);

// Submit PCE-appended output format.
currentOutput.format(pendingOutputFormat);
hasOutputFormat = true;
}
}
}
int configSize = oldConfig.length;
configSize += (numPceBits + 7) / 8 + 1; // Byte align and add a zero length comment.
byte[] newConfig = Arrays.copyOf(oldConfig, configSize);

// Pass through all accumulated data as sample data.
ParsableByteArray data = new ParsableByteArray(pceBuffer.data);
setReadingSampleState(currentOutput, currentSampleDuration, 0, sampleSize);
readSample(data);
pceBuffer.setPosition(3 /* PCE tag */);
pceBuffer.readBits(newConfig, oldConfig.length, numPceBits);

pendingOutputFormat =
pendingOutputFormat.buildUpon().setInitializationData(ImmutableList.of(newConfig)).build();

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

setReadingSampleState(currentOutput, currentSampleDuration, 0, sampleSize);
}

/** Reads the rest of the sample */
Expand Down
2 changes: 1 addition & 1 deletion libraries/extractor/src/test/java/androidx/media3/extractor/ts/AdtsReaderTest.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -219,7 +219,7 @@ 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 {
Expand Down

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