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Prepend Ogg ID and Comment Header Pages to offloaded Opus stream
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Add Ogg ID Header and Comment Header Pages to the Ogg encapsulated Opus for offload playback. This further matches the RFC 7845 spec and provides initialization data to decoders.

PiperOrigin-RevId: 548080222
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@microkatz @icbaker
microkatz authored and icbaker committed Jul 20, 2023
1 parent 11e3219 commit 847f6f2
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Showing 6 changed files with 314 additions and 51 deletions.
2 changes: 2 additions & 0 deletions RELEASENOTES.md
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Expand Up @@ -75,6 +75,8 @@
in offload, then no track will be selected.
* Disabling gapless support for offload when pre-API level 33 due to
playback position issue after track transition.
* Prepend Ogg ID Header and Comment Header Pages to bitstream for
offloaded Opus playback in accordance with RFC 7845.
* Remove parameter `enableOffload` from
`DefaultRenderersFactory.buildAudioSink` method signature.
* Remove method `DefaultAudioSink.Builder.setOffloadMode`.
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197 changes: 160 additions & 37 deletions ...aries/exoplayer/src/main/java/androidx/media3/exoplayer/audio/OggOpusAudioPacketizer.java
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Expand Up @@ -18,19 +18,37 @@
import static androidx.media3.common.audio.AudioProcessor.EMPTY_BUFFER;
import static androidx.media3.common.util.Assertions.checkNotNull;

import androidx.annotation.Nullable;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.common.util.Util;
import androidx.media3.decoder.DecoderInputBuffer;
import androidx.media3.extractor.OpusUtil;
import com.google.common.primitives.UnsignedBytes;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.List;

/** A packetizer that encapsulates OPUS audio encodings in OGG packets. */
/** A packetizer that encapsulates Opus audio encodings in Ogg packets. */
@UnstableApi
public final class OggOpusAudioPacketizer {

private static final int CHECKSUM_INDEX = 22;

/** ID Header and Comment Header pages are 0 and 1 respectively */
private static final int FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE = 2;
private static final int FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE_NUMBER = 2;

private static final int OGG_PACKET_HEADER_LENGTH = 28;
private static final int SERIAL_NUMBER = 0;
private static final byte[] OGG_DEFAULT_ID_HEADER_PAGE =
new byte[] {
79, 103, 103, 83, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 28, -43, -59, -9, 1,
19, 79, 112, 117, 115, 72, 101, 97, 100, 1, 2, 56, 1, -128, -69, 0, 0, 0, 0, 0
};
private static final byte[] OGG_DEFAULT_COMMENT_HEADER_PAGE =
new byte[] {
79, 103, 103, 83, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 11, -103, 87, 83, 1,
16, 79, 112, 117, 115, 84, 97, 103, 115, 0, 0, 0, 0, 0, 0, 0, 0
};

private ByteBuffer outputBuffer;
private int pageSequenceNumber;
Expand All @@ -40,7 +58,7 @@ public final class OggOpusAudioPacketizer {
public OggOpusAudioPacketizer() {
outputBuffer = EMPTY_BUFFER;
granulePosition = 0;
pageSequenceNumber = FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE;
pageSequenceNumber = FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE_NUMBER;
}

/**
Expand All @@ -49,13 +67,23 @@ public OggOpusAudioPacketizer() {
* @param inputBuffer The input buffer to packetize. It must be a direct {@link ByteBuffer} with
* LITTLE_ENDIAN order. The contents will be overwritten with the Ogg packet. The caller
* retains ownership of the provided buffer.
* @param initializationData contains set-up data for the Opus Decoder. The data will be provided
* in an Ogg ID Header Page prepended to the bitstream. The list should contain either one or
* three byte arrays. The first item is the payload for the Ogg ID Header Page. If three
* items, then it also contains the Opus pre-skip and seek pre-roll values in that order.
*/
public void packetize(DecoderInputBuffer inputBuffer) {
public void packetize(DecoderInputBuffer inputBuffer, List<byte[]> initializationData) {
checkNotNull(inputBuffer.data);
if (inputBuffer.data.limit() - inputBuffer.data.position() == 0) {
return;
}
outputBuffer = packetizeInternal(inputBuffer.data);
@Nullable
byte[] providedOggIdHeaderPayloadBytes =
pageSequenceNumber == FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE_NUMBER
&& (initializationData.size() == 1 || initializationData.size() == 3)
? initializationData.get(0)
: null;
outputBuffer = packetizeInternal(inputBuffer.data, providedOggIdHeaderPayloadBytes);
inputBuffer.clear();
inputBuffer.ensureSpaceForWrite(outputBuffer.remaining());
inputBuffer.data.put(outputBuffer);
Expand All @@ -66,16 +94,24 @@ public void packetize(DecoderInputBuffer inputBuffer) {
public void reset() {
outputBuffer = EMPTY_BUFFER;
granulePosition = 0;
pageSequenceNumber = FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE;
pageSequenceNumber = FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE_NUMBER;
}

/**
* Fill outputBuffer with an Ogg packet encapsulating the inputBuffer.
*
* @param inputBuffer contains Opus to wrap in Ogg packet
* <p>If {@code providedOggIdHeaderPayloadBytes} is {@code null} and {@link #pageSequenceNumber}
* is {@link #FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE_NUMBER}, then {@link #OGG_DEFAULT_ID_HEADER_PAGE}
* will be prepended to the Ogg Opus Audio packets for the Ogg ID Header Page.
*
* @param inputBuffer contains Opus to wrap in Ogg packet.
* @param providedOggIdHeaderPayloadBytes containing the Ogg ID Header Page payload. Expected to
* be {@code null} if {@link #pageSequenceNumber} is not {@link
* #FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE_NUMBER}.
* @return {@link ByteBuffer} containing Ogg packet
*/
private ByteBuffer packetizeInternal(ByteBuffer inputBuffer) {
private ByteBuffer packetizeInternal(
ByteBuffer inputBuffer, @Nullable byte[] providedOggIdHeaderPayloadBytes) {
int position = inputBuffer.position();
int limit = inputBuffer.limit();
int inputBufferSize = limit - position;
Expand All @@ -86,38 +122,37 @@ private ByteBuffer packetizeInternal(ByteBuffer inputBuffer) {

int outputPacketSize = headerSize + inputBufferSize;

// If first audio sample in stream, then the packetizer will add Ogg ID Header and Comment
// Header Pages. Include additional page lengths in buffer size calculation.
int oggIdHeaderPageSize = 0;
if (pageSequenceNumber == FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE_NUMBER) {
oggIdHeaderPageSize =
providedOggIdHeaderPayloadBytes != null
? OGG_PACKET_HEADER_LENGTH + providedOggIdHeaderPayloadBytes.length
: OGG_DEFAULT_ID_HEADER_PAGE.length;
outputPacketSize += oggIdHeaderPageSize + OGG_DEFAULT_COMMENT_HEADER_PAGE.length;
}

// Resample the little endian input and update the output buffers.
ByteBuffer buffer = replaceOutputBuffer(outputPacketSize);

// Capture Pattern for Page [OggS]
buffer.put((byte) 'O');
buffer.put((byte) 'g');
buffer.put((byte) 'g');
buffer.put((byte) 'S');

// StreamStructure Version
buffer.put((byte) 0);

// header_type_flag
buffer.put((byte) 0x00);
// If first audio sample in stream then insert Ogg ID Header and Comment Header Pages
if (pageSequenceNumber == FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE_NUMBER) {
if (providedOggIdHeaderPayloadBytes != null) {
writeOggIdHeaderPage(buffer, /* idHeaderPayloadBytes= */ providedOggIdHeaderPayloadBytes);
} else {
// Write default Ogg ID Header Payload
buffer.put(OGG_DEFAULT_ID_HEADER_PAGE);
}
buffer.put(OGG_DEFAULT_COMMENT_HEADER_PAGE);
}

// granule_position
int numSamples = OpusUtil.parsePacketAudioSampleCount(inputBuffer);
granulePosition += numSamples;
buffer.putLong(granulePosition);

// bitstream_serial_number
buffer.putInt(0);

// page_sequence_number
buffer.putInt(pageSequenceNumber);
pageSequenceNumber++;

// CRC_checksum
buffer.putInt(0);

// number_page_segments
buffer.put((byte) numSegments);
writeOggPacketHeader(
buffer, granulePosition, pageSequenceNumber, numSegments, /* isIdHeaderPacket= */ false);

// Segment_table
int bytesLeft = inputBufferSize;
Expand All @@ -131,23 +166,111 @@ private ByteBuffer packetizeInternal(ByteBuffer inputBuffer) {
}
}

// Write Opus audio data
for (int i = position; i < limit; i++) {
buffer.put(inputBuffer.get(i));
}

inputBuffer.position(inputBuffer.limit());
buffer.flip();

int checksum;
if (pageSequenceNumber == FIRST_AUDIO_SAMPLE_PAGE_SEQUENCE_NUMBER) {
checksum =
Util.crc32(
buffer.array(),
/* start= */ buffer.arrayOffset()
+ oggIdHeaderPageSize
+ OGG_DEFAULT_COMMENT_HEADER_PAGE.length,
/* end= */ buffer.limit() - buffer.position(),
/* initialValue= */ 0);
buffer.putInt(
oggIdHeaderPageSize + OGG_DEFAULT_COMMENT_HEADER_PAGE.length + CHECKSUM_INDEX, checksum);
} else {
checksum =
Util.crc32(
buffer.array(),
/* start= */ buffer.arrayOffset(),
/* end= */ buffer.limit() - buffer.position(),
/* initialValue= */ 0);
buffer.putInt(CHECKSUM_INDEX, checksum);
}

// Increase pageSequenceNumber for next packet
pageSequenceNumber++;

return buffer;
}

/**
* Write Ogg ID Header Page packet to {@link ByteBuffer}.
*
* @param buffer to write into.
* @param idHeaderPayloadBytes containing the Ogg ID Header Page payload.
*/
private void writeOggIdHeaderPage(ByteBuffer buffer, byte[] idHeaderPayloadBytes) {
// TODO(b/290195621): Use starting position to calculate correct 'pre-skip' value
writeOggPacketHeader(
buffer,
/* granulePosition= */ 0,
/* pageSequenceNumber= */ 0,
/* numberPageSegments= */ 1,
/* isIdHeaderPacket= */ true);
buffer.put(UnsignedBytes.checkedCast(idHeaderPayloadBytes.length));
buffer.put(idHeaderPayloadBytes);
int checksum =
Util.crc32(
buffer.array(),
buffer.arrayOffset(),
buffer.limit() - buffer.position(),
/* start= */ buffer.arrayOffset(),
/* end= */ OGG_PACKET_HEADER_LENGTH + idHeaderPayloadBytes.length,
/* initialValue= */ 0);
buffer.putInt(22, checksum);
buffer.position(0);
buffer.putInt(/* index= */ CHECKSUM_INDEX, checksum);
buffer.position(OGG_PACKET_HEADER_LENGTH + idHeaderPayloadBytes.length);
}

return buffer;
/**
* Write header for an Ogg Page Packet to {@link ByteBuffer}.
*
* @param byteBuffer to write unto.
* @param granulePosition is the number of audio samples in the stream up to and including this
* packet.
* @param pageSequenceNumber of the page this header is for.
* @param numberPageSegments the data of this Ogg page will span.
* @param isIdHeaderPacket where if this header is start of the bitstream.
*/
private void writeOggPacketHeader(
ByteBuffer byteBuffer,
long granulePosition,
int pageSequenceNumber,
int numberPageSegments,
boolean isIdHeaderPacket) {
// Capture Pattern for Ogg Page [OggS]
byteBuffer.put((byte) 'O');
byteBuffer.put((byte) 'g');
byteBuffer.put((byte) 'g');
byteBuffer.put((byte) 'S');

// StreamStructure Version
byteBuffer.put((byte) 0);

// Header-type
byteBuffer.put(isIdHeaderPacket ? (byte) 0x02 : (byte) 0x00);

// Granule_position
byteBuffer.putLong(granulePosition);

// bitstream_serial_number
byteBuffer.putInt(SERIAL_NUMBER);

// Page_sequence_number
byteBuffer.putInt(pageSequenceNumber);

// CRC_checksum
// Will be overwritten with calculated checksum after rest of page is written to buffer.
byteBuffer.putInt(0);

// Number_page_segments
byteBuffer.put(UnsignedBytes.checkedCast(numberPageSegments));
}

/**
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3 changes: 2 additions & 1 deletion ...ries/exoplayer/src/main/java/androidx/media3/exoplayer/mediacodec/MediaCodecRenderer.java
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Expand Up @@ -720,6 +720,7 @@ protected void onPositionReset(long positionUs, boolean joining) throws ExoPlayb
bypassBatchBuffer.clear();
bypassSampleBuffer.clear();
bypassSampleBufferPending = false;
oggOpusAudioPacketizer.reset();
} else {
flushOrReinitializeCodec();
}
Expand Down Expand Up @@ -2349,7 +2350,7 @@ private void bypassRead() throws ExoPlaybackException {
if (inputFormat != null
&& inputFormat.sampleMimeType != null
&& inputFormat.sampleMimeType.equals(MimeTypes.AUDIO_OPUS)) {
oggOpusAudioPacketizer.packetize(bypassSampleBuffer);
oggOpusAudioPacketizer.packetize(bypassSampleBuffer, inputFormat.initializationData);
}
if (!bypassBatchBuffer.append(bypassSampleBuffer)) {
bypassSampleBufferPending = true;
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36 changes: 33 additions & 3 deletions libraries/extractor/src/main/java/androidx/media3/extractor/OpusUtil.java
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Expand Up @@ -76,15 +76,45 @@ public static List<byte[]> buildInitializationData(byte[] header) {
*/
public static int parseOggPacketAudioSampleCount(ByteBuffer buffer) {
// RFC 3433 section 6 - The Ogg page format.
int numPageSegments = buffer.get(/* index= */ 26);
int indexFirstOpusPacket = 27 + numPageSegments; // Skip Ogg header and segment table.
int preAudioPacketByteCount = parseOggPacketForPreAudioSampleByteCount(buffer);
int numPageSegments = buffer.get(/* index= */ 26 + preAudioPacketByteCount);
// Skip Ogg header + segment table.
int indexFirstOpusPacket = 27 + numPageSegments + preAudioPacketByteCount;
long packetDurationUs =
getPacketDurationUs(
buffer.get(indexFirstOpusPacket),
buffer.limit() > 1 ? buffer.get(indexFirstOpusPacket + 1) : 0);
buffer.limit() - indexFirstOpusPacket > 1 ? buffer.get(indexFirstOpusPacket + 1) : 0);
return (int) (packetDurationUs * SAMPLE_RATE / C.MICROS_PER_SECOND);
}

/**
* Calculate the offset from the start of the buffer to audio sample Ogg packets.
*
* @param buffer containing the Ogg Encapsulated Opus audio bitstream.
* @return the offset before the Ogg packet containing audio samples.
*/
public static int parseOggPacketForPreAudioSampleByteCount(ByteBuffer buffer) {
// Parse Ogg Packet Type from Header at index 5
if ((buffer.get(/* index= */ 5) & 0x02) == 0) {
// Ogg Page packet header type is not beginning of logical stream. Must be an Audio page.
return 0;
}
// ID Header Page size is Ogg packet header size + sum(lacing values: 1..number_page_segments).
int idHeaderPageSize = 28;
int idHeaderPageNumOfSegments = buffer.get(/* index= */ 26);
for (int i = 0; i < idHeaderPageNumOfSegments; i++) {
idHeaderPageSize += buffer.get(/* index= */ 27 + i);
}
// Comment Header Page size is Ogg packet header size + sum(lacing values:
// 1..number_page_segments).
int commentHeaderPageSize = 28;
int commentHeaderPageSizeNumOfSegments = buffer.get(/* index= */ idHeaderPageSize + 26);
for (int i = 0; i < commentHeaderPageSizeNumOfSegments; i++) {
commentHeaderPageSize += buffer.get(/* index= */ idHeaderPageSize + 27 + i);
}
return idHeaderPageSize + commentHeaderPageSize;
}

/**
* Returns the number of audio samples in the given audio packet.
*
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