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Add support for RTSP VP9 #64

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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,7 @@ public final class RtpPayloadFormat {
private static final String RTP_MEDIA_PCMA = "PCMA";
private static final String RTP_MEDIA_PCMU = "PCMU";
private static final String RTP_MEDIA_VP8 = "VP8";
private static final String RTP_MEDIA_VP9 = "VP9";

/** Returns whether the format of a {@link MediaDescription} is supported. */
public static boolean isFormatSupported(MediaDescription mediaDescription) {
Expand All @@ -67,6 +68,7 @@ public static boolean isFormatSupported(MediaDescription mediaDescription) {
case RTP_MEDIA_PCMA:
case RTP_MEDIA_PCMU:
case RTP_MEDIA_VP8:
case RTP_MEDIA_VP9:
return true;
default:
return false;
Expand Down Expand Up @@ -101,10 +103,14 @@ public static String getMimeTypeFromRtpMediaType(String mediaType) {
return MimeTypes.VIDEO_H264;
case RTP_MEDIA_H265:
return MimeTypes.VIDEO_H265;
case RTP_MEDIA_MPEG4_GENERIC:
return MimeTypes.AUDIO_AAC;
case RTP_MEDIA_MPEG4_VIDEO:
return MimeTypes.VIDEO_MP4V;
case RTP_MEDIA_VP8:
return MimeTypes.VIDEO_VP8;
case RTP_MEDIA_VP9:
return MimeTypes.VIDEO_VP9;
default:
throw new IllegalArgumentException(mediaType);
}
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -101,6 +101,27 @@
*/
private static final int DEFAULT_VP8_HEIGHT = 240;

/**
* Default width for VP9.
*
* <p>VP9 RFC (<a href=https://datatracker.ietf.org/doc/html/draft-ietf-payload-vp9> this draft
* RFC</a>) never uses codec specific data (like width and height) in the fmtp attribute. These
* values are taken from <a
* href=https://cs.android.com/android/platform/superproject/+/master:frameworks/av/media/codec2/components/vpx/C2SoftVpxDec.cpp;drc=749a74cc3e081c16ea0e8c530953d0a247177867;l=70>Android's
* software VP9 decoder</a>.
*/
private static final int DEFAULT_VP9_WIDTH = 320;
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/**
* Default height for VP9.
*
* <p>VP9 RFC (<a href=https://datatracker.ietf.org/doc/html/draft-ietf-payload-vp9> this draft
* RFC</a>) never uses codec specific data (like width and height) in the fmtp attribute. These
* values are taken from <a
* href=https://cs.android.com/android/platform/superproject/+/master:frameworks/av/media/codec2/components/vpx/C2SoftVpxDec.cpp;drc=749a74cc3e081c16ea0e8c530953d0a247177867;l=70>Android's
* software VP9 decoder</a>.
*/
private static final int DEFAULT_VP9_HEIGHT = 240;

/** The track's associated {@link RtpPayloadFormat}. */
public final RtpPayloadFormat payloadFormat;
/** The track's URI. */
Expand Down Expand Up @@ -197,6 +218,10 @@ public int hashCode() {
// width and height.
formatBuilder.setWidth(DEFAULT_VP8_WIDTH).setHeight(DEFAULT_VP8_HEIGHT);
break;
case MimeTypes.VIDEO_VP9:
// VP9 never uses fmtp width and height attributes, setting default width and height.
formatBuilder.setWidth(DEFAULT_VP9_WIDTH).setHeight(DEFAULT_VP9_HEIGHT);
break;
case MimeTypes.AUDIO_RAW:
formatBuilder.setPcmEncoding(RtpPayloadFormat.getRawPcmEncodingType(mediaEncoding));
break;
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,8 @@ public RtpPayloadReader createPayloadReader(RtpPayloadFormat payloadFormat) {
return new RtpMpeg4Reader(payloadFormat);
case MimeTypes.VIDEO_VP8:
return new RtpVp8Reader(payloadFormat);
case MimeTypes.VIDEO_VP9:
return new RtpVp9Reader(payloadFormat);
default:
// No supported reader, returning null.
}
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,240 @@
/*
* Copyright 2022 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.media3.exoplayer.rtsp.reader;

import static androidx.media3.common.util.Assertions.checkArgument;
import static androidx.media3.common.util.Assertions.checkStateNotNull;

import androidx.media3.common.C;
import androidx.media3.common.ParserException;
import androidx.media3.common.util.Log;
import androidx.media3.common.util.ParsableByteArray;
import androidx.media3.common.util.Util;
import androidx.media3.exoplayer.rtsp.RtpPacket;
import androidx.media3.exoplayer.rtsp.RtpPayloadFormat;
import androidx.media3.extractor.ExtractorOutput;
import androidx.media3.extractor.TrackOutput;
import org.checkerframework.checker.nullness.qual.MonotonicNonNull;

/**
* Parses an VP9 byte stream carried on RTP packets, and extracts VP9 Access Units. Refer to <a
* href=https://datatracker.ietf.org/doc/html/draft-ietf-payload-vp9> this draft RFC</a> for more
* details.
*/
/* package */ final class RtpVp9Reader implements RtpPayloadReader {

private static final String TAG = "RtpVp9Reader";

private static final long MEDIA_CLOCK_FREQUENCY = 90_000;
private static final int SCALABILITY_STRUCTURE_SIZE = 4;

private final RtpPayloadFormat payloadFormat;

private @MonotonicNonNull TrackOutput trackOutput;

/**
* First received RTP timestamp. All RTP timestamps are dimension-less, the time base is defined
* by {@link #MEDIA_CLOCK_FREQUENCY}.
*/
private long firstReceivedTimestamp;
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private long startTimeOffsetUs;
private int previousSequenceNumber;
/** The combined size of a sample that is fragmented into multiple RTP packets. */
private int fragmentedSampleSizeBytes;
private int width;
private int height;
/**
* Whether the first packet of one VP9 frame is received, it mark the start of a VP9 partition.
* A VP9 frame can be split into multiple RTP packets.
*/
private boolean gotFirstPacketOfVP9Frame;
private boolean isKeyFrame;
private boolean isOutputFormatSet;

/** Creates an instance. */
public RtpVp9Reader(RtpPayloadFormat payloadFormat) {
this.payloadFormat = payloadFormat;
firstReceivedTimestamp = C.TIME_UNSET;
startTimeOffsetUs = 0; // The start time offset must be 0 until the first seek.
previousSequenceNumber = C.INDEX_UNSET;
fragmentedSampleSizeBytes = 0;
width = C.LENGTH_UNSET;
height = C.LENGTH_UNSET;
gotFirstPacketOfVP9Frame = false;
isKeyFrame = false;
isOutputFormatSet = false;
}

@Override
public void createTracks(ExtractorOutput extractorOutput, int trackId) {
trackOutput = extractorOutput.track(trackId, C.TRACK_TYPE_VIDEO);
trackOutput.format(payloadFormat.format);
}

@Override
public void onReceivingFirstPacket(long timestamp, int sequenceNumber) {}

@Override
public void consume(ParsableByteArray data, long timestamp, int sequenceNumber, boolean rtpMarker)
throws ParserException {
checkStateNotNull(trackOutput);

if (validateVp9Descriptor(data, sequenceNumber)) {
if (fragmentedSampleSizeBytes == 0 && gotFirstPacketOfVP9Frame) {
isKeyFrame = (data.peekUnsignedByte() & 0x04) == 0;
}

if (!isOutputFormatSet && width != C.LENGTH_UNSET && height != C.LENGTH_UNSET) {
if (width != payloadFormat.format.width || height != payloadFormat.format.height) {
trackOutput.format(
payloadFormat.format.buildUpon().setWidth(width).setHeight(height).build());
}
isOutputFormatSet = true;
}

int fragmentSize = data.bytesLeft();
// Write the video sample.
trackOutput.sampleData(data, fragmentSize);
fragmentedSampleSizeBytes += fragmentSize;

if (rtpMarker) {
if (firstReceivedTimestamp == C.TIME_UNSET) {
firstReceivedTimestamp = timestamp;
}
long timeUs = toSampleUs(startTimeOffsetUs, timestamp, firstReceivedTimestamp);
trackOutput.sampleMetadata(
timeUs,
isKeyFrame ? C.BUFFER_FLAG_KEY_FRAME : 0,
fragmentedSampleSizeBytes,
/* offset= */ 0,
/* cryptoData= */ null);
fragmentedSampleSizeBytes = 0;
gotFirstPacketOfVP9Frame = false;
}
previousSequenceNumber = sequenceNumber;
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can you check if moving this line to out of the if (validateVp9Descriptor(data, sequenceNumber)) works? i.e. move it down one line.

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By moving "previousSequenceNumber = sequenceNumber;" down, packet(s) with Invalid Payload Descriptor will also get logged in previousSequenceNumber which can lead to directly get follow-on packet without start Code packet.

}
}

@Override
public void seek(long nextRtpTimestamp, long timeUs) {
firstReceivedTimestamp = nextRtpTimestamp;
fragmentedSampleSizeBytes = 0;
startTimeOffsetUs = timeUs;
}

// Internal methods.
private static long toSampleUs(
long startTimeOffsetUs, long rtpTimestamp, long firstReceivedRtpTimestamp) {
return startTimeOffsetUs
+ Util.scaleLargeTimestamp(
(rtpTimestamp - firstReceivedRtpTimestamp),
/* multiplier= */ C.MICROS_PER_SECOND,
/* divisor= */ MEDIA_CLOCK_FREQUENCY);
}

/**
* Returns {@code true} and sets the {@link ParsableByteArray#getPosition() payload.position} to
* the end of the descriptor, if a valid VP9 descriptor is present.
*/
private boolean validateVp9Descriptor(ParsableByteArray payload, int packetSequenceNumber)
throws ParserException {
// VP9 Payload Descriptor, Section 4.2
// 0 1 2 3 4 5 6 7
// +-+-+-+-+-+-+-+-+
// |I|P|L|F|B|E|V|Z| (REQUIRED)
// +-+-+-+-+-+-+-+-+
// I: |M| PICTURE ID | (RECOMMENDED)
// +-+-+-+-+-+-+-+-+
// M: | EXTENDED PID | (RECOMMENDED)
// +-+-+-+-+-+-+-+-+
// L: | TID |U| SID |D| (Conditionally RECOMMENDED)
// +-+-+-+-+-+-+-+-+
// | TL0PICIDX | (Conditionally REQUIRED)
// +-+-+-+-+-+-+-+-+
// V: | SS |
// | .. |
// +-+-+-+-+-+-+-+-+

int header = payload.readUnsignedByte();
if (!gotFirstPacketOfVP9Frame) {
if ((header & 0x08) == 0) {
Log.w(
TAG,
"First payload octet of the RTP packet is not the beginning of a new VP9 partition,"
+ " Dropping current packet.");
return false;
}
gotFirstPacketOfVP9Frame = true;
} else {
// Check that this packet is in the sequence of the previous packet.
int expectedSequenceNumber = RtpPacket.getNextSequenceNumber(previousSequenceNumber);
if (packetSequenceNumber != expectedSequenceNumber) {
Log.w(
TAG,
Util.formatInvariant(
"Received RTP packet with unexpected sequence number. Expected: %d; received: %d."
+ " Dropping packet.",
expectedSequenceNumber, packetSequenceNumber));
return false;
}
}

// Check if optional I header is present.
if ((header & 0x80) != 0) {
int optionalHeader = payload.readUnsignedByte();
// Check M for 15 bits PictureID.
if ((optionalHeader & 0x80) != 0) {
if (payload.bytesLeft() < 1) {
return false;
}
}
}

// Flexible-mode not implemented.
checkArgument((header & 0x10) == 0, "VP9 flexible mode unsupported");
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  • Please specify the reason not to support it
  • Move this check above to right after getting the header.

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Live555 doesn't support flexible mode, there are only reading and passing required Payload Descriptor (|I|P|L|F|B|E|V|Z|).


// Check if optional L header is present.
if ((header & 0x20) != 0) {
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payload.skipBytes(1);
if (payload.bytesLeft() < 1) {
return false;
}
// Check if TL0PICIDX header present (non-flexible mode).
if ((header & 0x10) == 0) {
payload.skipBytes(1);
}
}

// Check if optional V header is present, Refer Section 4.2.1.
if ((header & 0x02) != 0) {
int scalabilityStructure = payload.readUnsignedByte();
int numSpatialLayers = (scalabilityStructure >> 5) & 0x7 ;
int scalabilityStructureLength =
((scalabilityStructure & 0x10) != 0) ? numSpatialLayers + 1 : 0;

if ((scalabilityStructure & 0x10) != 0) {
if (payload.bytesLeft() < scalabilityStructureLength * SCALABILITY_STRUCTURE_SIZE) {
return false;
}
for (int index = 0; index < scalabilityStructureLength; index++) {
width = payload.readUnsignedShort();
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height = payload.readUnsignedShort();
}
}
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}
return true;
}
}