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Merge pull request #64 from ittiam-systems:rtp-vp9
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261
...ary/rtsp/src/main/java/com/google/android/exoplayer2/source/rtsp/reader/RtpVp9Reader.java
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| Original file line number | Diff line number | Diff line change |
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| /* | ||
| * 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 com.google.android.exoplayer2.source.rtsp.reader; | ||
|
|
||
| import static com.google.android.exoplayer2.util.Assertions.checkArgument; | ||
| import static com.google.android.exoplayer2.util.Assertions.checkStateNotNull; | ||
|
|
||
| import com.google.android.exoplayer2.C; | ||
| import com.google.android.exoplayer2.extractor.ExtractorOutput; | ||
| import com.google.android.exoplayer2.extractor.TrackOutput; | ||
| import com.google.android.exoplayer2.source.rtsp.RtpPacket; | ||
| import com.google.android.exoplayer2.source.rtsp.RtpPayloadFormat; | ||
| import com.google.android.exoplayer2.util.Log; | ||
| import com.google.android.exoplayer2.util.ParsableByteArray; | ||
| import com.google.android.exoplayer2.util.Util; | ||
| import org.checkerframework.checker.nullness.qual.MonotonicNonNull; | ||
|
|
||
| /** | ||
| * Parses a 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"; | ||
|
|
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| private static final long MEDIA_CLOCK_FREQUENCY = 90_000; | ||
| private static final int SCALABILITY_STRUCTURE_SIZE = 4; | ||
|
|
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| private final RtpPayloadFormat payloadFormat; | ||
|
|
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| 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; | ||
|
|
||
| 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 a 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; | ||
|
|
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| private boolean reportedOutputFormat; | ||
|
|
||
| /** Creates an instance. */ | ||
| public RtpVp9Reader(RtpPayloadFormat payloadFormat) { | ||
| this.payloadFormat = payloadFormat; | ||
| firstReceivedTimestamp = C.TIME_UNSET; | ||
| // The start time offset must be 0 until the first seek. | ||
| startTimeOffsetUs = 0; | ||
| previousSequenceNumber = C.INDEX_UNSET; | ||
| width = C.LENGTH_UNSET; | ||
| height = C.LENGTH_UNSET; | ||
| gotFirstPacketOfVP9Frame = false; | ||
| reportedOutputFormat = 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) { | ||
| checkStateNotNull(trackOutput); | ||
|
|
||
| if (validateVp9Descriptor(data, sequenceNumber)) { | ||
| @C.BufferFlags int bufferFlags = 0; | ||
| if (fragmentedSampleSizeBytes == 0 | ||
| && gotFirstPacketOfVP9Frame | ||
| && (data.peekUnsignedByte() & 0x04) == 0) { | ||
| bufferFlags = C.BUFFER_FLAG_KEY_FRAME; | ||
| } | ||
|
|
||
| if (!reportedOutputFormat && 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()); | ||
| } | ||
| reportedOutputFormat = true; | ||
| } | ||
|
|
||
| int currentFragmentSizeBytes = data.bytesLeft(); | ||
| // Write the video sample. | ||
| trackOutput.sampleData(data, currentFragmentSizeBytes); | ||
| fragmentedSampleSizeBytes += currentFragmentSizeBytes; | ||
|
|
||
| if (rtpMarker) { | ||
| if (firstReceivedTimestamp == C.TIME_UNSET) { | ||
| firstReceivedTimestamp = timestamp; | ||
| } | ||
| long timeUs = toSampleUs(startTimeOffsetUs, timestamp, firstReceivedTimestamp); | ||
| trackOutput.sampleMetadata( | ||
| timeUs, | ||
| bufferFlags, | ||
| fragmentedSampleSizeBytes, | ||
| /* offset= */ 0, | ||
| /* cryptoData= */ null); | ||
| fragmentedSampleSizeBytes = 0; | ||
| gotFirstPacketOfVP9Frame = false; | ||
| } | ||
| previousSequenceNumber = sequenceNumber; | ||
| } | ||
| } | ||
|
|
||
| @Override | ||
| public void seek(long nextRtpTimestamp, long timeUs) { | ||
| firstReceivedTimestamp = nextRtpTimestamp; | ||
| fragmentedSampleSizeBytes = 0; | ||
| startTimeOffsetUs = timeUs; | ||
| } | ||
|
|
||
| // Internal methods. | ||
| /** | ||
| * 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) { | ||
| // 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 is not implemented. | ||
| checkArgument((header & 0x10) == 0, "VP9 flexible mode is not supported."); | ||
|
|
||
| // Check if the optional L header is present. | ||
| if ((header & 0x20) != 0) { | ||
| 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 the optional V header is present, Refer to RFC Section 4.2.1. | ||
| if ((header & 0x02) != 0) { | ||
| int scalabilityStructure = payload.readUnsignedByte(); | ||
| int spatialLayersCount = (scalabilityStructure >> 5) & 0x7; | ||
|
|
||
| // Check Y bit. | ||
| if ((scalabilityStructure & 0x10) != 0) { | ||
| int scalabilityStructureCount = spatialLayersCount + 1; | ||
| if (payload.bytesLeft() < scalabilityStructureCount * SCALABILITY_STRUCTURE_SIZE) { | ||
| return false; | ||
| } | ||
| for (int index = 0; index < scalabilityStructureCount; index++) { | ||
| width = payload.readUnsignedShort(); | ||
| height = payload.readUnsignedShort(); | ||
| } | ||
| } | ||
|
|
||
| // Checks G bit, skips all additional temporal layers. | ||
| if ((scalabilityStructure & 0x08) != 0) { | ||
| // Reads N_G. | ||
| int numOfPicInPictureGroup = payload.readUnsignedByte(); | ||
| if (payload.bytesLeft() < numOfPicInPictureGroup) { | ||
| return false; | ||
| } | ||
|
|
||
| for (int picIndex = 0; picIndex < numOfPicInPictureGroup; picIndex++) { | ||
| int picture = payload.readUnsignedShort(); | ||
| int referenceIndices = (picture & 0x0C) >> 2; | ||
| if (payload.bytesLeft() < referenceIndices) { | ||
| return false; | ||
| } | ||
| // Ignore Reference indices. | ||
| payload.skipBytes(referenceIndices); | ||
| } | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
|
|
||
| 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); | ||
| } | ||
| } |