Add support for RTSP H263 #63
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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 androidx.media3.exoplayer.rtsp.reader; | ||
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| import static androidx.media3.common.util.Assertions.checkStateNotNull; | ||
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| 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; | ||
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| /** | ||
| * Parses a H263 byte stream carried on RTP packets, and extracts H263 frames as defined in RFC4629. | ||
| */ | ||
| /* package */ final class RtpH263Reader implements RtpPayloadReader { | ||
| private static final String TAG = "RtpH263Reader"; | ||
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| private static final long MEDIA_CLOCK_FREQUENCY = 90_000; | ||
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| /** I-frame VOP unit type. */ | ||
| private static final int I_VOP = 0; | ||
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| private static final int PICTURE_START_CODE = 128; | ||
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| private final RtpPayloadFormat payloadFormat; | ||
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| private @MonotonicNonNull TrackOutput trackOutput; | ||
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| /** | ||
| * 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 int previousSequenceNumber; | ||
| /** The combined size of a sample that is fragmented into multiple RTP packets. */ | ||
| private int fragmentedSampleSizeBytes; | ||
| private int width; | ||
| private int height; | ||
| private boolean isKeyFrame; | ||
| private boolean isOutputFormatSet; | ||
| private long startTimeOffsetUs; | ||
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| /** Creates an instance. */ | ||
| public RtpH263Reader(RtpPayloadFormat payloadFormat) { | ||
| this.payloadFormat = payloadFormat; | ||
| firstReceivedTimestamp = C.TIME_UNSET; | ||
| previousSequenceNumber = C.INDEX_UNSET; | ||
| fragmentedSampleSizeBytes = 0; | ||
| isKeyFrame = false; | ||
| isOutputFormatSet = false; | ||
| } | ||
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| @Override | ||
| public void createTracks(ExtractorOutput extractorOutput, int trackId) { | ||
| trackOutput = extractorOutput.track(trackId, C.TRACK_TYPE_VIDEO); | ||
| trackOutput.format(payloadFormat.format); | ||
| } | ||
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| @Override | ||
| public void onReceivingFirstPacket(long timestamp, int sequenceNumber) {} | ||
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| @Override | ||
| public void consume(ParsableByteArray data, long timestamp, int sequenceNumber, boolean rtpMarker) | ||
| throws ParserException { | ||
| checkStateNotNull(trackOutput); | ||
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| // H263 Header Payload Header, RFC4629 Section 5.1. | ||
| // 0 1 | ||
| // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 | ||
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ||
| // | RR |P|V| PLEN |PEBIT| | ||
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ||
| int currPosition = data.getPosition(); | ||
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| int header = data.readUnsignedShort(); | ||
| boolean pBitIsSet = ((header & 0x400) > 0); | ||
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| // Check if optional V (Video Redundancy Coding), PLEN or PEBIT is present, RFC4629 Section 5.1. | ||
| if ((header & 0x200) != 0 || (header & 0x1f8) != 0 || (header & 0x7) != 0) { | ||
| Log.w(TAG, "Packet discarded due to (VRC != 0) or (PLEN != 0) or (PEBIT != 0)"); | ||
|
There was a problem hiding this comment.
There was a problem hiding this comment. We are unable to find clip(s) which are having these special headers to add support and verify it. |
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| return; | ||
| } | ||
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| if (pBitIsSet) { | ||
| int startCodePayload = data.peekUnsignedByte() & 0xfc; | ||
| // Packets that begin with a Picture Start Code(100000). Refer RFC4629 Section 6.1. | ||
| if (startCodePayload < PICTURE_START_CODE) { | ||
| Log.w(TAG, "Picture start Code (PSC) missing, Dropping packet."); | ||
| return; | ||
| } | ||
| // Setting first two bytes of the start code. Refer RFC4629 Section 6.1.1. | ||
| data.getData()[currPosition] = 0; | ||
| data.getData()[currPosition + 1] = 0; | ||
| data.setPosition(currPosition); | ||
| } else { | ||
| // Check that this packet is in the sequence of the previous packet. | ||
| int expectedSequenceNumber = RtpPacket.getNextSequenceNumber(previousSequenceNumber); | ||
| if (sequenceNumber != expectedSequenceNumber) { | ||
| Log.w( | ||
| TAG, | ||
| Util.formatInvariant( | ||
| "Received RTP packet with unexpected sequence number. Expected: %d; received: %d." | ||
| + " Dropping packet.", | ||
| expectedSequenceNumber, sequenceNumber)); | ||
| return; | ||
| } | ||
| } | ||
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| if (fragmentedSampleSizeBytes == 0) { | ||
| parseVopHeader(data, isOutputFormatSet); | ||
| if (!isOutputFormatSet && isKeyFrame) { | ||
| 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; | ||
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| 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; | ||
| isKeyFrame = false; | ||
| } | ||
| previousSequenceNumber = sequenceNumber; | ||
| } | ||
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| @Override | ||
| public void seek(long nextRtpTimestamp, long timeUs) { | ||
| firstReceivedTimestamp = nextRtpTimestamp; | ||
| fragmentedSampleSizeBytes = 0; | ||
| startTimeOffsetUs = timeUs; | ||
| } | ||
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| // Internal methods. | ||
| /** | ||
| * Parses VOP Coding type and resolution. | ||
| */ | ||
| private void parseVopHeader(ParsableByteArray data, boolean gotResolution) { | ||
| // Picture Segment Packets (RFC4629 Section 6.1). | ||
| // Search for SHORT_VIDEO_START_MARKER (0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0). | ||
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| int currDataOffset = data.getPosition(); | ||
| /** | ||
| * Parsing short header. | ||
| * | ||
| * <p> These values are taken from <a | ||
| * href=https://cs.android.com/android/platform/superproject/+/master:frameworks/av/media/codecs/m4v_h263/dec/src/mp4def.h;l=115 | ||
| * >Android's software H263 decoder</a>. | ||
| */ | ||
| long shortHeader = data.readUnsignedInt(); | ||
|
There was a problem hiding this comment. what is the reason to name this There was a problem hiding this comment. Its taken from h263 decoder. Added link for the same in javaDoc. |
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| if (((shortHeader >> 10) & 0x3f) == 0x20) { | ||
| int header = data.peekUnsignedByte(); | ||
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| int vopType = ((header >> 1) & 0x1); | ||
| if (!gotResolution && vopType == I_VOP) { | ||
| /** | ||
| * Parsing resolution from source format. | ||
| * | ||
| * <p> These values are taken from <a | ||
| * href=https://cs.android.com/android/platform/superproject/+/master:frameworks/av/media/codecs/m4v_h263/dec/src/vop.cpp;l=1126 | ||
| * >Android's software H263 decoder</a>. | ||
| */ | ||
| int sourceFormat = ((header >> 2) & 0x07); | ||
| if (sourceFormat == 1) { | ||
| width = 128; | ||
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| height = 96; | ||
| } else { | ||
| width = (short) (176 << (sourceFormat - 2)); | ||
| height = (short) (144 << (sourceFormat - 2)); | ||
|
There was a problem hiding this comment. Can you explain a bit here? I'm particularly lost why the shift bits are derived from a There was a problem hiding this comment. https://cs.android.com/android/platform/superproject/+/master:frameworks/av/media/codecs/m4v_h263/dec/src/vop.cpp;l=1128. According to this logic : |
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| } | ||
| } | ||
| data.setPosition(currDataOffset); | ||
| isKeyFrame = (vopType == I_VOP ? true : false); | ||
| return; | ||
| } | ||
| data.setPosition(currDataOffset); | ||
| isKeyFrame = false; | ||
| } | ||
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| 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); | ||
| } | ||
| } | ||
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