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Merge pull request #35 from ittiam-systems:rtp-mpeg4
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148 changes: 148 additions & 0 deletions
148
...y/rtsp/src/main/java/com/google/android/exoplayer2/source/rtsp/reader/RtpMpeg4Reader.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,148 @@ | ||
| /* | ||
| * 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.checkStateNotNull; | ||
| import static com.google.android.exoplayer2.util.Util.castNonNull; | ||
|
|
||
| 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 com.google.common.primitives.Bytes; | ||
| import org.checkerframework.checker.nullness.qual.MonotonicNonNull; | ||
|
|
||
| /** | ||
| * Parses an MPEG4 byte stream carried on RTP packets, and extracts MPEG4 Access Units. Refer to | ||
| * RFC6416 for more details. | ||
| */ | ||
| /* package */ final class RtpMpeg4Reader implements RtpPayloadReader { | ||
| private static final String TAG = "RtpMpeg4Reader"; | ||
|
|
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| private static final long MEDIA_CLOCK_FREQUENCY = 90_000; | ||
|
|
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| /** VOP (Video Object Plane) unit type. */ | ||
| private static final int I_VOP = 0; | ||
|
|
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| private final RtpPayloadFormat payloadFormat; | ||
| private @MonotonicNonNull TrackOutput trackOutput; | ||
| private @C.BufferFlags int bufferFlags; | ||
|
|
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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; | ||
| private long startTimeOffsetUs; | ||
| private int sampleLength; | ||
|
|
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| /** Creates an instance. */ | ||
| public RtpMpeg4Reader(RtpPayloadFormat payloadFormat) { | ||
| this.payloadFormat = payloadFormat; | ||
| firstReceivedTimestamp = C.TIME_UNSET; | ||
| previousSequenceNumber = C.INDEX_UNSET; | ||
| sampleLength = 0; | ||
| } | ||
|
|
||
| @Override | ||
| public void createTracks(ExtractorOutput extractorOutput, int trackId) { | ||
| trackOutput = extractorOutput.track(trackId, C.TRACK_TYPE_VIDEO); | ||
| castNonNull(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) { | ||
| checkStateNotNull(trackOutput); | ||
| // Check that this packet is in the sequence of the previous packet. | ||
| if (previousSequenceNumber != C.INDEX_UNSET) { | ||
| 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)); | ||
| } | ||
| } | ||
|
|
||
| // Parse VOP Type and get the buffer flags | ||
| int limit = data.bytesLeft(); | ||
| trackOutput.sampleData(data, limit); | ||
| if (sampleLength == 0) { | ||
| bufferFlags = getBufferFlagsFromVop(data); | ||
| } | ||
| sampleLength += limit; | ||
|
|
||
| // RTP marker indicates the last packet carrying a VOP. | ||
| if (rtpMarker) { | ||
| if (firstReceivedTimestamp == C.TIME_UNSET) { | ||
| firstReceivedTimestamp = timestamp; | ||
| } | ||
|
|
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| long timeUs = toSampleUs(startTimeOffsetUs, timestamp, firstReceivedTimestamp); | ||
| trackOutput.sampleMetadata(timeUs, bufferFlags, sampleLength, 0, null); | ||
| sampleLength = 0; | ||
| } | ||
| previousSequenceNumber = sequenceNumber; | ||
| } | ||
|
|
||
| @Override | ||
| public void seek(long nextRtpTimestamp, long timeUs) { | ||
| firstReceivedTimestamp = nextRtpTimestamp; | ||
| startTimeOffsetUs = timeUs; | ||
| sampleLength = 0; | ||
| } | ||
|
|
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| // Internal methods. | ||
|
|
||
| /** | ||
| * Returns VOP (Video Object Plane) Coding type. | ||
| * | ||
| * <p>Sets {@link #bufferFlags} according to the VOP Coding type. | ||
| */ | ||
| private static @C.BufferFlags int getBufferFlagsFromVop(ParsableByteArray data) { | ||
| // search for VOP_START_CODE (00 00 01 B6) | ||
| byte[] inputData = data.getData(); | ||
| byte[] startCode = new byte[] {0x0, 0x0, 0x1, (byte) 0xB6}; | ||
| int vopStartCodePos = Bytes.indexOf(inputData, startCode); | ||
| if (vopStartCodePos != -1) { | ||
| data.setPosition(vopStartCodePos + 4); | ||
| int vopType = data.peekUnsignedByte() >> 6; | ||
| return vopType == I_VOP ? C.BUFFER_FLAG_KEY_FRAME : 0; | ||
| } | ||
| return 0; | ||
| } | ||
|
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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); | ||
| } | ||
| } |