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Merge pull request #162 from ittiam-systems:rtp-mp4a-latm
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180
...ry/rtsp/src/main/java/com/google/android/exoplayer2/source/rtsp/reader/RtpMp4aReader.java
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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; | ||
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import static com.google.android.exoplayer2.source.rtsp.reader.RtpReaderUtils.toSampleTimeUs; | ||
import static com.google.android.exoplayer2.util.Assertions.checkArgument; | ||
import static com.google.android.exoplayer2.util.Assertions.checkNotNull; | ||
import static com.google.android.exoplayer2.util.Assertions.checkState; | ||
import static com.google.android.exoplayer2.util.Assertions.checkStateNotNull; | ||
import static com.google.android.exoplayer2.util.Util.castNonNull; | ||
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import androidx.annotation.Nullable; | ||
import com.google.android.exoplayer2.C; | ||
import com.google.android.exoplayer2.ParserException; | ||
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.ParsableBitArray; | ||
import com.google.android.exoplayer2.util.ParsableByteArray; | ||
import com.google.android.exoplayer2.util.Util; | ||
import com.google.common.collect.ImmutableMap; | ||
import org.checkerframework.checker.nullness.qual.MonotonicNonNull; | ||
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/** | ||
* Parses an MP4A-LATM byte stream carried on RTP packets, and extracts MP4A-LATM Access Units. | ||
* | ||
* <p>Refer to RFC3016 for more details. The LATM byte stream format is defined in ISO/IEC14496-3. | ||
*/ | ||
/* package */ final class RtpMp4aReader implements RtpPayloadReader { | ||
private static final String TAG = "RtpMp4aReader"; | ||
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private static final String PARAMETER_MP4A_CONFIG = "config"; | ||
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private final RtpPayloadFormat payloadFormat; | ||
private final int numberOfSubframes; | ||
private @MonotonicNonNull TrackOutput trackOutput; | ||
private long firstReceivedTimestamp; | ||
private int previousSequenceNumber; | ||
/** The combined size of a sample that is fragmented into multiple subFrames. */ | ||
private int fragmentedSampleSizeBytes; | ||
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private long startTimeOffsetUs; | ||
private long fragmentedSampleTimeUs; | ||
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/** | ||
* Creates an instance. | ||
* | ||
* @throws IllegalArgumentException If {@link RtpPayloadFormat payloadFormat} is malformed. | ||
*/ | ||
public RtpMp4aReader(RtpPayloadFormat payloadFormat) { | ||
this.payloadFormat = payloadFormat; | ||
try { | ||
numberOfSubframes = getNumOfSubframesFromMpeg4AudioConfig(payloadFormat.fmtpParameters); | ||
} catch (ParserException e) { | ||
throw new IllegalArgumentException(e); | ||
} | ||
firstReceivedTimestamp = C.TIME_UNSET; | ||
previousSequenceNumber = C.INDEX_UNSET; | ||
fragmentedSampleSizeBytes = 0; | ||
// The start time offset must be 0 until the first seek. | ||
startTimeOffsetUs = 0; | ||
fragmentedSampleTimeUs = C.TIME_UNSET; | ||
} | ||
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@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) { | ||
checkState(firstReceivedTimestamp == C.TIME_UNSET); | ||
firstReceivedTimestamp = timestamp; | ||
} | ||
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@Override | ||
public void consume( | ||
ParsableByteArray data, long timestamp, int sequenceNumber, boolean rtpMarker) { | ||
checkStateNotNull(trackOutput); | ||
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int expectedSequenceNumber = RtpPacket.getNextSequenceNumber(previousSequenceNumber); | ||
if (fragmentedSampleSizeBytes > 0 && expectedSequenceNumber < sequenceNumber) { | ||
outputSampleMetadataForFragmentedPackets(); | ||
} | ||
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for (int subFrameIndex = 0; subFrameIndex < numberOfSubframes; subFrameIndex++) { | ||
int sampleLength = 0; | ||
// Implements PayloadLengthInfo() in ISO/IEC14496-3 Chapter 1.7.3.1, it only supports one | ||
// program and one layer. Each subframe starts with a variable length encoding. | ||
while (data.getPosition() < data.limit()) { | ||
int payloadMuxLength = data.readUnsignedByte(); | ||
sampleLength += payloadMuxLength; | ||
if (payloadMuxLength != 0xff) { | ||
break; | ||
} | ||
} | ||
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trackOutput.sampleData(data, sampleLength); | ||
fragmentedSampleSizeBytes += sampleLength; | ||
} | ||
fragmentedSampleTimeUs = | ||
toSampleTimeUs( | ||
startTimeOffsetUs, timestamp, firstReceivedTimestamp, payloadFormat.clockRate); | ||
if (rtpMarker) { | ||
outputSampleMetadataForFragmentedPackets(); | ||
} | ||
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. | ||
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/** | ||
* Parses an MPEG-4 Audio Stream Mux configuration, as defined in ISO/IEC14496-3. | ||
* | ||
* <p>FMTP attribute {@code config} contains the MPEG-4 Audio Stream Mux configuration. | ||
* | ||
* @param fmtpAttributes The format parameters, mapped from the SDP FMTP attribute. | ||
* @return The number of subframes that is carried in each RTP packet. | ||
*/ | ||
private static int getNumOfSubframesFromMpeg4AudioConfig( | ||
ImmutableMap<String, String> fmtpAttributes) throws ParserException { | ||
@Nullable String configInput = fmtpAttributes.get(PARAMETER_MP4A_CONFIG); | ||
int numberOfSubframes = 0; | ||
if (configInput != null && configInput.length() % 2 == 0) { | ||
byte[] configBuffer = Util.getBytesFromHexString(configInput); | ||
ParsableBitArray scratchBits = new ParsableBitArray(configBuffer); | ||
int audioMuxVersion = scratchBits.readBits(1); | ||
if (audioMuxVersion == 0) { | ||
checkArgument(scratchBits.readBits(1) == 1, "Only supports allStreamsSameTimeFraming."); | ||
numberOfSubframes = scratchBits.readBits(6); | ||
checkArgument(scratchBits.readBits(4) == 0, "Only suppors one program."); | ||
checkArgument(scratchBits.readBits(3) == 0, "Only suppors one layer."); | ||
} else { | ||
throw ParserException.createForMalformedDataOfUnknownType( | ||
"unsupported audio mux version: " + audioMuxVersion, null); | ||
} | ||
} | ||
// ISO/IEC14496-3 Chapter 1.7.3.2.3: The minimum value is 0 indicating 1 subframe. | ||
return numberOfSubframes + 1; | ||
} | ||
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/** | ||
* Outputs sample metadata. | ||
* | ||
* <p>Call this method only after receiving the end of an MPEG4 partition. | ||
*/ | ||
private void outputSampleMetadataForFragmentedPackets() { | ||
checkNotNull(trackOutput) | ||
.sampleMetadata( | ||
fragmentedSampleTimeUs, | ||
C.BUFFER_FLAG_KEY_FRAME, | ||
fragmentedSampleSizeBytes, | ||
/* offset= */ 0, | ||
/* cryptoData= */ null); | ||
fragmentedSampleSizeBytes = 0; | ||
fragmentedSampleTimeUs = C.TIME_UNSET; | ||
} | ||
} |
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