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Merge pull request #162 from ittiam-systems:rtp-mp4a-latm
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...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; | ||
|
|
||
| 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; | ||
|
|
||
| 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; | ||
|
|
||
| /** | ||
| * 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; | ||
|
|
||
| private long startTimeOffsetUs; | ||
| private long fragmentedSampleTimeUs; | ||
|
|
||
| /** | ||
| * 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; | ||
| } | ||
|
|
||
| @Override | ||
| public void createTracks(ExtractorOutput extractorOutput, int trackId) { | ||
| trackOutput = extractorOutput.track(trackId, C.TRACK_TYPE_VIDEO); | ||
| castNonNull(trackOutput).format(payloadFormat.format); | ||
| } | ||
|
|
||
| @Override | ||
| public void onReceivingFirstPacket(long timestamp, int sequenceNumber) { | ||
| checkState(firstReceivedTimestamp == C.TIME_UNSET); | ||
| firstReceivedTimestamp = timestamp; | ||
| } | ||
|
|
||
| @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(); | ||
| } | ||
|
|
||
| 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; | ||
| } | ||
| } | ||
|
|
||
| trackOutput.sampleData(data, sampleLength); | ||
| fragmentedSampleSizeBytes += sampleLength; | ||
| } | ||
| fragmentedSampleTimeUs = | ||
| toSampleTimeUs( | ||
| startTimeOffsetUs, timestamp, firstReceivedTimestamp, payloadFormat.clockRate); | ||
| if (rtpMarker) { | ||
| outputSampleMetadataForFragmentedPackets(); | ||
| } | ||
| previousSequenceNumber = sequenceNumber; | ||
| } | ||
|
|
||
| @Override | ||
| public void seek(long nextRtpTimestamp, long timeUs) { | ||
| firstReceivedTimestamp = nextRtpTimestamp; | ||
| fragmentedSampleSizeBytes = 0; | ||
| startTimeOffsetUs = timeUs; | ||
| } | ||
|
|
||
| // Internal methods. | ||
|
|
||
| /** | ||
| * 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; | ||
| } | ||
|
|
||
| /** | ||
| * 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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