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Merge pull request #53 from ittiam-systems:rtp_opus
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157
...ry/rtsp/src/main/java/com/google/android/exoplayer2/source/rtsp/reader/RtpOpusReader.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.Format; | ||
| import com.google.android.exoplayer2.audio.OpusUtil; | ||
| 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 java.util.List; | ||
| import org.checkerframework.checker.nullness.qual.MonotonicNonNull; | ||
|
|
||
| /** | ||
| * Parses an OPUS byte stream carried on RTP packets and extracts individual samples. Refer to | ||
| * RFC7845 for more details. | ||
| */ | ||
| /* package */ final class RtpOpusReader implements RtpPayloadReader { | ||
| private static final String TAG = "RtpOpusReader"; | ||
| /* Opus uses a fixed 48KHz media clock RFC7845 Section 4. */ | ||
| private static final long MEDIA_CLOCK_FREQUENCY = 48_000; | ||
|
|
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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 long startTimeOffsetUs; | ||
| private int previousSequenceNumber; | ||
| private boolean foundOpusIDHeader; | ||
| private boolean foundOpusCommentHeader; | ||
|
|
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| /** Creates an instance. */ | ||
| public RtpOpusReader(RtpPayloadFormat payloadFormat) { | ||
| this.payloadFormat = payloadFormat; | ||
| this.firstReceivedTimestamp = C.INDEX_UNSET; | ||
| this.previousSequenceNumber = C.INDEX_UNSET; | ||
| } | ||
|
|
||
| // RtpPayloadReader implementation. | ||
|
|
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| @Override | ||
| public void createTracks(ExtractorOutput extractorOutput, int trackId) { | ||
| trackOutput = extractorOutput.track(trackId, C.TRACK_TYPE_AUDIO); | ||
| trackOutput.format(payloadFormat.format); | ||
| } | ||
|
|
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| @Override | ||
| public void onReceivingFirstPacket(long timestamp, int sequenceNumber) { | ||
| this.firstReceivedTimestamp = timestamp; | ||
| } | ||
|
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| @Override | ||
| public void consume( | ||
| ParsableByteArray data, long timestamp, int sequenceNumber, boolean rtpMarker) { | ||
| checkStateNotNull(trackOutput); | ||
|
|
||
| /* RFC7845 Section 3. | ||
| * +---------+ +----------------+ +--------------------+ +----- | ||
| * |ID Header| | Comment Header | |Audio Data Packet 1 | | ... | ||
| * +---------+ +----------------+ +--------------------+ +----- | ||
| */ | ||
| if (!foundOpusIDHeader) { | ||
| validateOpusIdHeader(data); | ||
| List<byte[]> initializationData = OpusUtil.buildInitializationData(data.getData()); | ||
| Format.Builder formatBuilder = payloadFormat.format.buildUpon(); | ||
| formatBuilder.setInitializationData(initializationData); | ||
| trackOutput.format(formatBuilder.build()); | ||
| foundOpusIDHeader = true; | ||
| } else if (!foundOpusCommentHeader) { | ||
| // Comment Header RFC7845 Section 5.2. | ||
| int sampleSize = data.limit(); | ||
| checkArgument(sampleSize >= 8, "Comment Header has insufficient data"); | ||
| String header = data.readString(8); | ||
| checkArgument(header.equals("OpusTags"), "Comment Header should follow ID Header"); | ||
| foundOpusCommentHeader = true; | ||
| } 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.", | ||
| expectedSequenceNumber, sequenceNumber)); | ||
| } | ||
|
|
||
| // sending opus data. | ||
| int size = data.bytesLeft(); | ||
| trackOutput.sampleData(data, size); | ||
| long timeUs = toSampleTimeUs(startTimeOffsetUs, timestamp, firstReceivedTimestamp); | ||
| trackOutput.sampleMetadata( | ||
| timeUs, C.BUFFER_FLAG_KEY_FRAME, size, /* offset*/ 0, /* cryptoData*/ null); | ||
| } | ||
| previousSequenceNumber = sequenceNumber; | ||
| } | ||
|
|
||
| @Override | ||
| public void seek(long nextRtpTimestamp, long timeUs) { | ||
| firstReceivedTimestamp = nextRtpTimestamp; | ||
| startTimeOffsetUs = timeUs; | ||
| } | ||
|
|
||
| // Internal methods. | ||
|
|
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| /** | ||
| * Validates the OPUS ID Header at {@code data}'s current position, throws {@link | ||
| * IllegalArgumentException} if the header is invalid. | ||
| * | ||
| * <p>{@code data}'s position does not change after returning. | ||
| */ | ||
| private static void validateOpusIdHeader(ParsableByteArray data) { | ||
| int currPosition = data.getPosition(); | ||
| int sampleSize = data.limit(); | ||
| checkArgument(sampleSize > 18, "ID Header has insufficient data"); | ||
| String header = data.readString(8); | ||
| // Identification header RFC7845 Section 5.1. | ||
| checkArgument(header.equals("OpusHead"), "ID Header missing"); | ||
| checkArgument(data.readUnsignedByte() == 1, "version number must always be 1"); | ||
| data.setPosition(currPosition); | ||
| } | ||
|
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| /** Returns the correct sample time from RTP timestamp, accounting for the OPUS sampling rate. */ | ||
| private static long toSampleTimeUs( | ||
| 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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