RtpPcmReader.java
/*
* 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;
import static androidx.media3.common.util.Assertions.checkNotNull;
import static androidx.media3.exoplayer.rtsp.reader.RtpReaderUtils.toSampleTimeUs;
import android.util.Log;
import androidx.media3.common.C;
import androidx.media3.common.util.ParsableByteArray;
import androidx.media3.common.util.UnstableApi;
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;
/**
* Parses byte stream carried on RTP packets, and extracts PCM frames. Refer to RFC3551 for more
* details.
*/
@UnstableApi
/* package */ public final class RtpPcmReader implements RtpPayloadReader {
private static final String TAG = "RtpPcmReader";
private final RtpPayloadFormat payloadFormat;
private @MonotonicNonNull TrackOutput trackOutput;
private long firstReceivedTimestamp;
private long startTimeOffsetUs;
private int previousSequenceNumber;
public RtpPcmReader(RtpPayloadFormat payloadFormat) {
this.payloadFormat = payloadFormat;
firstReceivedTimestamp = C.TIME_UNSET;
// Start time offset must be 0 before the first seek.
startTimeOffsetUs = 0;
previousSequenceNumber = C.INDEX_UNSET;
}
@Override
public void createTracks(ExtractorOutput extractorOutput, int trackId) {
trackOutput = extractorOutput.track(trackId, C.TRACK_TYPE_AUDIO);
trackOutput.format(payloadFormat.format);
}
@Override
public void onReceivingFirstPacket(long timestamp, int sequenceNumber) {
firstReceivedTimestamp = timestamp;
}
@Override
public void consume(
ParsableByteArray data, long timestamp, int sequenceNumber, boolean rtpMarker) {
checkNotNull(trackOutput);
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.",
expectedSequenceNumber, sequenceNumber));
}
}
long sampleTimeUs =
toSampleTimeUs(
startTimeOffsetUs, timestamp, firstReceivedTimestamp, payloadFormat.clockRate);
int size = data.bytesLeft();
trackOutput.sampleData(data, size);
trackOutput.sampleMetadata(
sampleTimeUs, C.BUFFER_FLAG_KEY_FRAME, size, /* offset= */ 0, /* cryptoData= */ null);
previousSequenceNumber = sequenceNumber;
}
@Override
public void seek(long nextRtpTimestamp, long timeUs) {
// TODO(b/198620566) Rename firstReceivedTimestamp to timestampBase for all RtpPayloadReaders.
firstReceivedTimestamp = nextRtpTimestamp;
startTimeOffsetUs = timeUs;
}
}