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/*
* Copyright (C) 2018 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 org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.ts;
import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.BinarySearchSeeker;
import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.ExtractorInput;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.TimestampAdjuster;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
import java.io.IOException;
/**
* A seeker that supports seeking within TS stream using binary search.
*
* <p>This seeker uses the first and last PCR values within the stream, as well as the stream
* duration to interpolate the PCR value of the seeking position. Then it performs binary search
* within the stream to find a packets whose PCR value is within {@link #SEEK_TOLERANCE_US} from the
* target PCR.
*/
/* package */ final class TsBinarySearchSeeker extends BinarySearchSeeker {
private static final long SEEK_TOLERANCE_US = 100_000;
private static final int MINIMUM_SEARCH_RANGE_BYTES = 5 * TsExtractor.TS_PACKET_SIZE;
private static final int TIMESTAMP_SEARCH_BYTES = 600 * TsExtractor.TS_PACKET_SIZE;
public TsBinarySearchSeeker(
TimestampAdjuster pcrTimestampAdjuster, long streamDurationUs, long inputLength, int pcrPid) {
super(
new DefaultSeekTimestampConverter(),
new TsPcrSeeker(pcrPid, pcrTimestampAdjuster),
streamDurationUs,
/* floorTimePosition= */ 0,
/* ceilingTimePosition= */ streamDurationUs + 1,
/* floorBytePosition= */ 0,
/* ceilingBytePosition= */ inputLength,
/* approxBytesPerFrame= */ TsExtractor.TS_PACKET_SIZE,
MINIMUM_SEARCH_RANGE_BYTES);
}
/**
* A {@link TimestampSeeker} implementation that looks for a given PCR timestamp at a given
* position in a TS stream.
*
* <p>Given a PCR timestamp, and a position within a TS stream, this seeker will peek up to {@link
* #TIMESTAMP_SEARCH_BYTES} from that stream position, look for all packets with PID equal to
* PCR_PID, and then compare the PCR timestamps (if available) of these packets to the target
* timestamp.
*/
private static final class TsPcrSeeker implements TimestampSeeker {
private final TimestampAdjuster pcrTimestampAdjuster;
private final ParsableByteArray packetBuffer;
private final int pcrPid;
public TsPcrSeeker(int pcrPid, TimestampAdjuster pcrTimestampAdjuster) {
this.pcrPid = pcrPid;
this.pcrTimestampAdjuster = pcrTimestampAdjuster;
packetBuffer = new ParsableByteArray();
}
@Override
public TimestampSearchResult searchForTimestamp(ExtractorInput input, long targetTimestamp)
throws IOException, InterruptedException {
long inputPosition = input.getPosition();
int bytesToSearch = (int) Math.min(TIMESTAMP_SEARCH_BYTES, input.getLength() - inputPosition);
packetBuffer.reset(bytesToSearch);
input.peekFully(packetBuffer.data, /* offset= */ 0, bytesToSearch);
return searchForPcrValueInBuffer(packetBuffer, targetTimestamp, inputPosition);
}
private TimestampSearchResult searchForPcrValueInBuffer(
ParsableByteArray packetBuffer, long targetPcrTimeUs, long bufferStartOffset) {
int limit = packetBuffer.limit();
long startOfLastPacketPosition = C.POSITION_UNSET;
long endOfLastPacketPosition = C.POSITION_UNSET;
long lastPcrTimeUsInRange = C.TIME_UNSET;
while (packetBuffer.bytesLeft() >= TsExtractor.TS_PACKET_SIZE) {
int startOfPacket =
TsUtil.findSyncBytePosition(packetBuffer.data, packetBuffer.getPosition(), limit);
int endOfPacket = startOfPacket + TsExtractor.TS_PACKET_SIZE;
if (endOfPacket > limit) {
break;
}
long pcrValue = TsUtil.readPcrFromPacket(packetBuffer, startOfPacket, pcrPid);
if (pcrValue != C.TIME_UNSET) {
long pcrTimeUs = pcrTimestampAdjuster.adjustTsTimestamp(pcrValue);
if (pcrTimeUs > targetPcrTimeUs) {
if (lastPcrTimeUsInRange == C.TIME_UNSET) {
// First PCR timestamp is already over target.
return TimestampSearchResult.overestimatedResult(pcrTimeUs, bufferStartOffset);
} else {
// Last PCR timestamp < target timestamp < this timestamp.
return TimestampSearchResult.targetFoundResult(
bufferStartOffset + startOfLastPacketPosition);
}
} else if (pcrTimeUs + SEEK_TOLERANCE_US > targetPcrTimeUs) {
long startOfPacketInStream = bufferStartOffset + startOfPacket;
return TimestampSearchResult.targetFoundResult(startOfPacketInStream);
}
lastPcrTimeUsInRange = pcrTimeUs;
startOfLastPacketPosition = startOfPacket;
}
packetBuffer.setPosition(endOfPacket);
endOfLastPacketPosition = endOfPacket;
}
if (lastPcrTimeUsInRange != C.TIME_UNSET) {
long endOfLastPacketPositionInStream = bufferStartOffset + endOfLastPacketPosition;
return TimestampSearchResult.underestimatedResult(
lastPcrTimeUsInRange, endOfLastPacketPositionInStream);
} else {
return TimestampSearchResult.NO_TIMESTAMP_IN_RANGE_RESULT;
}
}
@Override
public void onSeekFinished() {
packetBuffer.reset(Util.EMPTY_BYTE_ARRAY);
}
}
}
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