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/*
* Copyright (C) 2016 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.ogg;
import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
import org.mozilla.thirdparty.com.google.android.exoplayer2.Format;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.MimeTypes;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* {@link StreamReader} to extract Opus data out of Ogg byte stream.
*/
/* package */ final class OpusReader extends StreamReader {
private static final int DEFAULT_SEEK_PRE_ROLL_SAMPLES = 3840;
/**
* Opus streams are always decoded at 48000 Hz.
*/
private static final int SAMPLE_RATE = 48000;
private static final int OPUS_CODE = 0x4f707573;
private static final byte[] OPUS_SIGNATURE = {'O', 'p', 'u', 's', 'H', 'e', 'a', 'd'};
private boolean headerRead;
public static boolean verifyBitstreamType(ParsableByteArray data) {
if (data.bytesLeft() < OPUS_SIGNATURE.length) {
return false;
}
byte[] header = new byte[OPUS_SIGNATURE.length];
data.readBytes(header, 0, OPUS_SIGNATURE.length);
return Arrays.equals(header, OPUS_SIGNATURE);
}
@Override
protected void reset(boolean headerData) {
super.reset(headerData);
if (headerData) {
headerRead = false;
}
}
@Override
protected long preparePayload(ParsableByteArray packet) {
return convertTimeToGranule(getPacketDurationUs(packet.data));
}
@Override
protected boolean readHeaders(ParsableByteArray packet, long position, SetupData setupData) {
if (!headerRead) {
byte[] metadata = Arrays.copyOf(packet.data, packet.limit());
int channelCount = metadata[9] & 0xFF;
int preskip = ((metadata[11] & 0xFF) << 8) | (metadata[10] & 0xFF);
List<byte[]> initializationData = new ArrayList<>(3);
initializationData.add(metadata);
putNativeOrderLong(initializationData, preskip);
putNativeOrderLong(initializationData, DEFAULT_SEEK_PRE_ROLL_SAMPLES);
setupData.format = Format.createAudioSampleFormat(null, MimeTypes.AUDIO_OPUS, null,
Format.NO_VALUE, Format.NO_VALUE, channelCount, SAMPLE_RATE, initializationData, null, 0,
null);
headerRead = true;
} else {
boolean headerPacket = packet.readInt() == OPUS_CODE;
packet.setPosition(0);
return headerPacket;
}
return true;
}
private void putNativeOrderLong(List<byte[]> initializationData, int samples) {
long ns = (samples * C.NANOS_PER_SECOND) / SAMPLE_RATE;
byte[] array = ByteBuffer.allocate(8).order(ByteOrder.nativeOrder()).putLong(ns).array();
initializationData.add(array);
}
/**
* Returns the duration of the given audio packet.
*
* @param packet Contains audio data.
* @return Returns the duration of the given audio packet.
*/
private long getPacketDurationUs(byte[] packet) {
int toc = packet[0] & 0xFF;
int frames;
switch (toc & 0x3) {
case 0:
frames = 1;
break;
case 1:
case 2:
frames = 2;
break;
default:
frames = packet[1] & 0x3F;
break;
}
int config = toc >> 3;
int length = config & 0x3;
if (config >= 16) {
length = 2500 << length;
} else if (config >= 12) {
length = 10000 << (length & 0x1);
} else if (length == 3) {
length = 60000;
} else {
length = 10000 << length;
}
return (long) frames * length;
}
}
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