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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 androidx.annotation.VisibleForTesting;
import org.mozilla.thirdparty.com.google.android.exoplayer2.Format;
import org.mozilla.thirdparty.com.google.android.exoplayer2.ParserException;
import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.VorbisUtil;
import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.VorbisUtil.Mode;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.MimeTypes;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
import java.io.IOException;
import java.util.ArrayList;
/**
* {@link StreamReader} to extract Vorbis data out of Ogg byte stream.
*/
/* package */ final class VorbisReader extends StreamReader {
private VorbisSetup vorbisSetup;
private int previousPacketBlockSize;
private boolean seenFirstAudioPacket;
private VorbisUtil.VorbisIdHeader vorbisIdHeader;
private VorbisUtil.CommentHeader commentHeader;
public static boolean verifyBitstreamType(ParsableByteArray data) {
try {
return VorbisUtil.verifyVorbisHeaderCapturePattern(0x01, data, true);
} catch (ParserException e) {
return false;
}
}
@Override
protected void reset(boolean headerData) {
super.reset(headerData);
if (headerData) {
vorbisSetup = null;
vorbisIdHeader = null;
commentHeader = null;
}
previousPacketBlockSize = 0;
seenFirstAudioPacket = false;
}
@Override
protected void onSeekEnd(long currentGranule) {
super.onSeekEnd(currentGranule);
seenFirstAudioPacket = currentGranule != 0;
previousPacketBlockSize = vorbisIdHeader != null ? vorbisIdHeader.blockSize0 : 0;
}
@Override
protected long preparePayload(ParsableByteArray packet) {
// if this is not an audio packet...
if ((packet.data[0] & 0x01) == 1) {
return -1;
}
// ... we need to decode the block size
int packetBlockSize = decodeBlockSize(packet.data[0], vorbisSetup);
// a packet contains samples produced from overlapping the previous and current frame data
// (https://www.xiph.org/vorbis/doc/Vorbis_I_spec.html#x1-350001.3.2)
int samplesInPacket = seenFirstAudioPacket ? (packetBlockSize + previousPacketBlockSize) / 4
: 0;
// codec expects the number of samples appended to audio data
appendNumberOfSamples(packet, samplesInPacket);
// update state in members for next iteration
seenFirstAudioPacket = true;
previousPacketBlockSize = packetBlockSize;
return samplesInPacket;
}
@Override
protected boolean readHeaders(ParsableByteArray packet, long position, SetupData setupData)
throws IOException, InterruptedException {
if (vorbisSetup != null) {
return false;
}
vorbisSetup = readSetupHeaders(packet);
if (vorbisSetup == null) {
return true;
}
ArrayList<byte[]> codecInitialisationData = new ArrayList<>();
codecInitialisationData.add(vorbisSetup.idHeader.data);
codecInitialisationData.add(vorbisSetup.setupHeaderData);
setupData.format = Format.createAudioSampleFormat(null, MimeTypes.AUDIO_VORBIS, null,
this.vorbisSetup.idHeader.bitrateNominal, Format.NO_VALUE,
this.vorbisSetup.idHeader.channels, (int) this.vorbisSetup.idHeader.sampleRate,
codecInitialisationData, null, 0, null);
return true;
}
@VisibleForTesting
/* package */ VorbisSetup readSetupHeaders(ParsableByteArray scratch) throws IOException {
if (vorbisIdHeader == null) {
vorbisIdHeader = VorbisUtil.readVorbisIdentificationHeader(scratch);
return null;
}
if (commentHeader == null) {
commentHeader = VorbisUtil.readVorbisCommentHeader(scratch);
return null;
}
// the third packet contains the setup header
byte[] setupHeaderData = new byte[scratch.limit()];
// raw data of vorbis setup header has to be passed to decoder as CSD buffer #2
System.arraycopy(scratch.data, 0, setupHeaderData, 0, scratch.limit());
// partially decode setup header to get the modes
Mode[] modes = VorbisUtil.readVorbisModes(scratch, vorbisIdHeader.channels);
// we need the ilog of modes all the time when extracting, so we compute it once
int iLogModes = VorbisUtil.iLog(modes.length - 1);
return new VorbisSetup(vorbisIdHeader, commentHeader, setupHeaderData, modes, iLogModes);
}
/**
* Reads an int of {@code length} bits from {@code src} starting at {@code
* leastSignificantBitIndex}.
*
* @param src the {@code byte} to read from.
* @param length the length in bits of the int to read.
* @param leastSignificantBitIndex the index of the least significant bit of the int to read.
* @return the int value read.
*/
@VisibleForTesting
/* package */ static int readBits(byte src, int length, int leastSignificantBitIndex) {
return (src >> leastSignificantBitIndex) & (255 >>> (8 - length));
}
@VisibleForTesting
/* package */ static void appendNumberOfSamples(
ParsableByteArray buffer, long packetSampleCount) {
buffer.setLimit(buffer.limit() + 4);
// The vorbis decoder expects the number of samples in the packet
// to be appended to the audio data as an int32
buffer.data[buffer.limit() - 4] = (byte) (packetSampleCount & 0xFF);
buffer.data[buffer.limit() - 3] = (byte) ((packetSampleCount >>> 8) & 0xFF);
buffer.data[buffer.limit() - 2] = (byte) ((packetSampleCount >>> 16) & 0xFF);
buffer.data[buffer.limit() - 1] = (byte) ((packetSampleCount >>> 24) & 0xFF);
}
private static int decodeBlockSize(byte firstByteOfAudioPacket, VorbisSetup vorbisSetup) {
// read modeNumber (https://www.xiph.org/vorbis/doc/Vorbis_I_spec.html#x1-730004.3.1)
int modeNumber = readBits(firstByteOfAudioPacket, vorbisSetup.iLogModes, 1);
int currentBlockSize;
if (!vorbisSetup.modes[modeNumber].blockFlag) {
currentBlockSize = vorbisSetup.idHeader.blockSize0;
} else {
currentBlockSize = vorbisSetup.idHeader.blockSize1;
}
return currentBlockSize;
}
/**
* Class to hold all data read from Vorbis setup headers.
*/
/* package */ static final class VorbisSetup {
public final VorbisUtil.VorbisIdHeader idHeader;
public final VorbisUtil.CommentHeader commentHeader;
public final byte[] setupHeaderData;
public final Mode[] modes;
public final int iLogModes;
public VorbisSetup(VorbisUtil.VorbisIdHeader idHeader, VorbisUtil.CommentHeader
commentHeader, byte[] setupHeaderData, Mode[] modes, int iLogModes) {
this.idHeader = idHeader;
this.commentHeader = commentHeader;
this.setupHeaderData = setupHeaderData;
this.modes = modes;
this.iLogModes = iLogModes;
}
}
}
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