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Parse channel count and sample rate from ALAC initialization data

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Also remove the "do we really need to do this" comment for AAC.
Parsing from codec specific data is likely to be more robust, so
I think we should continue to do it for formats where we've seen
this problem.

Issue: #6648
PiperOrigin-RevId: 280575466
This commit is contained in:
olly 2019-11-15 04:29:30 +00:00 committed by Oliver Woodman
parent 1345010e27
commit 2e0719b555
3 changed files with 81 additions and 11 deletions
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10
library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java
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@ -1114,8 +1114,8 @@ import java.util.List;
mimeType = mimeTypeAndInitializationData.first;
initializationData = mimeTypeAndInitializationData.second;
if (MimeTypes.AUDIO_AAC.equals(mimeType)) {
// TODO: Do we really need to do this? See [Internal: b/10903778]
// Update sampleRate and channelCount from the AudioSpecificConfig initialization data.
// Update sampleRate and channelCount from the AudioSpecificConfig initialization data,
// which is more reliable. See [Internal: b/10903778].
Pair<Integer, Integer> audioSpecificConfig =
CodecSpecificDataUtil.parseAacAudioSpecificConfig(initializationData);
sampleRate = audioSpecificConfig.first;
@ -1160,6 +1160,12 @@ import java.util.List;
initializationData = new byte[childAtomBodySize];
parent.setPosition(childPosition + Atom.FULL_HEADER_SIZE);
parent.readBytes(initializationData, /* offset= */ 0, childAtomBodySize);
// Update sampleRate and channelCount from the AudioSpecificConfig initialization data,
// which is more reliable. See https://github.com/google/ExoPlayer/pull/6629.
Pair<Integer, Integer> audioSpecificConfig =
CodecSpecificDataUtil.parseAlacAudioSpecificConfig(initializationData);
sampleRate = audioSpecificConfig.first;
channelCount = audioSpecificConfig.second;
}
childPosition += childAtomSize;
}

34
library/core/src/main/java/com/google/android/exoplayer2/util/CodecSpecificDataUtil.java
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@ -83,7 +83,7 @@ public final class CodecSpecificDataUtil {
private CodecSpecificDataUtil() {}
/**
* Parses an AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
* Parses an AAC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
*
* @param audioSpecificConfig A byte array containing the AudioSpecificConfig to parse.
* @return A pair consisting of the sample rate in Hz and the channel count.
@ -95,7 +95,7 @@ public final class CodecSpecificDataUtil {
}
/**
* Parses an AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
* Parses an AAC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
*
* @param bitArray A {@link ParsableBitArray} containing the AudioSpecificConfig to parse. The
* position is advanced to the end of the AudioSpecificConfig.
@ -104,8 +104,8 @@ public final class CodecSpecificDataUtil {
* @return A pair consisting of the sample rate in Hz and the channel count.
* @throws ParserException If the AudioSpecificConfig cannot be parsed as it's not supported.
*/
public static Pair<Integer, Integer> parseAacAudioSpecificConfig(ParsableBitArray bitArray,
boolean forceReadToEnd) throws ParserException {
public static Pair<Integer, Integer> parseAacAudioSpecificConfig(
ParsableBitArray bitArray, boolean forceReadToEnd) throws ParserException {
int audioObjectType = getAacAudioObjectType(bitArray);
int sampleRate = getAacSamplingFrequency(bitArray);
int channelConfiguration = bitArray.readBits(4);
@ -166,10 +166,10 @@ public final class CodecSpecificDataUtil {
* Builds a simple HE-AAC LC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
*
* @param sampleRate The sample rate in Hz.
* @param numChannels The number of channels.
* @param channelCount The channel count.
* @return The AudioSpecificConfig.
*/
public static byte[] buildAacLcAudioSpecificConfig(int sampleRate, int numChannels) {
public static byte[] buildAacLcAudioSpecificConfig(int sampleRate, int channelCount) {
int sampleRateIndex = C.INDEX_UNSET;
for (int i = 0; i < AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE.length; ++i) {
if (sampleRate == AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE[i]) {
@ -178,13 +178,13 @@ public final class CodecSpecificDataUtil {
}
int channelConfig = C.INDEX_UNSET;
for (int i = 0; i < AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE.length; ++i) {
if (numChannels == AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE[i]) {
if (channelCount == AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE[i]) {
channelConfig = i;
}
}
if (sampleRate == C.INDEX_UNSET || channelConfig == C.INDEX_UNSET) {
throw new IllegalArgumentException("Invalid sample rate or number of channels: "
+ sampleRate + ", " + numChannels);
throw new IllegalArgumentException(
"Invalid sample rate or number of channels: " + sampleRate + ", " + channelCount);
}
return buildAacAudioSpecificConfig(AUDIO_OBJECT_TYPE_AAC_LC, sampleRateIndex, channelConfig);
}
@ -205,6 +205,22 @@ public final class CodecSpecificDataUtil {
return specificConfig;
}
/**
* Parses an ALAC AudioSpecificConfig (i.e. an <a
* href="https://github.com/macosforge/alac/blob/master/ALACMagicCookieDescription.txt">ALACSpecificConfig</a>).
*
* @param audioSpecificConfig A byte array containing the AudioSpecificConfig to parse.
* @return A pair consisting of the sample rate in Hz and the channel count.
*/
public static Pair<Integer, Integer> parseAlacAudioSpecificConfig(byte[] audioSpecificConfig) {
ParsableByteArray byteArray = new ParsableByteArray(audioSpecificConfig);
byteArray.setPosition(9);
int channelCount = byteArray.readUnsignedByte();
byteArray.setPosition(20);
int sampleRate = byteArray.readUnsignedIntToInt();
return Pair.create(sampleRate, channelCount);
}
/**
* Builds an RFC 6381 AVC codec string using the provided parameters.
*

48
library/core/src/test/java/com/google/android/exoplayer2/util/CodecSpecificDataUtilTest.java Normal file
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@ -0,0 +1,48 @@
/*
* Copyright (C) 2019 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.util;
import static com.google.common.truth.Truth.assertThat;
import android.util.Pair;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import org.junit.Test;
import org.junit.runner.RunWith;
/** Unit test for {@link CodecSpecificDataUtil}. */
@RunWith(AndroidJUnit4.class)
public class CodecSpecificDataUtilTest {
@Test
public void parseAlacAudioSpecificConfig() {
byte[] alacSpecificConfig =
new byte[] {
0, 0, 16, 0, // frameLength
0, // compatibleVersion
16, // bitDepth
40, 10, 14, // tuning parameters
2, // numChannels = 2
0, 0, // maxRun
0, 0, 64, 4, // maxFrameBytes
0, 46, -32, 0, // avgBitRate
0, 1, 119, 0, // sampleRate = 96000
};
Pair<Integer, Integer> sampleRateAndChannelCount =
CodecSpecificDataUtil.parseAlacAudioSpecificConfig(alacSpecificConfig);
assertThat(sampleRateAndChannelCount.first).isEqualTo(96000);
assertThat(sampleRateAndChannelCount.second).isEqualTo(2);
}
}