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/*
* Copyright (C) 2017 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.audio;
import androidx.annotation.Nullable;
import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions;
import java.nio.ByteBuffer;
/**
* An {@link AudioProcessor} that applies a mapping from input channels onto specified output
* channels. This can be used to reorder, duplicate or discard channels.
*/
@SuppressWarnings("nullness:initialization.fields.uninitialized")
/* package */ final class ChannelMappingAudioProcessor extends BaseAudioProcessor {
@Nullable private int[] pendingOutputChannels;
@Nullable private int[] outputChannels;
/**
* Resets the channel mapping. After calling this method, call {@link #configure(AudioFormat)} to
* start using the new channel map.
*
* @param outputChannels The mapping from input to output channel indices, or {@code null} to
* leave the input unchanged.
* @see AudioSink#configure(int, int, int, int, int[], int, int)
*/
public void setChannelMap(@Nullable int[] outputChannels) {
pendingOutputChannels = outputChannels;
}
@Override
public AudioFormat onConfigure(AudioFormat inputAudioFormat)
throws UnhandledAudioFormatException {
@Nullable int[] outputChannels = pendingOutputChannels;
if (outputChannels == null) {
return AudioFormat.NOT_SET;
}
if (inputAudioFormat.encoding != C.ENCODING_PCM_16BIT) {
throw new UnhandledAudioFormatException(inputAudioFormat);
}
boolean active = inputAudioFormat.channelCount != outputChannels.length;
for (int i = 0; i < outputChannels.length; i++) {
int channelIndex = outputChannels[i];
if (channelIndex >= inputAudioFormat.channelCount) {
throw new UnhandledAudioFormatException(inputAudioFormat);
}
active |= (channelIndex != i);
}
return active
? new AudioFormat(inputAudioFormat.sampleRate, outputChannels.length, C.ENCODING_PCM_16BIT)
: AudioFormat.NOT_SET;
}
@Override
public void queueInput(ByteBuffer inputBuffer) {
int[] outputChannels = Assertions.checkNotNull(this.outputChannels);
int position = inputBuffer.position();
int limit = inputBuffer.limit();
int frameCount = (limit - position) / inputAudioFormat.bytesPerFrame;
int outputSize = frameCount * outputAudioFormat.bytesPerFrame;
ByteBuffer buffer = replaceOutputBuffer(outputSize);
while (position < limit) {
for (int channelIndex : outputChannels) {
buffer.putShort(inputBuffer.getShort(position + 2 * channelIndex));
}
position += inputAudioFormat.bytesPerFrame;
}
inputBuffer.position(limit);
buffer.flip();
}
@Override
protected void onFlush() {
outputChannels = pendingOutputChannels;
}
@Override
protected void onReset() {
outputChannels = null;
pendingOutputChannels = null;
}
}
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