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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.audio;
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.Util;
import java.nio.ByteBuffer;
/**
* An {@link AudioProcessor} that converts high resolution PCM audio to 32-bit float. The following
* encodings are supported as input:
*
* <ul>
* <li>{@link C#ENCODING_PCM_24BIT}
* <li>{@link C#ENCODING_PCM_32BIT}
* <li>{@link C#ENCODING_PCM_FLOAT} ({@link #isActive()} will return {@code false})
* </ul>
*/
/* package */ final class FloatResamplingAudioProcessor extends BaseAudioProcessor {
private static final int FLOAT_NAN_AS_INT = Float.floatToIntBits(Float.NaN);
private static final double PCM_32_BIT_INT_TO_PCM_32_BIT_FLOAT_FACTOR = 1.0 / 0x7FFFFFFF;
@Override
public AudioFormat onConfigure(AudioFormat inputAudioFormat)
throws UnhandledAudioFormatException {
@C.PcmEncoding int encoding = inputAudioFormat.encoding;
if (!Util.isEncodingHighResolutionPcm(encoding)) {
throw new UnhandledAudioFormatException(inputAudioFormat);
}
return encoding != C.ENCODING_PCM_FLOAT
? new AudioFormat(
inputAudioFormat.sampleRate, inputAudioFormat.channelCount, C.ENCODING_PCM_FLOAT)
: AudioFormat.NOT_SET;
}
@Override
public void queueInput(ByteBuffer inputBuffer) {
int position = inputBuffer.position();
int limit = inputBuffer.limit();
int size = limit - position;
ByteBuffer buffer;
switch (inputAudioFormat.encoding) {
case C.ENCODING_PCM_24BIT:
buffer = replaceOutputBuffer((size / 3) * 4);
for (int i = position; i < limit; i += 3) {
int pcm32BitInteger =
((inputBuffer.get(i) & 0xFF) << 8)
| ((inputBuffer.get(i + 1) & 0xFF) << 16)
| ((inputBuffer.get(i + 2) & 0xFF) << 24);
writePcm32BitFloat(pcm32BitInteger, buffer);
}
break;
case C.ENCODING_PCM_32BIT:
buffer = replaceOutputBuffer(size);
for (int i = position; i < limit; i += 4) {
int pcm32BitInteger =
(inputBuffer.get(i) & 0xFF)
| ((inputBuffer.get(i + 1) & 0xFF) << 8)
| ((inputBuffer.get(i + 2) & 0xFF) << 16)
| ((inputBuffer.get(i + 3) & 0xFF) << 24);
writePcm32BitFloat(pcm32BitInteger, buffer);
}
break;
case C.ENCODING_PCM_8BIT:
case C.ENCODING_PCM_16BIT:
case C.ENCODING_PCM_16BIT_BIG_ENDIAN:
case C.ENCODING_PCM_FLOAT:
case C.ENCODING_INVALID:
case Format.NO_VALUE:
default:
// Never happens.
throw new IllegalStateException();
}
inputBuffer.position(inputBuffer.limit());
buffer.flip();
}
/**
* Converts the provided 32-bit integer to a 32-bit float value and writes it to {@code buffer}.
*
* @param pcm32BitInt The 32-bit integer value to convert to 32-bit float in [-1.0, 1.0].
* @param buffer The output buffer.
*/
private static void writePcm32BitFloat(int pcm32BitInt, ByteBuffer buffer) {
float pcm32BitFloat = (float) (PCM_32_BIT_INT_TO_PCM_32_BIT_FLOAT_FACTOR * pcm32BitInt);
int floatBits = Float.floatToIntBits(pcm32BitFloat);
if (floatBits == FLOAT_NAN_AS_INT) {
floatBits = Float.floatToIntBits((float) 0.0);
}
buffer.putInt(floatBits);
}
}
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