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/*
* Copyright 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.
*/
#include "WaveFileWriter.h"
void WaveFileWriter::WaveFileWriter::write(float value) {
if (!mHeaderWritten) {
writeHeader();
}
if (mBitsPerSample == 24) {
writePCM24(value);
} else {
writePCM16(value);
}
}
void WaveFileWriter::write(float *buffer, int32_t startSample, int32_t numSamples) {
for (int32_t i = 0; i < numSamples; i++) {
write(buffer[startSample + i]);
}
}
void WaveFileWriter::writeIntLittle(int32_t n) {
writeByte(n);
writeByte(n >> 8);
writeByte(n >> 16);
writeByte(n >> 24);
}
void WaveFileWriter::writeShortLittle(int16_t n) {
writeByte(n);
writeByte(n >> 8);
}
void WaveFileWriter::writeFormatChunk() {
int32_t bytesPerSample = (mBitsPerSample + 7) / 8;
writeByte('f');
writeByte('m');
writeByte('t');
writeByte(' ');
writeIntLittle(16); // chunk size
writeShortLittle(WAVE_FORMAT_PCM);
writeShortLittle((int16_t) mSamplesPerFrame);
writeIntLittle(mFrameRate);
// bytes/second
writeIntLittle(mFrameRate * mSamplesPerFrame * bytesPerSample);
// block align
writeShortLittle((int16_t) (mSamplesPerFrame * bytesPerSample));
writeShortLittle((int16_t) mBitsPerSample);
}
int32_t WaveFileWriter::getDataSizeInBytes() {
if (mFrameCount <= 0) return INT32_MAX;
int64_t dataSize = ((int64_t)mFrameCount) * mSamplesPerFrame * mBitsPerSample / 8;
return (int32_t)std::min(dataSize, (int64_t)INT32_MAX);
}
void WaveFileWriter::writeDataChunkHeader() {
writeByte('d');
writeByte('a');
writeByte('t');
writeByte('a');
writeIntLittle(getDataSizeInBytes());
}
void WaveFileWriter::writeHeader() {
writeRiffHeader();
writeFormatChunk();
writeDataChunkHeader();
mHeaderWritten = true;
}
// Write lower 8 bits. Upper bits ignored.
void WaveFileWriter::writeByte(uint8_t b) {
mOutputStream->write(b);
mBytesWritten += 1;
}
void WaveFileWriter::writePCM24(float value) {
// Offset before casting so that we can avoid using floor().
// Also round by adding 0.5 so that very small signals go to zero.
float temp = (PCM24_MAX * value) + 0.5 - PCM24_MIN;
int32_t sample = ((int) temp) + PCM24_MIN;
// clip to 24-bit range
if (sample > PCM24_MAX) {
sample = PCM24_MAX;
} else if (sample < PCM24_MIN) {
sample = PCM24_MIN;
}
// encode as little-endian
writeByte(sample); // little end
writeByte(sample >> 8); // middle
writeByte(sample >> 16); // big end
}
void WaveFileWriter::writePCM16(float value) {
// Offset before casting so that we can avoid using floor().
// Also round by adding 0.5 so that very small signals go to zero.
float temp = (INT16_MAX * value) + 0.5 - INT16_MIN;
int32_t sample = ((int) temp) + INT16_MIN;
if (sample > INT16_MAX) {
sample = INT16_MAX;
} else if (sample < INT16_MIN) {
sample = INT16_MIN;
}
writeByte(sample); // little end
writeByte(sample >> 8); // big end
}
void WaveFileWriter::writeRiffHeader() {
writeByte('R');
writeByte('I');
writeByte('F');
writeByte('F');
// Maximum size is not strictly correct but is commonly used
// when we do not know the final size.
const int kExtraHeaderBytes = 36;
int32_t dataSize = getDataSizeInBytes();
writeIntLittle((dataSize > (INT32_MAX - kExtraHeaderBytes))
? INT32_MAX
: dataSize + kExtraHeaderBytes);
writeByte('W');
writeByte('A');
writeByte('V');
writeByte('E');
}
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