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/*
* Copyright (C) 2020 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 "SampleBuffer.h"
// Resampler Includes
#include <resampler/MultiChannelResampler.h>
#include "wav/WavStreamReader.h"
using namespace resampler;
namespace iolib {
void SampleBuffer::loadSampleData(parselib::WavStreamReader* reader) {
// Although we read this in, at this time we know a-priori that the data is mono
mAudioProperties.channelCount = reader->getNumChannels();
mAudioProperties.sampleRate = reader->getSampleRate();
reader->positionToAudio();
mNumSamples = reader->getNumSampleFrames() * reader->getNumChannels();
mSampleData = new float[mNumSamples];
reader->getDataFloat(mSampleData, reader->getNumSampleFrames());
}
void SampleBuffer::unloadSampleData() {
if (mSampleData != nullptr) {
delete[] mSampleData;
mSampleData = nullptr;
}
mNumSamples = 0;
}
class ResampleBlock {
public:
int32_t mSampleRate;
float* mBuffer;
int32_t mNumFrames;
};
void resampleData(const ResampleBlock& input, ResampleBlock* output, int numChannels) {
// Calculate output buffer size
double temp =
((double)input.mNumFrames * (double)output->mSampleRate) / (double)input.mSampleRate;
// round up
int32_t numOutFrames = (int32_t)(temp + 0.5);
// We iterate thousands of times through the loop. Roundoff error could accumulate
// so add a few more frames for padding
numOutFrames += 8;
MultiChannelResampler *resampler = MultiChannelResampler::make(
numChannels, // channel count
input.mSampleRate, // input sampleRate
output->mSampleRate, // output sampleRate
MultiChannelResampler::Quality::Medium); // conversion quality
float *inputBuffer = input.mBuffer;; // multi-channel buffer to be consumed
float *outputBuffer = new float[numOutFrames]; // multi-channel buffer to be filled
output->mBuffer = outputBuffer;
int numOutputFrames = 0;
int inputFramesLeft = input.mNumFrames;
while (inputFramesLeft > 0) {
if(resampler->isWriteNeeded()) {
resampler->writeNextFrame(inputBuffer);
inputBuffer += numChannels;
inputFramesLeft--;
} else {
resampler->readNextFrame(outputBuffer);
outputBuffer += numChannels;
numOutputFrames++;
}
}
output->mNumFrames = numOutputFrames;
delete resampler;
}
void SampleBuffer::resampleData(int sampleRate) {
if (mAudioProperties.sampleRate == sampleRate) {
// nothing to do
return;
}
ResampleBlock inputBlock;
inputBlock.mBuffer = mSampleData;
inputBlock.mNumFrames = mNumSamples;
inputBlock.mSampleRate = mAudioProperties.sampleRate;
ResampleBlock outputBlock;
outputBlock.mSampleRate = sampleRate;
iolib::resampleData(inputBlock, &outputBlock, mAudioProperties.channelCount);
// delete previous samples
delete[] mSampleData;
// install the resampled data
mSampleData = outputBlock.mBuffer;
mNumSamples = outputBlock.mNumFrames;
mAudioProperties.sampleRate = outputBlock.mSampleRate;
}
} // namespace iolib
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