Function process

lib-src/soundtouch/source/SoundStretch/main.cpp:177–225

Processes the sound

// Processes the sound
static void process(SoundTouch *pSoundTouch, WavInFile *inFile, WavOutFile *outFile)
{
    int nSamples;
    int nChannels;
    int buffSizeSamples;
    SAMPLETYPE sampleBuffer[BUFF_SIZE];

    if ((inFile == NULL) || (outFile == NULL)) return;  // nothing to do.

    nChannels = (int)inFile->getNumChannels();
    assert(nChannels > 0);
    buffSizeSamples = BUFF_SIZE / nChannels;

    // Process samples read from the input file
    while (inFile->eof() == 0)
    {
        int num;

        // Read a chunk of samples from the input file
        num = inFile->read(sampleBuffer, BUFF_SIZE);
        nSamples = num / (int)inFile->getNumChannels();

        // Feed the samples into SoundTouch processor
        pSoundTouch->putSamples(sampleBuffer, nSamples);

        // Read ready samples from SoundTouch processor & write them output file.
        // NOTES:
        // - 'receiveSamples' doesn't necessarily return any samples at all
        //   during some rounds!
        // - On the other hand, during some round 'receiveSamples' may have more
        //   ready samples than would fit into 'sampleBuffer', and for this reason 
        //   the 'receiveSamples' call is iterated for as many times as it
        //   outputs samples.
        do 
        {
            nSamples = pSoundTouch->receiveSamples(sampleBuffer, buffSizeSamples);
            outFile->write(sampleBuffer, nSamples * nChannels);
        } while (nSamples != 0);
    }

    // Now the input file is processed, yet 'flush' few last samples that are
    // hiding in the SoundTouch's internal processing pipeline.
    pSoundTouch->flush();
    do 
    {
        nSamples = pSoundTouch->receiveSamples(sampleBuffer, buffSizeSamples);
        outFile->write(sampleBuffer, nSamples * nChannels);
    } while (nSamples != 0);
}