void SourceFile::seek( size_t readPositionFrames )
{
if( readPositionFrames >= mNumFrames )
return;
// adjust read pos for samplerate conversion so that it is relative to file num frames
size_t fileReadPos = readPositionFrames;
if( getSampleRate() != getSampleRateNative() )
fileReadPos *= size_t( (float)mFileNumFrames / (float)mNumFrames );
performSeek( fileReadPos );
mReadPos = readPositionFrames;
}
void SourceFile::setupSampleRateConversion()
{
size_t nativeSampleRate = getSampleRateNative();
size_t outputSampleRate = getSampleRate();
if( ! outputSampleRate ) {
outputSampleRate = nativeSampleRate;
setSampleRate( nativeSampleRate );
}
else if( outputSampleRate != nativeSampleRate ) {
mNumFrames = (size_t)std::ceil( (float)mFileNumFrames * (float)outputSampleRate / (float)nativeSampleRate );
if( ! supportsConversion() ) {
size_t numChannels = getNumChannels();
mConverter = audio::dsp::Converter::create( nativeSampleRate, outputSampleRate, numChannels, numChannels, getMaxFramesPerRead() );
mConverterReadBuffer.setSize( getMaxFramesPerRead(), numChannels );
}
}
else {
mNumFrames = mFileNumFrames;
mConverter.reset();
}
}
size_t SourceFile::read( Buffer *buffer )
{
CI_ASSERT( buffer->getNumChannels() == getNumChannels() );
CI_ASSERT( mReadPos < mNumFrames );
size_t numRead;
if( mConverter ) {
size_t sourceBufFrames = size_t( buffer->getNumFrames() * (float)getSampleRateNative() / (float)getSampleRate() );
size_t numFramesNeeded = std::min( mFileNumFrames - mReadPos, std::min( getMaxFramesPerRead(), sourceBufFrames ) );
mConverterReadBuffer.setNumFrames( numFramesNeeded );
performRead( &mConverterReadBuffer, 0, numFramesNeeded );
pair<size_t, size_t> count = mConverter->convert( &mConverterReadBuffer, buffer );
numRead = count.second;
}
else {
size_t numFramesNeeded = std::min( mNumFrames - mReadPos, std::min( getMaxFramesPerRead(), buffer->getNumFrames() ) );
numRead = performRead( buffer, 0, numFramesNeeded );
}
mReadPos += numRead;
return numRead;
}
