Resample a folder of testsignals

ResamplerTest.cpp

/*
  ==============================================================================

    Resample the test signals in the folder

  ==============================================================================
*/

#include <juce_core/juce_core.h>
#include <juce_audio_formats/juce_audio_formats.h>
#include <juce_dsp/juce_dsp.h>


int main (int, char**)
{
    constexpr auto sampleRate = 44100.0;
    using ResamplerType=juce::ResamplingAudioSource;
    
    auto folder = juce::File::getSpecialLocation (juce::File::userDesktopDirectory).getChildFile("TestSignals");
    auto output = folder.getChildFile("output");
    output.createDirectory();
    
    juce::WavAudioFormat format;
    
    for (auto file : folder.findChildFiles(juce::File::findFiles, false))
    {
        if (!file.hasFileExtension(".wav"))
            continue;
        
        auto input  = file.createInputStream();
        auto reader = format.createReaderFor(input.release(), true);
        
        if (!reader)
        {
            DBG ("Creating reader failed: " << file.getFullPathName());
            continue;
        }
        
        const auto sourceSampleRate = reader->sampleRate;
        const auto numSourceSamples = reader->lengthInSamples;
        const auto numChannels = reader->numChannels;
        const auto blockSize = 512;
        
        auto source = std::make_unique<juce::AudioFormatReaderSource>(reader, true);
        
        auto outputFile = output.getChildFile(file.getFileName());
        auto outputStream = outputFile.createOutputStream();
        outputStream->setPosition(0);
        outputStream->truncate();
        
        auto writer = std::unique_ptr<juce::AudioFormatWriter>(format.createWriterFor(outputStream.release(), sampleRate, reader->numChannels, reader->bitsPerSample, {}, 0));
        
        if (!writer)
        {
            DBG ("Creating writer failed: " << outputFile.getFullPathName());
            continue;
        }
        
        auto resampler = std::make_unique<ResamplerType>(source.release(), true, numChannels);
        
        juce::AudioBuffer<float> buffer (numChannels, blockSize);
        juce::AudioSourceChannelInfo info (buffer);
        
        const auto ratio = sourceSampleRate / sampleRate;
        const auto numTargetSamples = numSourceSamples / ratio;
        
        resampler->setResamplingRatio(ratio);
        resampler->prepareToPlay(blockSize, sampleRate);
        
        juce::int64 pos = 0;
        while (pos < numTargetSamples)
        {
            resampler->getNextAudioBlock(info);
            writer->writeFromAudioSampleBuffer(buffer, 0, blockSize);
            pos += blockSize;
        }
    }
    
    return 0;
}