Resampling while streaming

[marvinh]

https://gist.github.com/marvinh/f0f36dd176566f99ba2a252dbfe7005e

I have a gist here if you want to include in examples with juce. super thread safe I think I have no issues .

[marvinh]

this is much better not streaming but loving this library
edited: for caching sample position
of course needs a little work correct bit depth based on the info and interleaving properly

class SampleReader {
public:
    SampleReader(const std::string& filename){
        stream = audio::ifstream(filename);
        
        num_frames = stream.info().num_frames();
        num_samples = stream.info().num_samples();
        num_channels = stream.info().num_channels();
        sample_rate = stream.info().sample_rate();
        
        fm = boost::interprocess::file_mapping(filename.c_str(), boost::interprocess::read_only);
        mr = boost::interprocess::mapped_region(fm, boost::interprocess::read_only);
        mr.advise( boost::interprocess::mapped_region::advice_willneed);
        mr.advise( boost::interprocess::mapped_region::advice_sequential);
        mm = static_cast<char*>(mr.get_address())+44;
        rt_fmt = pcm::make_format(pcm::signed_integer,pcm::_24bit, pcm::little_endian);
        rt_it = pcm::make_iterator<float,char*>(mm, rt_fmt);
        data.resize(96,0);
    }
    
    size_t lastPosition = 0;
    float readSample(size_t position, int cache)  {
        if(position < 0 || position > num_frames) {
            return 0.0f;
        }
        if(cache == 0 && position != lastPosition) {
            pcm::iterator<float, char*> m = (rt_it+position);
            for(int i = 0; i < 24; i++) {
                data[i] = *m++;
            }
            lastPosition = position;
            return data[0];
        }else{
            return data[cache];
        }
        
    }
    
    std::vector<float> data;
    boost::interprocess::file_mapping fm;
    boost::interprocess::mapped_region mr;
    pcm::format rt_fmt;
    pcm::iterator<float, char*> rt_it;
    char * mm;
    audio::ifstream stream;
    size_t num_frames;
    size_t num_samples;
    size_t num_channels;
    double sample_rate;
};