Audio/sample-loader/render.cpp

Simple Sample Loader

This example loads a specified range of samples from a file into a buffer using a helper function provided in libraries/AudioFile/AudioFile.h. This should be used when working with small wav files. See sampleStreamer and sampleStreamerMulti for more elaborate ways of loading and playing back larger files.

/*
 ____  _____ _        _
| __ )| ____| |      / \
|  _ \|  _| | |     / _ \
| |_) | |___| |___ / ___ \
|____/|_____|_____/_/   \_\
http://bela.io
*/
 
#include <Bela.h>
#include <libraries/AudioFile/AudioFile.h>
#include <vector>
 
std::string gFilename = "waves.wav";
int gStartFrame = 44100;
int gEndFrame = 88200;
 
std::vector<std::vector<float> > gSampleData;
 
unsigned int gReadPtr; // Position of last read sample from file
 
bool setup(BelaContext *context, void *userData)
{
        gSampleData = AudioFileUtilities::load(gFilename, gEndFrame - gStartFrame, gStartFrame);
        return true;
}
 
void render(BelaContext *context, void *userData)
{
    for(unsigned int n = 0; n < context->audioFrames; n++) {
 
        // Increment read pointer and reset to 0 when end of file is reached
        if(++gReadPtr > gSampleData[0].size())
            gReadPtr = 0;
 
        for(unsigned int channel = 0; channel < context->audioOutChannels; channel++) {
            // Wrap channel index in case there are more audio output channels than the file contains
                float out = gSampleData[channel%gSampleData.size()][gReadPtr];
                audioWrite(context, n, channel, out);
        }
    }
}
 
 
void cleanup(BelaContext *context, void *userData)
{
}