victor@1: /*
robert@372:  ____  _____ _        _    
robert@372: | __ )| ____| |      / \   
robert@372: |  _ \|  _| | |     / _ \  
robert@372: | |_) | |___| |___ / ___ \ 
robert@372: |____/|_____|_____/_/   \_\.io
robert@372: 
victor@1:  */
victor@1: 
robert@372: /*
robert@372:  *
robert@372:  * Andrew McPherson and Victor Zappi
robert@372:  * Queen Mary, University of London
robert@372:  */
robert@372: 
robert@372: /**
robert@372: \example 4_audio_samples
robert@372: 
robert@372: Playback WAV files
robert@372: ------------------
robert@372: 
robert@372: This sketch shows how to playback audio samples from a buffer.
robert@372: 
robert@372: An audio file is loaded into a buffer `SampleData` as `gSampleData`. This is 
robert@372: accessed with a read pointer that is incremented at audio rate within the render 
robert@372: function: `out += gSampleData.samples[gReadPtr++]`.
robert@372: 
robert@372: Note that the read pointer is stopped from incrementing past the length of the 
robert@372: `gSampleData`. This is achieved by comparing the read pointer value against the 
robert@372: sample length which we can access as follows: `gSampleData.sampleLen`.
robert@372: 
robert@372: The sample is triggered by keyboard input: (a) starts sample playback, (s) 
robert@372: stops sample playback. The triggering is treated as a lower priority task than 
robert@372: the audio. You can see this at the bottom of the render function: 
robert@372: `Bela_scheduleAuxiliaryTask(gTriggerSamplesTask)`;
robert@372: */
victor@1: 
giuliomoro@301: #include <Bela.h>
victor@1: #include <cmath>
victor@1: #include "SampleData.h"
victor@1: 
victor@1: SampleData gSampleData;	// User defined structure to get complex data from main
victor@1: int gReadPtr;			// Position of last read sample from file
victor@1: 
victor@1: // Task for handling the update of the frequencies using the matrix
victor@1: AuxiliaryTask gTriggerSamplesTask;
victor@1: 
victor@1: bool initialise_trigger();
victor@1: void trigger_samples();
victor@1: 
andrewm@56: // setup() is called once before the audio rendering starts.
victor@1: // Use it to perform any initialisation and allocation which is dependent
victor@1: // on the period size or sample rate.
victor@1: //
victor@1: // userData holds an opaque pointer to a data structure that was passed
victor@1: // in from the call to initAudio().
victor@1: //
victor@1: // Return true on success; returning false halts the program.
victor@1: 
giuliomoro@301: bool setup(BelaContext *context, void *userData)
victor@1: {
victor@1: 
victor@1: 	// Retrieve a parameter passed in from the initAudio() call
victor@1: 	gSampleData = *(SampleData *)userData;
victor@1: 
victor@1: 	gReadPtr = -1;
victor@1: 
victor@1: 	// Initialise auxiliary tasks
victor@1: 	if(!initialise_trigger())
victor@1: 		return false;
victor@1: 
victor@1: 	return true;
victor@1: }
victor@1: 
victor@1: // render() is called regularly at the highest priority by the audio engine.
victor@1: // Input and output are given from the audio hardware and the other
victor@1: // ADCs and DACs (if available). If only audio is available, numMatrixFrames
victor@1: // will be 0.
victor@1: 
giuliomoro@301: void render(BelaContext *context, void *userData)
victor@1: {
andrewm@56: 	for(unsigned int n = 0; n < context->audioFrames; n++) {
victor@1: 		float out = 0;
victor@1: 
victor@1: 		// If triggered...
victor@1: 		if(gReadPtr != -1)
victor@1: 			out += gSampleData.samples[gReadPtr++];	// ...read each sample...
victor@1: 
victor@1: 		if(gReadPtr >= gSampleData.sampleLen)
victor@1: 			gReadPtr = -1;
victor@1: 
andrewm@56: 		for(unsigned int channel = 0; channel < context->audioChannels; channel++)
andrewm@52: 			context->audioOut[n * context->audioChannels + channel] = out;	// ...and put it in both left and right channel
victor@1: 	}
victor@1: 
victor@1: 	// Request that the lower-priority task run at next opportunity
giuliomoro@301: 	Bela_scheduleAuxiliaryTask(gTriggerSamplesTask);
victor@1: }
victor@1: 
victor@1: // Initialise the auxiliary task
victor@1: // and print info
victor@1: 
victor@1: bool initialise_trigger()
victor@1: {
andrewm@303: 	if((gTriggerSamplesTask = Bela_createAuxiliaryTask(&trigger_samples, 50, "bela-trigger-samples")) == 0)
victor@1: 		return false;
victor@1: 
victor@1: 	rt_printf("Press 'a' to trigger sample, 's' to stop\n");
victor@1: 	rt_printf("Press 'q' to quit\n");
victor@1: 
victor@1: 	return true;
victor@1: }
victor@1: 
victor@1: // This is a lower-priority call to periodically read keyboard input
victor@1: // and trigger samples. By placing it at a lower priority,
victor@1: // it has minimal effect on the audio performance but it will take longer to
victor@1: // complete if the system is under heavy audio load.
victor@1: 
victor@1: void trigger_samples()
victor@1: {
victor@1: 	// This is not a real-time task!
victor@1: 	// Cos getchar is a system call, not handled by Xenomai.
victor@1: 	// This task will be automatically down graded.
victor@1: 
victor@1: 	char keyStroke = '.';
victor@1: 
victor@1: 	keyStroke =	getchar();
victor@1: 	while(getchar()!='\n'); // to read the first stroke
victor@1: 
victor@1: 	switch (keyStroke)
victor@1: 	{
victor@1: 		case 'a':
victor@1: 			gReadPtr = 0;
victor@1: 			break;
victor@1: 		case 's':
victor@1: 			gReadPtr = -1;
victor@1: 			break;
victor@1: 		case 'q':
victor@1: 			gShouldStop = true;
victor@1: 			break;
victor@1: 		default:
victor@1: 			break;
victor@1: 	}
victor@1: }
victor@1: 
victor@1: 
victor@1: 
andrewm@56: // cleanup() is called once at the end, after the audio has stopped.
andrewm@56: // Release any resources that were allocated in setup().
victor@1: 
giuliomoro@301: void cleanup(BelaContext *context, void *userData)
victor@1: {
victor@1: 	delete[] gSampleData.samples;
victor@1: }