annotate projects/samples/render.cpp @ 1:24fc8026ae8e

_new sample playback example

/*
 * render.cpp
 *
 *  Created on: Oct 24, 2014
 *      Author: Andrew McPherson and Victor Zappi
 */


#include "../../include/render.h"
#include "../../include/RTAudio.h"	// to schedule lower prio parallel process
#include <rtdk.h>
#include <cmath>
#include <stdio.h>
#include "SampleData.h"

SampleData gSampleData;	// User defined structure to get complex data from main
int gReadPtr;			// Position of last read sample from file
int gNumChannels;

// Task for handling the update of the frequencies using the matrix
AuxiliaryTask gTriggerSamplesTask;

bool initialise_trigger();
void trigger_samples();

// initialise_render() is called once before the audio rendering starts.
// Use it to perform any initialisation and allocation which is dependent
// on the period size or sample rate.
//
// userData holds an opaque pointer to a data structure that was passed
// in from the call to initAudio().
//
// Return true on success; returning false halts the program.

bool initialise_render(int numChannels, int numMatrixFramesPerPeriod,
					   int numAudioFramesPerPeriod, float matrixSampleRate,
					   float audioSampleRate, void *userData)
{

	// Retrieve a parameter passed in from the initAudio() call
	gSampleData = *(SampleData *)userData;

	gReadPtr = -1;
	gNumChannels = numChannels;

	// Initialise auxiliary tasks
	if(!initialise_trigger())
		return false;

	return true;
}

// render() is called regularly at the highest priority by the audio engine.
// Input and output are given from the audio hardware and the other
// ADCs and DACs (if available). If only audio is available, numMatrixFrames
// will be 0.

void render(int numMatrixFrames, int numAudioFrames, float *audioIn, float *audioOut,
			uint16_t *matrixIn, uint16_t *matrixOut)
{
	for(int n = 0; n < numAudioFrames; n++) {
		float out = 0;

		// If triggered...
		if(gReadPtr != -1)
			out += gSampleData.samples[gReadPtr++];	// ...read each sample...

		if(gReadPtr >= gSampleData.sampleLen)
			gReadPtr = -1;

		for(int channel = 0; channel < gNumChannels; channel++)
			audioOut[n * gNumChannels + channel] = out;	// ...and put it in both left and right channel
	}

	// Request that the lower-priority task run at next opportunity
	scheduleAuxiliaryTask(gTriggerSamplesTask);
}

// Initialise the auxiliary task
// and print info

bool initialise_trigger()
{
	if((gTriggerSamplesTask = createAuxiliaryTaskLoop(&trigger_samples, 50, "beaglert-trigger-samples")) == 0)
		return false;

	rt_printf("Press 'a' to trigger sample, 's' to stop\n");
	rt_printf("Press 'q' to quit\n");

	return true;
}

// This is a lower-priority call to periodically read keyboard input
// and trigger samples. By placing it at a lower priority,
// it has minimal effect on the audio performance but it will take longer to
// complete if the system is under heavy audio load.

void trigger_samples()
{
	// This is not a real-time task!
	// Cos getchar is a system call, not handled by Xenomai.
	// This task will be automatically down graded.

	char keyStroke = '.';

	keyStroke =	getchar();
	while(getchar()!='\n'); // to read the first stroke

	switch (keyStroke)
	{
		case 'a':
			gReadPtr = 0;
			break;
		case 's':
			gReadPtr = -1;
			break;
		case 'q':
			gShouldStop = true;
			break;
		default:
			break;
	}
}



// cleanup_render() is called once at the end, after the audio has stopped.
// Release any resources that were allocated in initialise_render().

void cleanup_render()
{
	delete[] gSampleData.samples;
}