annotate projects/measure_noisefloor/render.cpp @ 91:241d4d5df929

Double buffered the noise floor project; works without glitches now

/*
 * render.cpp
 *
 *  Created on: Oct 24, 2014
 *      Author: parallels
 */


#include <BeagleRT.h>
#include <Utilities.h>
#include <cmath>

int gBufferSize = 8192;

// Double buffers to hold samples for noise analysis
float *gReadBuffers[10], *gWriteBuffers[10];
float *gBuffers0[10], *gBuffers1[10];

int gWriteBufferPointers[10], gReadBufferPointers[10];

// Task to analyse and print results which would otherwise be too slow for render()
AuxiliaryTask gAnalysisTask;

void analyseResults();

// setup() 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 setup(BeagleRTContext *context, void *userData)
{	
	// Clear the filter data structures
	for(int i = 0; i < 10; i++) {
		gReadBufferPointers[i] = gWriteBufferPointers[i] = 0;
		gBuffers0[i] = new float[gBufferSize];
		gBuffers1[i] = new float[gBufferSize];		
		gWriteBuffers[i] = gBuffers0[i];
		gReadBuffers[i] = gBuffers1[i];
		if(gBuffers0[i] == 0 || gBuffers1[i] == 0) {
			rt_printf("Error allocating buffer %d\n", i);
			return false;
		}
	}
	
	gAnalysisTask = BeagleRT_createAuxiliaryTask(analyseResults, 50, "beaglert-analyse-results");

	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(BeagleRTContext *context, void *userData)
{
	bool bufferIsFull = false;	// Whether at least one buffer has filled
	
	for(unsigned int n = 0; n < context->audioFrames; n++) {
		// Store audio inputs in buffer
		for(unsigned int ch = 0; ch < context->audioChannels; ch++) {
			if(gWriteBufferPointers[ch] < gBufferSize) {
				gWriteBuffers[ch][gWriteBufferPointers[ch]] = 
					context->audioIn[n * context->audioChannels + ch];
				gWriteBufferPointers[ch]++;
				if(gWriteBufferPointers[ch] >= gBufferSize)
					bufferIsFull = true;
			}
		}
	}
	
	if(context->analogChannels != 0) {
		for(unsigned int n = 0; n < context->analogFrames; n++) {
			// Store analog inputs in buffer, starting at channel 2
			for(unsigned int ch = 0; ch < context->analogChannels; ch++) {
				if(gWriteBufferPointers[ch + 2] < gBufferSize) {
					gWriteBuffers[ch + 2][gWriteBufferPointers[ch + 2]] = 
						context->analogIn[n * context->analogChannels + ch];
					gWriteBufferPointers[ch + 2]++;
					if(gWriteBufferPointers[ch + 2] >= gBufferSize)
						bufferIsFull = true;
				}
				
				// Set all analog outputs to halfway point so they can be more
				// easily measured for noise
				context->analogOut[n * context->analogChannels + ch] = 0.5;
			}
		}	
	}
	

	if(bufferIsFull) {
		// Swap buffers and reset write pointers
		for(int ch = 0; ch < 10; ch++) {
			gReadBufferPointers[ch] = gWriteBufferPointers[ch];
			gWriteBufferPointers[ch] = 0;
			
			if(gReadBuffers[ch] == gBuffers0[ch]) {
				gReadBuffers[ch] = gBuffers1[ch];
				gWriteBuffers[ch] = gBuffers0[ch];
			}
			else {
				gReadBuffers[ch] = gBuffers0[ch];
				gWriteBuffers[ch] = gBuffers1[ch];				
			}
		}
		
		BeagleRT_scheduleAuxiliaryTask(gAnalysisTask);
	}
}

void analyseResults()
{
	rt_printf("\e[1;1H\e[2J");	// Command to clear the screen

	// Print the analysis results. channels 0-1 are audio, channels 2-9 are analog
	for(int ch = 0; ch < 10; ch++) {
		// Skip unused channels
		if(gReadBufferPointers[ch] == 0)
			continue;
		
		float mean = 0;
		for(int n = 0; n < gReadBufferPointers[ch]; n++) {
			mean += gReadBuffers[ch][n];
		}
		mean /= (float)gReadBufferPointers[ch];
		
		float rms = 0;
		for(int n = 0; n < gReadBufferPointers[ch]; n++) {
			rms += (gReadBuffers[ch][n] - mean) * (gReadBuffers[ch][n] - mean);
		}				
		rms = sqrtf(rms / (float)gReadBufferPointers[ch]);
		
		if(ch == 0)
			rt_printf("Audio In L:  ");
		else if(ch == 1)
			rt_printf("Audio In R:  ");
		else
			rt_printf("Analog In %d: ", ch - 2);
		
		rt_printf("Noise %6.1fdB    DC offset %6.4f (%6.1fdB)    window size: %d\n", 
					20.0f * log10f(rms),
					mean, 
					20.0f * log10f(fabsf(mean)),
					gReadBufferPointers[ch]);
	}
}

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

void cleanup(BeagleRTContext *context, void *userData)
{
	for(int i = 0; i < 10; i++) {
		delete gBuffers0[i];
		delete gBuffers1[i];
	}
}