diff projects/measure_noisefloor/render.cpp @ 89:d41631e0fe0e

Added noise floor measurement project; also added option to run script to run without screen

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/projects/measure_noisefloor/render.cpp	Sun Jul 19 16:15:28 2015 +0100
@@ -0,0 +1,155 @@
+/*
+ * render.cpp
+ *
+ *  Created on: Oct 24, 2014
+ *      Author: parallels
+ */
+
+
+#include <BeagleRT.h>
+#include <Utilities.h>
+#include <cmath>
+
+int gBufferSize = 8192;
+
+// Buffers to hold samples for noise analysis
+float* gBuffers[10];
+int gBufferPointers[10];
+
+// Outputs to display
+float gDCLevels[10];
+float gNoiseLevels[10];
+float gNumSamplesAnalysed[10];
+
+// Task to print results which would otherwise be too slow for render()
+AuxiliaryTask gPrintTask;
+
+void printResults();
+
+// 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++) {
+		gBufferPointers[i] = 0;
+		gBuffers[i] = new float[gBufferSize];
+		if(gBuffers[i] == 0) {
+			rt_printf("Error allocating buffer %d\n", i);
+			return false;
+		}
+	}
+	
+	gPrintTask = BeagleRT_createAuxiliaryTask(printResults, 50, "beaglert-print-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(gBufferPointers[ch] < gBufferSize) {
+				gBuffers[ch][gBufferPointers[ch]] = 
+					context->audioIn[n * context->audioChannels + ch];
+				gBufferPointers[ch]++;
+				if(gBufferPointers[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(gBufferPointers[ch + 2] < gBufferSize) {
+					gBuffers[ch + 2][gBufferPointers[ch + 2]] = 
+						context->analogIn[n * context->analogChannels + ch];
+					gBufferPointers[ch + 2]++;
+					if(gBufferPointers[ch + 2] >= gBufferSize)
+						bufferIsFull = true;
+				}
+			}
+		}	
+	}
+
+	if(bufferIsFull) {
+		// Analyse all active channels at once
+		for(int ch = 0; ch < 10; ch++) {
+			// gBufferPointers[ch] tells us how many samples were stored in the buffer
+			gNumSamplesAnalysed[ch] = gBufferPointers[ch];
+			
+			if(gBufferPointers[ch] != 0) {
+				float mean = 0;
+				for(int n = 0; n < gBufferPointers[ch]; n++) {
+					mean += gBuffers[ch][n];
+				}
+				mean /= (float)gBufferPointers[ch];
+				
+				float rms = 0;
+				for(int n = 0; n < gBufferPointers[ch]; n++) {
+					rms += (gBuffers[ch][n] - mean) * (gBuffers[ch][n] - mean);
+				}				
+				rms = sqrtf(rms / (float)gBufferPointers[ch]);
+				
+				gDCLevels[ch] = mean;
+				gNoiseLevels[ch] = rms;
+			}
+			
+			// Reset pointer to 0 for next time
+			gBufferPointers[ch] = 0;
+		}
+		
+		BeagleRT_scheduleAuxiliaryTask(gPrintTask);
+	}
+}
+
+void printResults()
+{
+	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++) {
+		int samples = gNumSamplesAnalysed[ch];
+		if(samples == 0)
+			continue;
+		
+		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(gNoiseLevels[ch]),
+					gDCLevels[ch], 
+					20.0f * log10f(fabsf(gDCLevels[ch])),
+					samples);
+	}
+}
+
+// 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 gBuffers[i];
+}