annotate projects/level_meter/render.cpp @ 151:e9c9404e3d1f ClockSync

Pff partially working. No PID. When setting the audio clock on the bbb to 44098 the master and slave clock keep diverging instead of converging ...
author Giulio Moro <giuliomoro@yahoo.it>
date Tue, 22 Sep 2015 04:10:07 +0100
parents 3a5823f7a11f
children 8d80eda512cd
rev   line source
andrewm@88 1 /*
andrewm@88 2 * render.cpp
andrewm@88 3 *
andrewm@88 4 * Created on: Oct 24, 2014
andrewm@88 5 * Author: parallels
andrewm@88 6 */
andrewm@88 7
andrewm@88 8
andrewm@88 9 #include <BeagleRT.h>
andrewm@88 10 #include <Utilities.h>
andrewm@88 11 #include <cmath>
andrewm@88 12
andrewm@88 13 #define NUMBER_OF_SEGMENTS 10
andrewm@88 14
andrewm@88 15 // Two levels of audio: one follows current value, the other holds
andrewm@88 16 // peaks for longer
andrewm@88 17 float gAudioLocalLevel = 0, gAudioPeakLevel = 0;
andrewm@88 18
andrewm@88 19 // Decay rates for detecting levels
andrewm@88 20 float gLocalDecayRate = 0.99, gPeakDecayRate = 0.999;
andrewm@88 21
andrewm@88 22 // Thresholds for LEDs: set in setup()
andrewm@88 23 float gThresholds[NUMBER_OF_SEGMENTS + 1];
andrewm@88 24
andrewm@88 25 // High-pass filter on the input
andrewm@88 26 float gLastX[2] = {0};
andrewm@88 27 float gLastY[2] = {0};
andrewm@88 28
andrewm@88 29 // These coefficients make a high-pass filter at 5Hz for 44.1kHz sample rate
andrewm@88 30 double gB0 = 0.99949640;
andrewm@88 31 double gB1 = -1.99899280;
andrewm@88 32 double gB2 = gB0;
andrewm@88 33 double gA1 = -1.99899254;
andrewm@88 34 double gA2 = 0.99899305;
andrewm@88 35
andrewm@88 36 // setup() is called once before the audio rendering starts.
andrewm@88 37 // Use it to perform any initialisation and allocation which is dependent
andrewm@88 38 // on the period size or sample rate.
andrewm@88 39 //
andrewm@88 40 // userData holds an opaque pointer to a data structure that was passed
andrewm@88 41 // in from the call to initAudio().
andrewm@88 42 //
andrewm@88 43 // Return true on success; returning false halts the program.
andrewm@88 44
andrewm@88 45 bool setup(BeagleRTContext *context, void *userData)
andrewm@88 46 {
andrewm@88 47 // This project makes the assumption that the audio and digital
andrewm@88 48 // sample rates are the same. But check it to be sure!
andrewm@88 49 if(context->audioFrames != context->digitalFrames) {
andrewm@88 50 rt_printf("Error: this project needs the audio and digital sample rates to be the same.\n");
andrewm@88 51 return false;
andrewm@88 52 }
andrewm@88 53
andrewm@88 54 // Initialise threshold levels in -3dB steps. One extra for efficiency in render()
andrewm@88 55 // Level = 10^(dB/20)
andrewm@88 56 for(int i = 0; i < NUMBER_OF_SEGMENTS + 1; i++) {
andrewm@88 57 gThresholds[i] = powf(10.0f, (-1.0 * (NUMBER_OF_SEGMENTS - i)) * .05);
andrewm@88 58 }
andrewm@88 59
andrewm@88 60 for(int i = 0; i < NUMBER_OF_SEGMENTS; i++)
andrewm@88 61 pinModeFrame(context, 0, i, OUTPUT);
andrewm@88 62
andrewm@88 63 return true;
andrewm@88 64 }
andrewm@88 65
andrewm@88 66 // render() is called regularly at the highest priority by the audio engine.
andrewm@88 67 // Input and output are given from the audio hardware and the other
andrewm@88 68 // ADCs and DACs (if available). If only audio is available, numMatrixFrames
andrewm@88 69 // will be 0.
andrewm@88 70
andrewm@88 71 void render(BeagleRTContext *context, void *userData)
andrewm@88 72 {
andrewm@88 73 for(unsigned int n = 0; n < context->audioFrames; n++) {
andrewm@88 74 // Get average of audio input channels
andrewm@88 75 float sample = 0;
andrewm@88 76 for(unsigned int ch = 0; ch < context->audioChannels; ch++) {
andrewm@88 77 context->audioOut[n * context->audioChannels + ch] =
andrewm@88 78 context->audioIn[n * context->audioChannels + ch];
andrewm@88 79 sample += context->audioIn[n * context->audioChannels + ch];
andrewm@88 80 }
andrewm@88 81
andrewm@88 82 // Do DC-blocking on the sum
andrewm@88 83 float out = gB0 * sample + gB1 * gLastX[0] + gB2 * gLastX[1]
andrewm@88 84 - gA1 * gLastY[0] - gA2 * gLastY[1];
andrewm@88 85
andrewm@88 86 gLastX[1] = gLastX[0];
andrewm@88 87 gLastX[0] = sample;
andrewm@88 88 gLastY[1] = gLastY[0];
andrewm@88 89 gLastY[0] = out;
andrewm@88 90
andrewm@88 91 out = fabsf(out / (float)context->audioChannels);
andrewm@88 92
andrewm@88 93 // Do peak detection: fast-responding local level
andrewm@88 94 if(out > gAudioLocalLevel)
andrewm@88 95 gAudioLocalLevel = out;
andrewm@88 96 else
andrewm@88 97 gAudioLocalLevel *= gLocalDecayRate;
andrewm@88 98
andrewm@88 99 // Do peak detection: slow-responding peak level
andrewm@88 100 if(out > gAudioPeakLevel)
andrewm@88 101 gAudioPeakLevel = out;
andrewm@88 102 else {
andrewm@88 103 // Make peak decay slowly by only multiplying
andrewm@88 104 // every few samples
andrewm@88 105 if(((context->audioSampleCount + n) & 31) == 0)
andrewm@88 106 gAudioPeakLevel *= gPeakDecayRate;
andrewm@88 107 }
andrewm@88 108 // LED bargraph on digital outputs 0-9
andrewm@88 109 for(int led = 0; led < NUMBER_OF_SEGMENTS; led++) {
andrewm@88 110 // All LEDs up to the local level light up. The LED
andrewm@88 111 // for the peak level also remains lit.
andrewm@88 112 int state = LOW;
andrewm@88 113
andrewm@88 114 if(gAudioLocalLevel > gThresholds[led])
andrewm@88 115 state = HIGH;
andrewm@88 116 else if(gAudioPeakLevel > gThresholds[led] && gAudioPeakLevel <= gThresholds[led + 1])
andrewm@88 117 state = HIGH;
andrewm@88 118
andrewm@88 119 // Write LED
andrewm@88 120 digitalWriteFrameOnce(context, n, led, state);
andrewm@88 121 }
andrewm@88 122 }
andrewm@88 123 }
andrewm@88 124
andrewm@88 125 // cleanup() is called once at the end, after the audio has stopped.
andrewm@88 126 // Release any resources that were allocated in setup().
andrewm@88 127
andrewm@88 128 void cleanup(BeagleRTContext *context, void *userData)
andrewm@88 129 {
andrewm@88 130
andrewm@88 131 }