First commit

AudioTuner.cpp

+/* Audio Library Guitar Tuner
+ * Copyright (c) 2015, Colin Duffy
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice, development funding notice, and this permission
+ * notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "AudioTuner.h"
+
+#define HALF_BUFFER         NUM_SAMPLES / 2
+#define QUARTER_BUFFER      NUM_SAMPLES / 4
+#define EIGTH_BUFFER        NUM_SAMPLES / 8
+#define SIXTEENTH_BUFFER    NUM_SAMPLES / 16
+#define SAMPLE_RATE AUDIO_SAMPLE_RATE_EXACT / SAMPLE_SKIP
+
+#define LOOP1(a)  a
+#define LOOP2(a)  a LOOP1(a)
+#define LOOP3(a)  a LOOP2(a)
+#define LOOP8(a)  a LOOP3(a) a LOOP3(a)
+#define UNROLL(n,a) LOOP##n(a)
+
+#define WINDOW SAMPLE_SKIP - 1
+
+/**
+ *  audio update function.
+ */
+void AudioTuner::update( void ) {
+    audio_block_t *block;
+    const int16_t *p, *end;
+    block = receiveReadOnly( );
+    if ( !block ) return;
+    if ( !enabled ) {
+        release( block );
+        return;
+    }
+    
+    p = block->data;
+    end = p + AUDIO_BLOCK_SAMPLES;
+    
+    uint16_t *dst;
+    if ( next_buffer ) dst = ( uint16_t * )buffer;
+    else dst = ( uint16_t * )buffer + NUM_SAMPLES;
+    
+    uint8_t get_sample = 0;
+    uint16_t count = block_count;
+    do {
+        if ( get_sample++ >= WINDOW ) {
+            *( dst+count++ ) = *( uint16_t * )p;
+            get_sample = 0;
+        }
+    } while ( p++ < end );
+    release( block );
+
+    if ( count >= NUM_SAMPLES ) {
+        digitalWriteFast(2, !digitalReadFast(2));
+        next_buffer = !next_buffer;
+        process_buffer = true;
+        tau_global = 1;
+        yin_idx = 1;
+        running_sum = 0;
+        count = 0;
+    }
+    block_count = count;
+    
+    if ( process_buffer ) {
+        digitalWriteFast(0, HIGH);
+        uint16_t tau;
+        uint16_t  next;
+        next = next_buffer;
+        tau = tau_global;
+        do {
+            int64_t sum  = 0;
+            const int16_t *end, *buf;
+            if ( next ) buf = buffer + NUM_SAMPLES;
+            else buf = buffer;
+            end = buf + HALF_BUFFER;
+            do {
+                int16_t current, lag, delta;
+                UNROLL( 8,
+                       lag = *( buf + tau );
+                       current = *buf++;
+                       delta = current - lag;
+                       sum += delta*delta;
+                       );
+            } while ( buf < end );
+            
+            running_sum += sum;
+            yin_buffer[yin_idx] = sum*tau;
+            rs_buffer[yin_idx] = running_sum;
+            yin_idx = ( ++yin_idx >= 5 ) ? 0 : yin_idx;
+            tau = estimate( yin_buffer, rs_buffer, yin_idx, tau );
+            if ( tau == 0 ) {
+                process_buffer = false;
+                new_output = true;
+                digitalWriteFast(0, LOW);
+                return;
+            }
+            else if ( tau >= HALF_BUFFER ) {
+                process_buffer = false;
+                new_output = false;
+                digitalWriteFast(0, LOW);
+                return;
+            }
+        } while ( tau <= ( tau_global + 31 ) );
+        tau_global = tau;
+        digitalWriteFast(0, LOW);
+    }
+}
+
+/**
+ *  process data in from Audio Library interrupt
+ */
+uint16_t AudioTuner::estimate( int64_t *yin, int64_t *rs, uint16_t head, uint16_t tau ) {
+    const int64_t *p = ( int64_t * )yin;
+    const int64_t *r = ( int64_t * )rs;
+    uint16_t period = 0, _tau, _head;
+    _tau = tau;
+    _head = head;
+    
+    if ( _tau > 4 ) {
+        uint16_t idx0, idx1, idx2;
+        idx0 = _head;
+        idx1 = _head + 1;
+        idx1 = ( idx1 >= 5 ) ? 0 : idx1;
+        idx2 = head + 2;
+        idx2 = ( idx2 >= 5 ) ? 0 : idx2;
+        
+        float s0, s1, s2;
+        s0 = ( ( float )*( p+idx0 ) / r[idx0] );
+        s1 = ( ( float )*( p+idx1 ) / r[idx1] );
+        s2 = ( ( float )*( p+idx2 ) / r[idx2] );
+        
+        if ( s1 < threshold && s1 < s2 ) {
+            period = _tau - 3;
+            periodicity = 1 - s1;
+            data = period + 0.5f * ( s0 - s2 ) / ( s0 - 2.0f * s1 + s2 );
+            return 0;
+        }
+        
+        if ( s1 > 2.2 ) return _tau + 2;
+        else return _tau + 1;
+    }
+    return _tau + 1;
+}
+
+/**
+ *  available
+ *
+ *  @return true if data is ready else false
+ */
+bool AudioTuner::available( void ) {
+    __disable_irq();
+    bool flag = new_output;
+    if (flag) new_output = false;
+    __enable_irq();
+    return flag;
+}
+
+/**
+ *  read processes the data samples for the Yin algorithm.
+ *
+ *  @return frequency in hertz
+ */
+float AudioTuner::read( void ) {
+    return SAMPLE_RATE / data;
+}
+/**
+ *  Periodicity of the sampled signal from Yin algorithm from read function.
+ *
+ *  @return periodicity
+ */
+float AudioTuner::probability( void ) {
+    return periodicity;
+}
+/**
+ *  Initialise parameters.
+ *
+ *  @param thresh    Allowed uncertainty
+ */
+void AudioTuner::set_params( float thresh ) {
+    __disable_irq( );
+    //arm_cfft_radix4_init_q15(&fft_inst, 1024, 0, 1);
+    //arm_cfft_radix4_init_q15(&ifft_inst, 1024, 1, 1);
+    threshold = thresh;
+    periodicity = 0.0f;
+    block_count = 0;
+    enabled = true;
+    __enable_irq( );
+}

AudioTuner.h

+/* Audio Library for Teensy 3.X
+ * Copyright (c) 2015, Colin Duffy
+ *
+ * Development of this audio library was funded by PJRC.COM, LLC by sales of
+ * Teensy and Audio Adaptor boards.  Please support PJRC's efforts to develop
+ * open source software by purchasing Teensy or other PJRC products.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice, development funding notice, and this permission
+ * notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef AudioTuner_h_
+#define AudioTuner_h_
+
+#include "AudioStream.h"
+/****************************************************************/
+#define SAMPLE_RATE_DIVIDE_BY_1 1      // 44100    sample rate
+#define SAMPLE_RATE_DIVIDE_BY_2 2      // 22050    sample rate
+#define SAMPLE_RATE_DIVIDE_BY_4 4      // 11025    sample rate
+#define SAMPLE_RATE_DIVIDE_BY_8 8      // 5512.5   sample rate
+#define SAMPLE_RATE_DIVIDE_BY_16 16    // 2756.25  sample rate
+#define SAMPLE_RATE_DIVIDE_BY_32 32    // 1378.125 sample rate
+/****************************************************************
+ *              Safe to adjust these values below               *
+ ****************************************************************/
+// Adjust number of samples to collect in buffer here, also effects
+// convergence speed and resolution.
+#define NUM_SAMPLES 2048 // make a power of two
+
+// larger the divide-by, less resolution and lower the frequency for
+// a given number of samples that can be detected. Also effects
+// convergence speed.
+#define SAMPLE_SKIP SAMPLE_RATE_DIVIDE_BY_2
+/****************************************************************/
+
+class AudioTuner : public AudioStream
+{
+public:
+    AudioTuner( void ) : AudioStream( 1, inputQueueArray ),
+                                     enabled( false ), new_output(false),
+                                     next_buffer(1), process_buffer(false),
+                                     running_sum(0), block_count(0),
+                                     yin_idx(1)
+    {
+        
+        set_params( 0.05f );// threshold set 15ms
+    }
+    
+    /**
+     *  sets threshold value and window length
+     *
+     *  @param thresh
+     */
+    void set_params( float thresh );
+    
+    /**
+     *  triggers true when valid frequency is found
+     *
+     *  @return flag to indicate valid frequency is found
+     */
+    bool available( void );
+    /**
+     *  get frequency
+     *
+     *  @return frequency in hertz
+     */
+    float read( void );
+    
+    /**
+     *  get predicitity
+     *
+     *  @return probability of correct freq found
+     */
+    float probability( void );
+    /**
+     *  Audio Library calls this update function ~2.9ms
+     */
+    virtual void update( void );
+private:
+    /**
+     *  check the sampled data for fundmental frequency
+     *
+     *  @param yin  buffer to hold sum*tau value
+     *  @param rs   buffer to hold running sum for sampled window
+     *  @param head buffer index
+     *  @param tau  lag we are currently working on this gets incremented
+     *
+     *  @return tau
+     */
+    uint16_t estimate( int64_t *yin, int64_t *rs, uint16_t head, uint16_t tau );
+    
+    int16_t  buffer[NUM_SAMPLES*2] __attribute__ ( ( aligned ( 4 ) ) );
+    float    periodicity, threshold, data;
+    int64_t  rs_buffer[5], yin_buffer[5];
+    uint64_t running_sum;
+    uint16_t block_count, tau_global;
+    uint8_t  next_buffer, yin_idx;
+    bool     enabled, process_buffer;
+    volatile bool new_output;
+    audio_block_t *inputQueueArray[1];
+};
+#endif

README.md

+#Guitar Tuner for Teensy 3.1
+
+Software algorithm (YIN) for guitar and bass tuning using a Teensy Audio Library. This audio object's algorithm is somewhat memory and processor hungry but will allow you to detect lower frequencies than the Audio library's Goertzel algorithm will.

examples/Sample_Guitar_Tunning_Notes/Sample_Guitar_Tunning_Notes.ino

+/*
+ C     C#    D     Eb    E     F     F#    G     G#    A     Bb    B
+ 0 16.35 17.32 18.35 19.45 20.60 21.83 23.12 24.50 25.96 27.50 29.14 30.87
+ 1 32.70 34.65 36.71 38.89 41.20 43.65 46.25 49.00 51.91 55.00 58.27 61.74
+ 2 65.41 69.30 73.42 77.78 82.41 87.31 92.50 98.00 103.8 110.0 116.5 123.5
+ 3 130.8 138.6 146.8 155.6 164.8 174.6 185.0 196.0 207.7 220.0 233.1 246.9
+ 4 261.6 277.2 293.7 311.1 329.6 349.2 370.0 392.0 415.3 440.0 466.2 493.9
+ 5 523.3 554.4 587.3 622.3 659.3 698.5 740.0 784.0 830.6 880.0 932.3 987.8
+ 6 1047  1109  1175  1245  1319  1397  1480  1568  1661  1760  1865  1976
+ 7 2093  2217  2349  2489  2637  2794  2960  3136  3322  3520  3729  3951
+ 8 4186  4435  4699  4978  5274  5588  5920  6272  6645  7040  7459  7902
+ 
+ Guitar strings are E2=82.41Hz, A2=110Hz, D3=146.8Hz, G3=196Hz, B3=246.9Hz, E4=329.6Hz
+ 
+ Bass strings are (5th string) B0=30.87Hz, (4th string) E1=41.20Hz, A1=55Hz, D2=73.42Hz, G2=98Hz
+ 
+ This example tests the yin algorithm with actual notes from nylon string guitar recorded
+ as wav format at 16B @ 44100smpls/sec. Since the decay of the notes will be longer than what
+ the teensy can store in flash these notes are truncated to ~120,000B or about 1/2 of the whole
+ signal.
+ */
+#include <AudioTuner.h>
+#include <Audio.h>
+#include <Wire.h>
+#include <SPI.h>
+#include <SD.h>
+//---------------------------------------------------------------------------------------
+#include "e2_note.h"
+#include "a2_note.h"
+#include "d3_note.h"
+#include "g3_note.h"
+#include "b3_note.h"
+#include "e4_note.h"
+//---------------------------------------------------------------------------------------
+AudioTuner                tuner;
+AudioOutputAnalog         dac;
+AudioPlayMemory           wav_note;
+AudioMixer4               mixer;
+//---------------------------------------------------------------------------------------
+AudioConnection patchCord0(wav_note, 0, mixer, 0);
+AudioConnection patchCord1(mixer, 0, tuner, 0);
+AudioConnection patchCord2(mixer, 0, dac, 0);
+//---------------------------------------------------------------------------------------
+IntervalTimer playNoteTimer;
+
+void playNote(void) {
+    if (!wav_note.isPlaying()) {
+        wav_note.play(e2_note);
+        //wav_note.play(a2_note);
+        //wav_note.play(d3_note);
+        //wav_note.play(g3_note);
+        //wav_note.play(b3_note);
+        //wav_note.play(e4_note);
+        digitalWriteFast(LED_BUILTIN, !digitalReadFast(LED_BUILTIN));
+    }
+}
+//---------------------------------------------------------------------------------------
+void setup() {
+  // put your setup code here, to run once:
+  AudioMemory(4);
+  pinMode(LED_BUILTIN, OUTPUT);
+  playNoteTimer.begin(playNote, 1000);
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+  if (tuner.available()) {
+    float note = tuner.read();
+    float prob = tuner.probability();
+    Serial.printf("Note: %3.2f | Probility: %.2f\n", note, prob);
+  }
+
+}

examples/Sample_Guitar_Tunning_Notes/a2_note.h

+#include "Arduino.h"
+extern const unsigned int a2_note[53971];

examples/Sample_Guitar_Tunning_Notes/b3_note.h

+#include "Arduino.h"
+extern const unsigned int b3_note[53990];

examples/Sample_Guitar_Tunning_Notes/d3_note.h

+#include "Arduino.h"
+extern const unsigned int d3_note[53974];

examples/Sample_Guitar_Tunning_Notes/e2_note.h

+#include "Arduino.h"
+extern const unsigned int e2_note[53990];

examples/Sample_Guitar_Tunning_Notes/e4_note.h

+#include "Arduino.h"
+extern const unsigned int e4_note[53990];

examples/Sample_Guitar_Tunning_Notes/g3_note.h

+#include "Arduino.h"
+extern const unsigned int g3_note[53965];

examples/Simple_Sine/Handle_Commands.ino

+void handleCmds( String cmd ) {
+  String p = cmd;
+
+  if (p.startsWith("f ")) {
+    p.trim();
+    p = p.substring(2);
+    float t = p.toFloat();
+    Serial.print("new frequency: ");
+    Serial.println(t);
+    //AudioNoInterrupts();  // disable audio library momentarily
+    sine.frequency(p.toFloat());
+    //AudioInterrupts();    // enable, both tones will start together
+  }
+  else if (p.startsWith("a ")) {
+    p.trim();
+    p = p.substring(2);
+    float t = p.toFloat();
+    Serial.print("new amplitude: ");
+    Serial.println(t);
+    AudioNoInterrupts();  // disable audio library momentarily
+    sine.amplitude(p.toFloat());
+    AudioInterrupts();    // enable, both tones will start together
+  }
+}

examples/Simple_Sine/Simple_Sine.ino

+/*
+ C     C#    D     Eb    E     F     F#    G     G#    A     Bb    B
+ 0 16.35 17.32 18.35 19.45 20.60 21.83 23.12 24.50 25.96 27.50 29.14 30.87
+ 1 32.70 34.65 36.71 38.89 41.20 43.65 46.25 49.00 51.91 55.00 58.27 61.74
+ 2 65.41 69.30 73.42 77.78 82.41 87.31 92.50 98.00 103.8 110.0 116.5 123.5
+ 3 130.8 138.6 146.8 155.6 164.8 174.6 185.0 196.0 207.7 220.0 233.1 246.9
+ 4 261.6 277.2 293.7 311.1 329.6 349.2 370.0 392.0 415.3 440.0 466.2 493.9
+ 5 523.3 554.4 587.3 622.3 659.3 698.5 740.0 784.0 830.6 880.0 932.3 987.8
+ 6 1047  1109  1175  1245  1319  1397  1480  1568  1661  1760  1865  1976
+ 7 2093  2217  2349  2489  2637  2794  2960  3136  3322  3520  3729  3951
+ 8 4186  4435  4699  4978  5274  5588  5920  6272  6645  7040  7459  7902
+ 
+ Guitar strings are E2=82.41Hz, A2=110Hz, D3=146.8Hz, G3=196Hz, B3=246.9Hz, E4=329.6Hz
+ 
+ Bass strings are (5th string) B0=30.87Hz, (4th string) E1=41.20Hz, A1=55Hz, D2=73.42Hz, G2=98Hz
+ 
+ You can change the frequency by typing "f " + frequency in the serial monitor.
+ EX. "f 30.87"
+ 
+ You can change the amplitude by typing "a " + amplitude in the serial monitor. (0,1)
+ EX. "a .5"
+ */
+#include <AudioTuner.h>
+#include <Audio.h>
+#include <Wire.h>
+#include <SPI.h>
+#include <SD.h>
+
+AudioTuner                tuner;
+AudioSynthWaveformSine    sine;
+AudioOutputAnalog         dac;
+AudioMixer4               mixer;
+
+AudioConnection patchCord1(sine,  0, mixer, 0);
+AudioConnection patchCord2(mixer, 0, tuner, 0);
+AudioConnection patchCord3(mixer, 0, dac, 0);
+
+// hold serial commands
+char buffer[10];
+
+void setup() {
+  // put your setup code here, to run once:
+  AudioMemory(4);
+  sine.frequency(30.87);
+  sine.amplitude(1);
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+  if (tuner.available()) {
+    float note = tuner.read();
+    float prob = tuner.probability();
+    Serial.printf("Note: %3.2f | Probility: %.2f\n", note, prob);
+  }
+  
+  if (Serial.available()) {
+    Serial.readBytesUntil('\n', buffer, 10);
+    handleCmds( buffer );
+  }
+}

keywords.txt

+#######################################
+# Syntax Coloring Map AudioTuner.h
+#######################################
+
+#######################################
+# Datatypes (KEYWORD1)
+#######################################
+AudioTuner	KEYWORD1
+#######################################
+# Methods and Functions (KEYWORD2)
+#######################################
+AudioTuner	KEYWORD2
+available	KEYWORD2
+probability	KEYWORD2
+read	KEYWORD2
+#######################################
+# Instances (KEYWORD2)
+#######################################
+
+#######################################
+# Constants (LITERAL1)
+#######################################
+threshold	LITERAL1
+periodicity	LITERAL1
+tuner	LITERAL1