Import Overlapping FFT from Tympan

pull/11/head
boblark 4 years ago
parent 0232e199a8
commit fb807bbec6
  1. 177
      examples/FormantShifter_FD/AudioEffectFormantShiftFD_F32.h
  2. 219
      examples/FormantShifter_FD/FormantShifter_FD.ino
  3. 87
      examples/FormantShifter_FD/SerialManager.h
  4. 226
      examples/FrequencyShifter_FD/FrequencyShifter_FD.ino
  5. 87
      examples/FrequencyShifter_FD/SerialManager.h
  6. 125
      examples/LowpassFilter_FD/AudioEffectLowpassFD_F32.h
  7. 114
      examples/LowpassFilter_FD/LowpassFilter_FD.ino

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#ifndef _AudioEffectFormantShiftFD_F32_h
#define _AudioEffectFormantShiftFD_F32_h
#include "AudioStream_F32.h"
#include <arm_math.h>
#include "FFT_Overlapped_F32.h"
class AudioEffectFormantShiftFD_F32 : public AudioStream_F32
{
public:
//constructors...a few different options. The usual one should be: AudioEffectFormantShiftFD_F32(const AudioSettings_F32 &settings, const int _N_FFT)
AudioEffectFormantShiftFD_F32(void) : AudioStream_F32(1, inputQueueArray_f32) {};
AudioEffectFormantShiftFD_F32(const AudioSettings_F32 &settings) :
AudioStream_F32(1, inputQueueArray_f32) {
sample_rate_Hz = settings.sample_rate_Hz;
}
AudioEffectFormantShiftFD_F32(const AudioSettings_F32 &settings, const int _N_FFT) :
AudioStream_F32(1, inputQueueArray_f32) {
setup(settings, _N_FFT);
}
//destructor...release all of the memory that has been allocated
~AudioEffectFormantShiftFD_F32(void) {
if (complex_2N_buffer != NULL) delete complex_2N_buffer;
}
int setup(const AudioSettings_F32 &settings, const int _N_FFT) {
sample_rate_Hz = settings.sample_rate_Hz;
int N_FFT;
//setup the FFT and IFFT. If they return a negative FFT, it wasn't an allowed FFT size.
N_FFT = myFFT.setup(settings, _N_FFT); //hopefully, we got the same N_FFT that we asked for
if (N_FFT < 1) return N_FFT;
N_FFT = myIFFT.setup(settings, _N_FFT); //hopefully, we got the same N_FFT that we asked for
if (N_FFT < 1) return N_FFT;
//decide windowing
Serial.println("AudioEffectFormantShiftFD_F32: setting myFFT to use hanning...");
(myFFT.getFFTObject())->useHanningWindow(); //applied prior to FFT
#if 1
if (myIFFT.getNBuffBlocks() > 3) {
Serial.println("AudioEffectFormantShiftFD_F32: setting myIFFT to use hanning...");
(myIFFT.getIFFTObject())->useHanningWindow(); //window again after IFFT
}
#endif
//print info about setup
Serial.println("AudioEffectFormantShiftFD_F32: FFT parameters...");
Serial.print(" : N_FFT = "); Serial.println(N_FFT);
Serial.print(" : audio_block_samples = "); Serial.println(settings.audio_block_samples);
Serial.print(" : FFT N_BUFF_BLOCKS = "); Serial.println(myFFT.getNBuffBlocks());
Serial.print(" : IFFT N_BUFF_BLOCKS = "); Serial.println(myIFFT.getNBuffBlocks());
Serial.print(" : FFT use window = "); Serial.println(myFFT.getFFTObject()->get_flagUseWindow());
Serial.print(" : IFFT use window = "); Serial.println((myIFFT.getIFFTObject())->get_flagUseWindow());
//allocate memory to hold frequency domain data
complex_2N_buffer = new float32_t[2 * N_FFT];
//we're done. return!
enabled = 1;
return N_FFT;
}
//void setLowpassFreq_Hz(float freq_Hz) { lowpass_freq_Hz = freq_Hz; }
//float getLowpassFreq_Hz(void) { return lowpass_freq_Hz; }
float setScaleFactor(float scale_fac) {
if (scale_fac < 0.00001) scale_fac = 0.00001;
return shift_scale_fac = scale_fac;
}
float getScaleFactor(void) {
return shift_scale_fac;
}
virtual void update(void);
private:
int enabled = 0;
float32_t *complex_2N_buffer;
audio_block_f32_t *inputQueueArray_f32[1];
FFT_Overlapped_F32 myFFT;
IFFT_Overlapped_F32 myIFFT;
float lowpass_freq_Hz = 1000.f;
float sample_rate_Hz = AUDIO_SAMPLE_RATE;
float shift_scale_fac = 1.0; //how much to shift formants (frequency multiplier). 1.0 is no shift
};
void AudioEffectFormantShiftFD_F32::update(void)
{
//get a pointer to the latest data
audio_block_f32_t *in_audio_block = AudioStream_F32::receiveReadOnly_f32();
if (!in_audio_block) return;
//simply return the audio if this class hasn't been enabled
if (!enabled) {
AudioStream_F32::transmit(in_audio_block);
AudioStream_F32::release(in_audio_block);
return;
}
//convert to frequency domain
myFFT.execute(in_audio_block, complex_2N_buffer);
AudioStream_F32::release(in_audio_block); //We just passed ownership to myFFT, so release it here.
// ////////////// Do your processing here!!!
//define some variables
int fftSize = myFFT.getNFFT();
int N_2 = fftSize / 2 + 1;
int source_ind; // neg_dest_ind;
float source_ind_float, interp_fac;
float new_mag, scale;
float orig_mag[N_2];
//int max_source_ind = (int)(((float)N_2) * (10000.0 / (48000.0 / 2.0))); //highest frequency bin to grab from (Assuming 48kHz sample rate)
#if 1
float max_source_Hz = 10000.0; //highest frequency to use as source data
int max_source_ind = min(int(max_source_Hz / sample_rate_Hz * fftSize + 0.5),N_2);
#else
int max_source_ind = N_2; //this line causes this feature to be defeated
#endif
//get the magnitude for each FFT bin and store somewhere safes
arm_cmplx_mag_f32(complex_2N_buffer, orig_mag, N_2);
//now, loop over each bin and compute the new magnitude based on shifting the formants
for (int dest_ind = 1; dest_ind < N_2; dest_ind++) { //don't start at zero bin, keep it at its original
//what is the source bin for the new magnitude for this current destination bin
source_ind_float = (((float)dest_ind) / shift_scale_fac) + 0.5;
//source_ind = (int)(source_ind_float+0.5); //no interpolation but round to the neariest index
//source_ind = min(max(source_ind,1),N_2-1);
source_ind = min(max(1, (int)source_ind_float), N_2 - 2); //Chip: why -2 and not -1? Because later, for for the interpolation, we do a +1 and we want to stay within nyquist
interp_fac = source_ind_float - (float)source_ind;
interp_fac = max(0.0, interp_fac); //this will be used in the interpolation in a few lines
//what is the new magnitude
new_mag = 0.0; scale = 0.0;
if (source_ind < max_source_ind) {
//interpolate in the original magnitude vector to find the new magnitude that we want
//new_mag=orig_mag[source_ind]; //the magnitude that we desire
//scale = new_mag / orig_mag[dest_ind];//compute the scale factor
new_mag = orig_mag[source_ind];
new_mag += interp_fac * (orig_mag[source_ind] - orig_mag[source_ind + 1]);
scale = new_mag / orig_mag[dest_ind];
//apply scale factor
complex_2N_buffer[2 * dest_ind] *= scale; //real
complex_2N_buffer[2 * dest_ind + 1] *= scale; //imaginary
} else {
complex_2N_buffer[2 * dest_ind] = 0.0; //real
complex_2N_buffer[2 * dest_ind + 1] = 0.0; //imaginary
}
//zero out the lowest bin
complex_2N_buffer[0] = 0.0; //real
complex_2N_buffer[1] = 0.0; //imaginary
}
//rebuild the negative frequency space
myFFT.rebuildNegativeFrequencySpace(complex_2N_buffer); //set the negative frequency space based on the positive
// ///////////// End do your processing here
//call the IFFT
audio_block_f32_t *out_audio_block = myIFFT.execute(complex_2N_buffer); //out_block is pre-allocated in here.
//send the returned audio block. Don't issue the release command here because myIFFT will re-use it
AudioStream_F32::transmit(out_audio_block); //don't release this buffer because myIFFT re-uses it within its own code
return;
};
#endif

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// FormantShifter_FD
//
// Demonstrate formant shifting via frequency domain processin.
//
// Created: Chip Audette (OpenAudio) March 2019
//
// Approach:
// * Take samples in the time domain
// * Take FFT to convert to frequency domain
// * Manipulate the frequency bins to do the formant shifting
// * Take IFFT to convert back to time domain
// * Send samples back to the audio interface
//
// The amount of formant shifting is controled via the Serial link.
// It defaults to a modest upward shifting of the formants
//
// Built for the Tympan library for Teensy 3.6-based hardware
//
// MIT License. Use at your own risk.
//
#include <Tympan_Library.h>
#include "AudioEffectFormantShiftFD_F32.h" //the local file holding your custom function
#include "SerialManager.h"
//set the sample rate and block size
const float sample_rate_Hz = 44117.f; ; //24000 or 44117 (or other frequencies in the table in AudioOutputI2S_F32)
const int audio_block_samples = 128; //for freq domain processing choose a power of 2 (16, 32, 64, 128) but no higher than 128
AudioSettings_F32 audio_settings(sample_rate_Hz, audio_block_samples);
//create audio library objects for handling the audio
Tympan audioHardware(TympanRev::D); //do TympanRev::C or TympanRev::D
AudioInputI2S_F32 i2s_in(audio_settings); //Digital audio *from* the Tympan AIC.
AudioEffectFormantShiftFD_F32 formantShift(audio_settings); //create the frequency-domain processing block
AudioEffectGain_F32 gain1; //Applies digital gain to audio data.
AudioOutputI2S_F32 i2s_out(audio_settings); //Digital audio out *to* the Tympan AIC.
//Make all of the audio connections
AudioConnection_F32 patchCord1(i2s_in, 0, formantShift, 0); //use the Left input
AudioConnection_F32 patchCord2(formantShift, 0, gain1, 0); //connect to gain
AudioConnection_F32 patchCord3(gain1, 0, i2s_out, 0); //connect to the left output
AudioConnection_F32 patchCord4(gain1, 0, i2s_out, 1); //connect to the right output
//control display and serial interaction
bool enable_printCPUandMemory = false;
void togglePrintMemoryAndCPU(void) { enable_printCPUandMemory = !enable_printCPUandMemory; };
SerialManager serialManager(audioHardware);
#define mySerial audioHardware //audioHardware is a printable stream!
//inputs and levels
float input_gain_dB = 20.0f; //gain on the microphone
float formant_shift_gain_correction_dB = 0.0; //will be used to adjust for gain in formant shifter
float vol_knob_gain_dB = 0.0; //will be overridden by volume knob
void switchToPCBMics(void) {
mySerial.println("Switching to PCB Mics.");
audioHardware.inputSelect(TYMPAN_INPUT_ON_BOARD_MIC); // use the microphone jack - defaults to mic bias OFF
audioHardware.setInputGain_dB(input_gain_dB);
}
void switchToLineInOnMicJack(void) {
mySerial.println("Switching to Line-in on Mic Jack.");
audioHardware.inputSelect(TYMPAN_INPUT_JACK_AS_LINEIN); // use the microphone jack - defaults to mic bias OFF
audioHardware.setInputGain_dB(0.0);
}
void switchToMicInOnMicJack(void) {
mySerial.println("Switching to Mic-In on Mic Jack.");
audioHardware.inputSelect(TYMPAN_INPUT_JACK_AS_MIC); // use the microphone jack - defaults to mic bias OFF
audioHardware.setInputGain_dB(input_gain_dB);
}
// define the setup() function, the function that is called once when the device is booting
void setup() {
audioHardware.beginBothSerial(); delay(1000);
mySerial.println("FormantShifter: starting setup()...");
mySerial.print(" : sample rate (Hz) = "); mySerial.println(audio_settings.sample_rate_Hz);
mySerial.print(" : block size (samples) = "); mySerial.println(audio_settings.audio_block_samples);
// Audio connections require memory to work. For more
// detailed information, see the MemoryAndCpuUsage example
AudioMemory_F32(40, audio_settings);
// Configure the frequency-domain algorithm
int overlap_factor = 4; //set to 4 or 8 or either 75% overlap (4x) or 87.5% overlap (8x)
int N_FFT = audio_block_samples * overlap_factor;
formantShift.setup(audio_settings, N_FFT); //do after AudioMemory_F32();
formantShift.setScaleFactor(1.5); //1.0 is no formant shifting.
if (overlap_factor == 4) {
formant_shift_gain_correction_dB = -3.0;
} else if (overlap_factor == 8) {
formant_shift_gain_correction_dB = -9.0;
}
//Enable the Tympan to start the audio flowing!
audioHardware.enable(); // activate AIC
//setup DC-blocking highpass filter running in the ADC hardware itself
float cutoff_Hz = 60.0; //set the default cutoff frequency for the highpass filter
audioHardware.setHPFonADC(true,cutoff_Hz,audio_settings.sample_rate_Hz); //set to false to disble
//Choose the desired input
switchToPCBMics(); //use PCB mics as input
//switchToMicInOnMicJack(); //use Mic jack as mic input (ie, with mic bias)
//switchToLineInOnMicJack(); //use Mic jack as line input (ie, no mic bias)
//Set the desired volume levels
audioHardware.volume_dB(0); // headphone amplifier. -63.6 to +24 dB in 0.5dB steps.
// configure the blue potentiometer
servicePotentiometer(millis(),0); //update based on the knob setting the "0" is not relevant here.
//finish the setup by printing the help menu to the serial connections
serialManager.printHelp();
}
// define the loop() function, the function that is repeated over and over for the life of the device
void loop() {
//respond to Serial commands
while (Serial.available()) serialManager.respondToByte((char)Serial.read()); //USB Serial
//while (Serial1.available()) serialManager.respondToByte((char)Serial1.read()); //BT Serial
//check the potentiometer
servicePotentiometer(millis(), 100); //service the potentiometer every 100 msec
//check to see whether to print the CPU and Memory Usage
if (enable_printCPUandMemory) printCPUandMemory(millis(), 3000); //print every 3000 msec
} //end loop();
// ///////////////// Servicing routines
//servicePotentiometer: listens to the blue potentiometer and sends the new pot value
// to the audio processing algorithm as a control parameter
void servicePotentiometer(unsigned long curTime_millis, const unsigned long updatePeriod_millis) {
//static unsigned long updatePeriod_millis = 100; //how many milliseconds between updating the potentiometer reading?
static unsigned long lastUpdate_millis = 0;
static float prev_val = -1.0;
//has enough time passed to update everything?
if (curTime_millis < lastUpdate_millis) lastUpdate_millis = 0; //handle wrap-around of the clock
if ((curTime_millis - lastUpdate_millis) > updatePeriod_millis) { //is it time to update the user interface?
//read potentiometer
float val = float(audioHardware.readPotentiometer()) / 1023.0; //0.0 to 1.0
val = (1.0/9.0) * (float)((int)(9.0 * val + 0.5)); //quantize so that it doesn't chatter...0 to 1.0
//use the potentiometer value to control something interesting
if (abs(val - prev_val) > 0.05) { //is it different than befor?
prev_val = val; //save the value for comparison for the next time around
#if 0
//set the volume of the system
setVolKnobGain_dB(val*45.0f - 10.0f - input_gain_dB);
#else
//set the amount of formant shifting
float new_scale_fac = powf(2.0,(val-0.5)*2.0);
formantShift.setScaleFactor(new_scale_fac);
#endif
}
lastUpdate_millis = curTime_millis;
} // end if
} //end servicePotentiometer();
//This routine prints the current and maximum CPU usage and the current usage of the AudioMemory that has been allocated
void printCPUandMemory(unsigned long curTime_millis, unsigned long updatePeriod_millis) {
//static unsigned long updatePeriod_millis = 3000; //how many milliseconds between updating gain reading?
static unsigned long lastUpdate_millis = 0;
//has enough time passed to update everything?
if (curTime_millis < lastUpdate_millis) lastUpdate_millis = 0; //handle wrap-around of the clock
if ((curTime_millis - lastUpdate_millis) > updatePeriod_millis) { //is it time to update the user interface?
mySerial.print("printCPUandMemory: ");
mySerial.print("CPU Cur/Peak: ");
mySerial.print(audio_settings.processorUsage());
//mySerial.print(AudioProcessorUsage()); //if not using AudioSettings_F32
mySerial.print("%/");
mySerial.print(audio_settings.processorUsageMax());
//mySerial.print(AudioProcessorUsageMax()); //if not using AudioSettings_F32
mySerial.print("%, ");
mySerial.print("Dyn MEM Float32 Cur/Peak: ");
mySerial.print(AudioMemoryUsage_F32());
mySerial.print("/");
mySerial.print(AudioMemoryUsageMax_F32());
mySerial.println();
lastUpdate_millis = curTime_millis; //we will use this value the next time around.
}
}
void printGainSettings(void) {
mySerial.print("Gain (dB): ");
mySerial.print("Vol Knob = "); mySerial.print(vol_knob_gain_dB,1);
//mySerial.print(", Input PGA = "); mySerial.print(input_gain_dB,1);
mySerial.println();
}
void incrementKnobGain(float increment_dB) { //"extern" to make it available to other files, such as SerialManager.h
setVolKnobGain_dB(vol_knob_gain_dB+increment_dB);
}
void setVolKnobGain_dB(float gain_dB) {
vol_knob_gain_dB = gain_dB;
gain1.setGain_dB(vol_knob_gain_dB+formant_shift_gain_correction_dB);
printGainSettings();
}
float incrementFormantShift(float incr_factor) {
float cur_scale_factor = formantShift.getScaleFactor();
return formantShift.setScaleFactor(cur_scale_factor*incr_factor);
}

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#ifndef _SerialManager_h
#define _SerialManager_h
#include <Tympan_Library.h>
//now, define the Serial Manager class
class SerialManager {
public:
public:
SerialManager(Tympan &_audioHardware)
: audioHardware(_audioHardware)
{ };
//SerialManager(void)
//{ };
void respondToByte(char c);
void printHelp(void);
int N_CHAN;
float channelGainIncrement_dB = 2.5f;
float formantScaleIncrement = powf(2.0,1.0/6.0);
private:
Tympan &audioHardware;
};
#define thisSerial audioHardware
void SerialManager::printHelp(void) {
thisSerial.println();
thisSerial.println("SerialManager Help: Available Commands:");
thisSerial.println(" h: Print this help");
thisSerial.println(" g: Print the gain settings of the device.");
thisSerial.println(" C: Toggle printing of CPU and Memory usage");
thisSerial.println(" p: Switch to built-in PCB microphones");
thisSerial.println(" m: switch to external mic via mic jack");
thisSerial.println(" l: switch to line-in via mic jack");
thisSerial.print(" k: Increase the gain of all channels (ie, knob gain) by "); thisSerial.print(channelGainIncrement_dB); thisSerial.println(" dB");
thisSerial.print(" K: Decrease the gain of all channels (ie, knob gain) by ");thisSerial.print(-channelGainIncrement_dB); thisSerial.println(" dB");
thisSerial.print(" f: Raise formant shifting (change by "); thisSerial.print(formantScaleIncrement); thisSerial.println("x)");
thisSerial.print(" F: Lower formant shifting (change by "); thisSerial.print(1.0/formantScaleIncrement); thisSerial.println("x)"); thisSerial.println();
}
//functions in the main sketch that I want to call from here
extern void incrementKnobGain(float);
extern void printGainSettings(void);
extern void togglePrintMemoryAndCPU(void);
extern float incrementFormantShift(float);
extern void switchToPCBMics(void);
extern void switchToMicInOnMicJack(void);
extern void switchToLineInOnMicJack(void);
//switch yard to determine the desired action
void SerialManager::respondToByte(char c) {
//float old_val = 0.0, new_val = 0.0;
switch (c) {
case 'h': case '?':
printHelp(); break;
case 'g': case 'G':
printGainSettings(); break;
case 'k':
incrementKnobGain(channelGainIncrement_dB); break;
case 'K': //which is "shift k"
incrementKnobGain(-channelGainIncrement_dB); break;
case 'C': case 'c':
thisSerial.println("Received: toggle printing of memory and CPU usage.");
togglePrintMemoryAndCPU(); break;
case 'p':
switchToPCBMics(); break;
case 'm':
switchToMicInOnMicJack(); break;
case 'l':
switchToLineInOnMicJack();break;
case 'f':
{ float new_val = incrementFormantShift(formantScaleIncrement);
thisSerial.print("Recieved: new format scale = "); thisSerial.println(new_val);}
break;
case 'F':
{ float new_val = incrementFormantShift(1./formantScaleIncrement);
thisSerial.print("Recieved: new format scale = "); thisSerial.println(new_val);}
break;
}
}
#endif

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// FreqShifter_FD
//
// Demonstrate frequency shifting via frequency domain processin.
//
// Created: Chip Audette (OpenAudio) Aug 2019
//
// Approach: This processing is performed in the frequency domain.
// Frequencies can only be shifted by an integer number of bins,
// so small frequency shifts are not possible. For example, for
// a sample rate of 44.1kHz, and when using N=256, one can only
// shift frequencies in multiples of 44.1/256 = 172.3 Hz.
//
// This processing is performed in the frequency domain where
// we take the FFT, shift the bins upward or downward, take
// the IFFT, and listen to the results. In effect, this is
// single sideband modulation, which will sound very unnatural
// (like robot voices!). Maybe you'll like it, or maybe not.
// Probably not, unless you like weird. ;)
//
// You can shift frequencies upward or downward with this algorithm.
//
// Frequency Domain Processing:
// * Take samples in the time domain
// * Take FFT to convert to frequency domain
// * Manipulate the frequency bins to do the freqyebct shifting
// * Take IFFT to convert back to time domain
// * Send samples back to the audio interface
//
// Built for the Tympan library for Teensy 3.6-based hardware
//
// MIT License. Use at your own risk.
//
#include <Tympan_Library.h>
#include "SerialManager.h"
//set the sample rate and block size
const float sample_rate_Hz = 44117.f; ; //24000 or 44117 (or other frequencies in the table in AudioOutputI2S_F32)
const int audio_block_samples = 64; //for freq domain processing choose a power of 2 (16, 32, 64, 128) but no higher than 128
AudioSettings_F32 audio_settings(sample_rate_Hz, audio_block_samples);
//create audio library objects for handling the audio
Tympan audioHardware(TympanRev::D); //do TympanRev::C or TympanRev::D
AudioInputI2S_F32 i2s_in(audio_settings); //Digital audio *from* the Tympan AIC.
AudioEffectFreqShiftFD_F32 freqShift(audio_settings); //create the frequency-domain processing block
AudioEffectGain_F32 gain1; //Applies digital gain to audio data.
AudioOutputI2S_F32 i2s_out(audio_settings); //Digital audio out *to* the Tympan AIC.
//Make all of the audio connections
AudioConnection_F32 patchCord10(i2s_in, 0, freqShift, 0); //use the Left input
AudioConnection_F32 patchCord20(freqShift, 0, gain1, 0); //connect to gain
AudioConnection_F32 patchCord30(gain1, 0, i2s_out, 0); //connect to the left output
AudioConnection_F32 patchCord40(gain1, 0, i2s_out, 1); //connect to the right output
//control display and serial interaction
bool enable_printCPUandMemory = false;
void togglePrintMemoryAndCPU(void) { enable_printCPUandMemory = !enable_printCPUandMemory; };
SerialManager serialManager(audioHardware);
#define mySerial audioHardware //audioHardware is a printable stream!
//inputs and levels
float input_gain_dB = 15.0f; //gain on the microphone
float vol_knob_gain_dB = 0.0; //will be overridden by volume knob
void switchToPCBMics(void) {
mySerial.println("Switching to PCB Mics.");
audioHardware.inputSelect(TYMPAN_INPUT_ON_BOARD_MIC); // use the microphone jack - defaults to mic bias OFF
audioHardware.setInputGain_dB(input_gain_dB);
}
void switchToLineInOnMicJack(void) {
mySerial.println("Switching to Line-in on Mic Jack.");
audioHardware.inputSelect(TYMPAN_INPUT_JACK_AS_LINEIN); // use the microphone jack - defaults to mic bias OFF
audioHardware.setInputGain_dB(0.0);
}
void switchToMicInOnMicJack(void) {
mySerial.println("Switching to Mic-In on Mic Jack.");
audioHardware.inputSelect(TYMPAN_INPUT_JACK_AS_MIC); // use the microphone jack - defaults to mic bias OFF
audioHardware.setEnableStereoExtMicBias(true); //put the mic bias on both channels
audioHardware.setInputGain_dB(input_gain_dB);
}
// define the setup() function, the function that is called once when the device is booting
void setup() {
audioHardware.beginBothSerial(); delay(1000);
mySerial.println("freqShifter: starting setup()...");
mySerial.print(" : sample rate (Hz) = "); mySerial.println(audio_settings.sample_rate_Hz);
mySerial.print(" : block size (samples) = "); mySerial.println(audio_settings.audio_block_samples);
// Audio connections require memory to work. For more
// detailed information, see the MemoryAndCpuUsage example
AudioMemory_F32(40, audio_settings);
// Configure the FFT parameters algorithm
int overlap_factor = 4; //set to 2, 4 or 8...which yields 50%, 75%, or 87.5% overlap (8x)
int N_FFT = audio_block_samples * overlap_factor;
Serial.print(" : N_FFT = "); Serial.println(N_FFT);
freqShift.setup(audio_settings, N_FFT); //do after AudioMemory_F32();
//configure the frequency shifting
float shiftFreq_Hz = 750.0; //shift audio upward a bit
float Hz_per_bin = audio_settings.sample_rate_Hz / ((float)N_FFT);
int shift_bins = (int)(shiftFreq_Hz / Hz_per_bin + 0.5); //round to nearest bin
shiftFreq_Hz = shift_bins * Hz_per_bin;
Serial.print("Setting shift to "); Serial.print(shiftFreq_Hz); Serial.print(" Hz, which is "); Serial.print(shift_bins); Serial.println(" bins");
freqShift.setShift_bins(shift_bins); //0 is no ffreq shifting.
//Enable the Tympan to start the audio flowing!
audioHardware.enable(); // activate AIC
//setup DC-blocking highpass filter running in the ADC hardware itself
float cutoff_Hz = 60.0; //set the default cutoff frequency for the highpass filter
audioHardware.setHPFonADC(true,cutoff_Hz,audio_settings.sample_rate_Hz); //set to false to disble
//Choose the desired input
switchToPCBMics(); //use PCB mics as input
//switchToMicInOnMicJack(); //use Mic jack as mic input (ie, with mic bias)
//switchToLineInOnMicJack(); //use Mic jack as line input (ie, no mic bias)
//Set the desired volume levels
audioHardware.volume_dB(0); // headphone amplifier. -63.6 to +24 dB in 0.5dB steps.
// configure the blue potentiometer
servicePotentiometer(millis(),0); //update based on the knob setting the "0" is not relevant here.
//finish the setup by printing the help menu to the serial connections
serialManager.printHelp();
}
// define the loop() function, the function that is repeated over and over for the life of the device
void loop() {
//respond to Serial commands
while (Serial.available()) serialManager.respondToByte((char)Serial.read()); //USB Serial
//while (Serial1.available()) serialManager.respondToByte((char)Serial1.read()); //BT Serial
//check the potentiometer
servicePotentiometer(millis(), 100); //service the potentiometer every 100 msec
//check to see whether to print the CPU and Memory Usage
if (enable_printCPUandMemory) printCPUandMemory(millis(), 3000); //print every 3000 msec
} //end loop();
// ///////////////// Servicing routines
//servicePotentiometer: listens to the blue potentiometer and sends the new pot value
// to the audio processing algorithm as a control parameter
void servicePotentiometer(unsigned long curTime_millis, const unsigned long updatePeriod_millis) {
//static unsigned long updatePeriod_millis = 100; //how many milliseconds between updating the potentiometer reading?
static unsigned long lastUpdate_millis = 0;
static float prev_val = -1.0;
//has enough time passed to update everything?
if (curTime_millis < lastUpdate_millis) lastUpdate_millis = 0; //handle wrap-around of the clock
if ((curTime_millis - lastUpdate_millis) > updatePeriod_millis) { //is it time to update the user interface?
//read potentiometer
float val = float(audioHardware.readPotentiometer()) / 1023.0; //0.0 to 1.0
val = (1.0/9.0) * (float)((int)(9.0 * val + 0.5)); //quantize so that it doesn't chatter...0 to 1.0
//use the potentiometer value to control something interesting
if (abs(val - prev_val) > 0.05) { //is it different than befor?
prev_val = val; //save the value for comparison for the next time around
//change the volume
float vol_dB = 0.f + 30.0f * ((val - 0.5) * 2.0); //set volume as 0dB +/- 30 dB
audioHardware.print("Changing output volume to = "); audioHardware.print(vol_dB); audioHardware.println(" dB");
audioHardware.volume_dB(vol_dB);
}
lastUpdate_millis = curTime_millis;
} // end if
} //end servicePotentiometer();
//This routine prints the current and maximum CPU usage and the current usage of the AudioMemory that has been allocated
void printCPUandMemory(unsigned long curTime_millis, unsigned long updatePeriod_millis) {
//static unsigned long updatePeriod_millis = 3000; //how many milliseconds between updating gain reading?
static unsigned long lastUpdate_millis = 0;
//has enough time passed to update everything?
if (curTime_millis < lastUpdate_millis) lastUpdate_millis = 0; //handle wrap-around of the clock
if ((curTime_millis - lastUpdate_millis) > updatePeriod_millis) { //is it time to update the user interface?
mySerial.print("printCPUandMemory: ");
mySerial.print("CPU Cur/Peak: ");
mySerial.print(audio_settings.processorUsage());
mySerial.print("%/");
mySerial.print(audio_settings.processorUsageMax());
mySerial.print("%, ");
mySerial.print("Dyn MEM Float32 Cur/Peak: ");
mySerial.print(AudioMemoryUsage_F32());
mySerial.print("/");
mySerial.print(AudioMemoryUsageMax_F32());
mySerial.println();
lastUpdate_millis = curTime_millis; //we will use this value the next time around.
}
}
void printGainSettings(void) {
mySerial.print("Gain (dB): ");
mySerial.print("Vol Knob = "); mySerial.print(vol_knob_gain_dB,1);
//mySerial.print(", Input PGA = "); mySerial.print(input_gain_dB,1);
mySerial.println();
}
void incrementKnobGain(float increment_dB) { //"extern" to make it available to other files, such as SerialManager.h
setVolKnobGain_dB(vol_knob_gain_dB+increment_dB);
}
void setVolKnobGain_dB(float gain_dB) {
vol_knob_gain_dB = gain_dB;
gain1.setGain_dB(vol_knob_gain_dB);
printGainSettings();
}
int incrementFreqShift(int incr_factor) {
int cur_shift_bins = freqShift.getShift_bins();
return freqShift.setShift_bins(cur_shift_bins + incr_factor);
}

@ -0,0 +1,87 @@
#ifndef _SerialManager_h
#define _SerialManager_h
#include <Tympan_Library.h>
//now, define the Serial Manager class
class SerialManager {
public:
public:
SerialManager(Tympan &_audioHardware)
: audioHardware(_audioHardware)
{ };
//SerialManager(void)
//{ };
void respondToByte(char c);
void printHelp(void);
int N_CHAN;
float channelGainIncrement_dB = 2.5f;
int freq_shift_increment = 1;
private:
Tympan &audioHardware;
};
#define thisSerial audioHardware
void SerialManager::printHelp(void) {
thisSerial.println();
thisSerial.println("SerialManager Help: Available Commands:");
thisSerial.println(" h: Print this help");
thisSerial.println(" g: Print the gain settings of the device.");
thisSerial.println(" C: Toggle printing of CPU and Memory usage");
thisSerial.println(" p: Switch to built-in PCB microphones");
thisSerial.println(" m: switch to external mic via mic jack");
thisSerial.println(" l: switch to line-in via mic jack");
thisSerial.print(" k: Increase the gain of all channels (ie, knob gain) by "); thisSerial.print(channelGainIncrement_dB); thisSerial.println(" dB");
thisSerial.print(" K: Decrease the gain of all channels (ie, knob gain) by ");thisSerial.print(-channelGainIncrement_dB); thisSerial.println(" dB");
thisSerial.print(" f: Raise freq shifting (change by "); thisSerial.print(freq_shift_increment); thisSerial.println(" bins)");
thisSerial.print(" F: Lower freq shifting (change by "); thisSerial.print(-freq_shift_increment); thisSerial.println(" bins)"); thisSerial.println();
}
//functions in the main sketch that I want to call from here
extern void incrementKnobGain(float);
extern void printGainSettings(void);
extern void togglePrintMemoryAndCPU(void);
extern int incrementFreqShift(int);
extern void switchToPCBMics(void);
extern void switchToMicInOnMicJack(void);
extern void switchToLineInOnMicJack(void);
//switch yard to determine the desired action
void SerialManager::respondToByte(char c) {
//float old_val = 0.0, new_val = 0.0;
switch (c) {
case 'h': case '?':
printHelp(); break;
case 'g': case 'G':
printGainSettings(); break;
case 'k':
incrementKnobGain(channelGainIncrement_dB); break;
case 'K': //which is "shift k"
incrementKnobGain(-channelGainIncrement_dB); break;
case 'C': case 'c':
thisSerial.println("Received: toggle printing of memory and CPU usage.");
togglePrintMemoryAndCPU(); break;
case 'p':
switchToPCBMics(); break;
case 'm':
switchToMicInOnMicJack(); break;
case 'l':
switchToLineInOnMicJack();break;
case 'f':
{ int new_val = incrementFreqShift(freq_shift_increment);
thisSerial.print("Recieved: new freq shift = "); thisSerial.println(new_val);}
break;
case 'F':
{ int new_val = incrementFreqShift(-freq_shift_increment);
thisSerial.print("Recieved: new freq shift = "); thisSerial.println(new_val);}
break;
}
}
#endif

@ -0,0 +1,125 @@
/*
* This include is NOT global to the OpenAudio library, but supports
* LowpassFilter_FD.ino
*/
#ifndef _AudioEffectLowpassFD_F32_h
#define _AudioEffectLowpassFD_F32_h
#include "AudioStream_F32.h"
#include <arm_math.h>
#include "FFT_Overlapped_OA_F32.h"
class AudioEffectLowpassFD_F32 : public AudioStream_F32
{
public:
// constructors...a few different options. The usual one should be:
// AudioEffectLowpassFD_F32(const AudioSettings_F32 &settings, const int _N_FFT)
AudioEffectLowpassFD_F32(void) : AudioStream_F32(1, inputQueueArray_f32) {};
AudioEffectLowpassFD_F32(const AudioSettings_F32 &settings) :
AudioStream_F32(1, inputQueueArray_f32) { sample_rate_Hz = settings.sample_rate_Hz; }
AudioEffectLowpassFD_F32(const AudioSettings_F32 &settings, const int _N_FFT) :
AudioStream_F32(1, inputQueueArray_f32) { setup(settings,_N_FFT); }
//destructor...release all of the memory that has been allocated
~AudioEffectLowpassFD_F32(void) {
if (complex_2N_buffer != NULL) delete complex_2N_buffer;
}
int setup(const AudioSettings_F32 &settings, const int _N_FFT) {
sample_rate_Hz = settings.sample_rate_Hz;
int N_FFT;
//setup the FFT and IFFT. If they return a negative FFT, it wasn't an allowed FFT size.
N_FFT = myFFT.setup(settings,_N_FFT); //hopefully, we got the same N_FFT that we asked for
if (N_FFT < 1) return N_FFT;
N_FFT = myIFFT.setup(settings,_N_FFT); //hopefully, we got the same N_FFT that we asked for
if (N_FFT < 1) return N_FFT;
//decide windowing
Serial.println("AudioEffectLowpassFD_F32: setting myFFT to use hanning...");
(myFFT.getFFTObject())->useHanningWindow(); //applied prior to FFT
//if (myIFFT.getNBuffBlocks() > 3) {
// Serial.println("AudioEffectLowpassFD_F32: setting myIFFT to use hanning...");
// (myIFFT.getIFFTObject())->useHanningWindow(); //window again after IFFT
//}
//print info about setup
Serial.println("AudioEffectLowpassFD_F32: FFT parameters...");
Serial.print(" : N_FFT = "); Serial.println(N_FFT);
Serial.print(" : audio_block_samples = "); Serial.println(settings.audio_block_samples);
Serial.print(" : FFT N_BUFF_BLOCKS = "); Serial.println(myFFT.getNBuffBlocks());
Serial.print(" : IFFT N_BUFF_BLOCKS = "); Serial.println(myIFFT.getNBuffBlocks());
Serial.print(" : FFT use window = "); Serial.println(myFFT.getFFTObject()->get_flagUseWindow());
Serial.print(" : IFFT use window = "); Serial.println((myIFFT.getIFFTObject())->get_flagUseWindow());
//allocate memory to hold frequency domain data
complex_2N_buffer = new float32_t[2*N_FFT];
//we're done. return!
enabled=1;
return N_FFT;
}
void setLowpassFreq_Hz(float freq_Hz) { lowpass_freq_Hz = freq_Hz; }
float getLowpassFreq_Hz(void) { return lowpass_freq_Hz; }
virtual void update(void);
private:
int enabled=0;
float32_t *complex_2N_buffer;
audio_block_f32_t *inputQueueArray_f32[1];
FFT_Overlapped_OA_F32 myFFT;
IFFT_Overlapped_OA_F32 myIFFT;
float lowpass_freq_Hz = 1000.f;
float sample_rate_Hz = AUDIO_SAMPLE_RATE;
};
void AudioEffectLowpassFD_F32::update(void)
{
//get a pointer to the latest data
audio_block_f32_t *in_audio_block = AudioStream_F32::receiveReadOnly_f32();
if (!in_audio_block) return;
//simply return the audio if this class hasn't been enabled
if (!enabled) { AudioStream_F32::transmit(in_audio_block); AudioStream_F32::release(in_audio_block); return; }
//convert to frequency domain
myFFT.execute(in_audio_block, complex_2N_buffer);
AudioStream_F32::release(in_audio_block); //We just passed ownership to myFFT, so release it here.
// ////////////// Do your processing here!!!
//this is lowpass, so zero the bins above the cutoff
int NFFT = myFFT.getNFFT();
int nyquist_bin = NFFT/2 + 1;
float bin_width_Hz = sample_rate_Hz / ((float)NFFT);
int cutoff_bin = (int)(lowpass_freq_Hz / bin_width_Hz + 0.5); //the 0.5 is so that it rounds instead of truncates
if (cutoff_bin < nyquist_bin) {
for (int i=cutoff_bin; i < nyquist_bin; i++) { //only do positive frequency space...will rebuild the neg freq space later
#if 0
//zero out the bins (silence
complex_2N_buffer[2*i] = 0.0f; //real
complex_2N_buffer[2*i+1]= 0.0f; //imaginary
#else
//attenuate by 30 dB
complex_2N_buffer[2*i] *= 0.03f; //real
complex_2N_buffer[2*i+1] *= 0.03f; //imaginary
#endif
}
}
myFFT.rebuildNegativeFrequencySpace(complex_2N_buffer); //set the negative frequency space based on the positive
// ///////////// End do your processing here
//call the IFFT
audio_block_f32_t *out_audio_block = myIFFT.execute(complex_2N_buffer); //out_block is pre-allocated in here.
//send the returned audio block. Don't issue the release command here because myIFFT will re-use it
AudioStream_F32::transmit(out_audio_block); //don't release this buffer because myIFFT re-uses it within its own code
return;
};
#endif

@ -0,0 +1,114 @@
/* LowpassFilter_FD.ino
*
* Demonstrate audio procesing in the frequency domain.
*
* Created: Chip Audette Sept-Oct 2016 for Tympan Library
* Approach:
* Take samples in the time domain
* Take FFT to convert to frequency domain
* Manipulate the frequency bins as desired (LP filter? BP filter? Formant shift?)
* Take IFFT to convert back to time domain
* Send samples back to the audio interface
*
* Assumes the use of the Audio library from PJRC
*
* Adapted to OpenAudio, "_OA". June 2020 Bob Larkin.
* This changed from direct F32 AudioInputI2S to I16 Teensy Audio Library
* versions with Chip Audette's AudioConvert objects. Also removed volume
* control. Class and file names are isolated from other libraries by "_OA".
* Tested T3.6 and T4.0 with PJRC Teensy Audio Adaptor.
*
* Ref: https://github.com/Tympan/Tympan_Library
* https://github.com/Tympan/Tympan_Library/tree/master/examples/04-FrequencyDomain/LowpassFilter_FD
* https://forum.pjrc.com/threads/40188-Fast-Convolution-filtering-in-floating-point-with-Teensy-3-6
* https://forum.pjrc.com/threads/40590-Teensy-Convolution-SDR-(Software-Defined-Radio)
*
* This example code is in the public domain (MIT License)
*/
#include "SD.h"
#include "AudioStream_F32.h"
#include <OpenAudio_ArduinoLibrary.h>
#include "AudioEffectLowpassFD_F32.h" // the local file holding your custom function
//set the sample rate and block size
const float sample_rate_Hz = 44117.f;
const int audio_block_samples = 128; // for freq domain processing, choose 16, 32, 64 or 128
AudioSettings_F32 audio_settings(sample_rate_Hz, audio_block_samples);
//create audio library objects for handling the audio
AudioInputI2S i2sIn;
AudioConvert_I16toF32 cnvrt1;
AudioSynthWaveformSine_F32 sinewave(audio_settings);
AudioEffectLowpassFD_F32 audioEffectLowpassFD(audio_settings); //create the frequency-domain processing block
AudioConvert_F32toI16 cnvrt2;
AudioOutputI2S i2sOut;
AudioControlSGTL5000 codec;
//Make all of the audio connections if 1 for Codec input, 0 for internally generated sine wave
#if 1
AudioConnection patchCord1(i2sIn, 0, cnvrt1, 0); // connect to Left codec, 16-bit
AudioConnection_F32 patchCord2(cnvrt1, 0, audioEffectLowpassFD, 0); // Now converted to float
#else
AudioConnection_F32 patchCord1(sinewave, 0, audioEffectLowpassFD, 0); // connect sine to filter
#endif
AudioConnection_F32 patchCord5(audioEffectLowpassFD, 0, cnvrt2, 0); // filtered output
AudioConnection patchCord6(cnvrt2, 0, i2sOut, 0); // Left channel
int is_windowing_active = 0;
void setup() {
//begin the serial comms (for debugging), any baud rate
Serial.begin(1); delay(500);
Serial.println("FrequencyDomainDemo2: starting setup()...");
Serial.print(" : sample rate (Hz) = "); Serial.println(audio_settings.sample_rate_Hz);
Serial.print(" : block size (samples) = "); Serial.println(audio_settings.audio_block_samples);
// Audio connections require memory to work. For more
// detailed information, see the MemoryAndCpuUsage example
AudioMemory(10); AudioMemory_F32(20, audio_settings);
codec.enable();
// Configure the frequency-domain algorithm
int N_FFT = 1024;
audioEffectLowpassFD.setup(audio_settings,N_FFT); //do after AudioMemory_F32();
sinewave.frequency(1000.0f);
sinewave.amplitude(0.025f);
Serial.println("Setup complete.");
}
void loop() {
}
//This routine prints the current and maximum CPU usage and the current usage of the AudioMemory that has been allocated
void printCPUandMemory(unsigned long curTime_millis, unsigned long updatePeriod_millis) {
//static unsigned long updatePeriod_millis = 3000; //how many milliseconds between updating gain reading?
static unsigned long lastUpdate_millis = 0;
//has enough time passed to update everything?
if (curTime_millis < lastUpdate_millis) lastUpdate_millis = 0; //handle wrap-around of the clock
if ((curTime_millis - lastUpdate_millis) > updatePeriod_millis) { //is it time to update the user interface?
Serial.print("printCPUandMemory: ");
Serial.print("CPU Cur/Peak: ");
Serial.print(audio_settings.processorUsage());
//Serial.print(AudioProcessorUsage()); //if not using AudioSettings_F32
Serial.print("%/");
Serial.print(audio_settings.processorUsageMax());
//Serial.print(AudioProcessorUsageMax()); //if not using AudioSettings_F32
Serial.print("%, ");
Serial.print("Dyn MEM Int16 Cur/Peak: ");
Serial.print(AudioMemoryUsage());
Serial.print("/");
Serial.print(AudioMemoryUsageMax());
Serial.print(", ");
Serial.print("Dyn MEM Float32 Cur/Peak: ");
Serial.print(AudioMemoryUsage_F32());
Serial.print("/");
Serial.print(AudioMemoryUsageMax_F32());
Serial.println();
lastUpdate_millis = curTime_millis; //we will use this value the next time around.
}
}
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