/* FormantShifter_FD.ino * * 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 * * Adapt to OpenAudio Library - Bob Larkin June 2020 * Ref: http://iris.elf.stuba.sk/JEEEC/data/pdf/1_110-08.pdf * * MIT License. Use at your own risk. * */ #include "AudioStream_F32.h" #include "OpenAudio_ArduinoLibrary.h" #include "AudioEffectFormantShiftFD_OA_F32.h" //the local file holding your custom function #include "SerialManager_OA.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 AudioInputI2S i2sIn; AudioConvert_I16toF32 cnvrt1; AudioEffectFormantShiftFD_F32 formantShift(audio_settings); //create the frequency-domain processing block AudioEffectGain_F32 gain1; //Applies digital gain to audio data. AudioConvert_F32toI16 cnvrt2; AudioOutputI2S i2sOut; AudioControlSGTL5000 codec; //Make all of the audio connections AudioConnection patchCord1(i2sIn, 0, cnvrt1, 0); // connect to Left codec, 16-bit AudioConnection_F32 patchCord2(cnvrt1, 0, formantShift, 0); AudioConnection_F32 patchCord2(formantShift, 0, gain1, 0); //connect to gain AudioConnection_F32 patchCord3(gain1, 0, cnvrt2, 0); //connect to the left output AudioConnection patchCord6(cnvrt2, 0, i2sOut, 0); //control display and serial interaction bool enable_printCPUandMemory = false; void togglePrintMemoryAndCPU(void) { enable_printCPUandMemory = !enable_printCPUandMemory; }; SerialManager_OA SerialManager_OA(audioHardware); //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 // define the setup() function, the function that is called once when the device is booting void setup() { Serial.begin(1); 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(3); // I16 type 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; } codec.enable(); // activate AIC //setup DC-blocking highpass filter running in the ADC hardware itself //Choose the desired input //Set the desired volume levels audioHardware.volume_dB(0); // headphone amplifier. -63.6 to +24 dB in 0.5dB steps. //finish the setup by printing the help menu to the serial connections Serial.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_OA.respondToByte((char)Serial.read()); //USB Serial //while (Serial1.available()) SerialManager_OA.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 #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? 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 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. } } void printGainSettings(void) { Serial.print("Gain (dB): "); Serial.print("Vol Knob = "); Serial.print(vol_knob_gain_dB,1); //Serial.print(", Input PGA = "); Serial.print(input_gain_dB,1); Serial.println(); } void incrementKnobGain(float increment_dB) { //"extern" to make it available to other files, such as SerialManager_OA.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); }