OpenAudio_ArduinoLibrary/AudioEffectCompWDRC_F32.h

/*
 * AudioEffectCompWDR_F32: Wide Dynamic Rnage Compressor
 * 
 * Created: Chip Audette (OpenAudio) Feb 2017
 * Derived From: WDRC_circuit from CHAPRO from BTNRC: https://github.com/BTNRH/chapro
 *     As of Feb 2017, CHAPRO license is listed as "Creative Commons?"
 * 
 * MIT License.  Use at your own risk.
 * 
 */

#ifndef _AudioEffectCompWDRC_F32
#define _AudioEffectCompWDRC_F32

#include <Arduino.h>
#include <AudioStream_F32.h>
#include <arm_math.h>
#include <AudioCalcEnvelope_F32.h>
#include "AudioCalcGainWDRC_F32.h"  //has definition of CHA_WDRC


// from CHAPRO cha_ff.h
#define DSL_MXCH 32              // maximum number of channels
typedef struct {
    float attack;               // attack time (ms)
    float release;              // release time (ms)
    float maxdB;                // maximum signal (dB SPL)
    int ear;                     // 0=left, 1=right
    int nchannel;                // number of channels
    float cross_freq[DSL_MXCH]; // cross frequencies (Hz)
    float tkgain[DSL_MXCH];     // compression-start gain
    float cr[DSL_MXCH];         // compression ratio
    float tk[DSL_MXCH];         // compression-start kneepoint
    float bolt[DSL_MXCH];       // broadband output limiting threshold
} CHA_DSL;

typedef struct {
    float alfa;                 // attack constant (not time)
    float beta;                 // release constant (not time
    float fs;                   // sampling rate (Hz)
    float maxdB;                // maximum signal (dB SPL)
    float tkgain;               // compression-start gain
    float tk;                   // compression-start kneepoint
    float cr;                   // compression ratio
    float bolt;                 // broadband output limiting threshold
} CHA_DVAR_t;


class AudioEffectCompWDRC_F32 : public AudioStream_F32
{
  public:
    AudioEffectCompWDRC_F32(void): AudioStream_F32(1,inputQueueArray) { //need to modify this for user to set sample rate
      setSampleRate_Hz(AUDIO_SAMPLE_RATE);
      setDefaultValues();
    }

    AudioEffectCompWDRC_F32(AudioSettings_F32 settings): AudioStream_F32(1,inputQueueArray) { //need to modify this for user to set sample rate
      setSampleRate_Hz(settings.sample_rate_Hz);
      setDefaultValues();
    }

    //here is the method called automatically by the audio library
    void update(void) {
      //receive the input audio data
      audio_block_f32_t *block = AudioStream_F32::receiveReadOnly_f32();
      if (!block) return;
      
      //allocate memory for the output of our algorithm
      audio_block_f32_t *out_block = AudioStream_F32::allocate_f32();
      if (!out_block) return;
      
      //do the algorithm
      cha_agc_channel(block->data, out_block->data, block->length);
      
      // transmit the block and release memory
      AudioStream_F32::transmit(out_block); // send the FIR output
      AudioStream_F32::release(out_block);
      AudioStream_F32::release(block);
    }


    //here is the function that does all the work
    void cha_agc_channel(float *input, float *output, int cs) {  
      //compress(input, output, cs, &prev_env,
      //  CHA_DVAR.alfa, CHA_DVAR.beta, CHA_DVAR.tkgain, CHA_DVAR.tk, CHA_DVAR.cr, CHA_DVAR.bolt, CHA_DVAR.maxdB);
      compress(input, output, cs);
    }

    //void compress(float *x, float *y, int n, float *prev_env,
    //    float &alfa, float &beta, float &tkgn, float &tk, float &cr, float &bolt, float &mxdB)
     void compress(float *x, float *y, int n)    
     //x, input, audio waveform data
     //y, output, audio waveform data after compression
     //n, input, number of samples in this audio block
    {        
        // find smoothed envelope
        audio_block_f32_t *envelope_block = AudioStream_F32::allocate_f32();
        if (!envelope_block) return;
        calcEnvelope.smooth_env(x, envelope_block->data, n);
        //float *xpk = envelope_block->data; //get pointer to the array of (empty) data values

        //calculate gain
        audio_block_f32_t *gain_block = AudioStream_F32::allocate_f32();
        if (!gain_block) return;
        calcGain.calcGainFromEnvelope(envelope_block->data, gain_block->data, n);
        
        //apply gain
        arm_mult_f32(x, gain_block->data, y, n);

        // release memory
        AudioStream_F32::release(envelope_block);
        AudioStream_F32::release(gain_block);
    }


    void setDefaultValues(void) {
      //set default values...taken from CHAPRO, GHA_Demo.c  from "amplify()"...ignores given sample rate
      //assumes that the sample rate has already been set!!!!
      CHA_WDRC gha = {1.0f, // attack time (ms)
        50.0f,     // release time (ms)
        24000.0f,  // fs, sampling rate (Hz), THIS IS IGNORED!
        119.0f,    // maxdB, maximum signal (dB SPL)
        0.0f,      // tkgain, compression-start gain
        105.0f,    // tk, compression-start kneepoint
        10.0f,     // cr, compression ratio
        105.0f     // bolt, broadband output limiting threshold
      };
      setParams_from_CHA_WDRC(&gha);
    }

    //set all of the parameters for the compressor using the CHA_WDRC structure
    //assumes that the sample rate has already been set!!!
    void setParams_from_CHA_WDRC(CHA_WDRC *gha) {
      //configure the envelope calculator...assumes that the sample rate has already been set!
      calcEnvelope.setAttackRelease_msec(gha->attack,gha->release); //these are in milliseconds

      //configure the compressor
      calcGain.setParams_from_CHA_WDRC(gha);
    }

    //set all of the user parameters for the compressor
    //assumes that the sample rate has already been set!!!
    void setParams(float attack_ms, float release_ms, float maxdB, float tkgain, float comp_ratio, float tk, float bolt) {
      
      //configure the envelope calculator...assumes that the sample rate has already been set!
      calcEnvelope.setAttackRelease_msec(attack_ms,release_ms);

      //configure the WDRC gains
      calcGain.setParams(maxdB, tkgain, comp_ratio, tk, bolt);
    }

    void setSampleRate_Hz(const float _fs_Hz) {
      //pass this data on to its components that care
      given_sample_rate_Hz = _fs_Hz;
      calcEnvelope.setSampleRate_Hz(_fs_Hz);
    }

    float getCurrentLevel_dB(void) { return AudioCalcGainWDRC_F32::db2(calcEnvelope.getCurrentLevel()); }  //this is 20*log10(abs(signal)) after the envelope smoothing

    AudioCalcEnvelope_F32 calcEnvelope;
    AudioCalcGainWDRC_F32 calcGain;
    
  private:
    audio_block_f32_t *inputQueueArray[1];
    float given_sample_rate_Hz;
};


#endif