amf_volumefletchermunson.c

ADI SHARC DSP 音频算法标准模块库

// Copyright(c) 2005 Analog Devices, Inc. All Rights Reserved.
// This software is proprietary and confidential to Analog Devices, Inc. and its licensors.

// File    : $Id: //depot/development/visualaudio/modules/2.5.0/SHARC/Source/AMF_VolumeFletcherMunson.c#3 $ 
// Part of : VisualAudio V2.5.0 
// Updated : $Date: 2006/10/12 $ by $Author: Fernando $



#include "AMF_VolumeFletcherMunson.h"
#include "VA_GeneralHelperFunctions.h"


void AMF_VolumeFletcherMunson_Render(AMF_VolumeFletcherMunson * restrict instance,float * restrict * buffers,int tickSize);

// NOTE: The C version of this function is for reference only (it is
//       intended just to show the general algorithm that the module
//       uses), and it may not have been fully tested
#if 0

SEG_MOD_FAST_CODE  void AMF_VolumeFletcherMunson_Render(AMF_VolumeFletcherMunson * restrict instance,float * restrict * buffers,int tickSize) {
    int i;
    float amp = instance->amp;
    float ampTarget = instance->ampTarget;
    float lowAmp = instance->lowAmp;
    float lowAmpTarget = instance->lowAmpTarget;
    float state1 = instance->aux->state1;
    float state2 = instance->aux->state2;
    float ampSmoothing = instance->ampSmoothing;
    float b0 = instance->b0;
    float b1 = instance->b1;

    float oneMinusRate = 1.0 - ampSmoothing;
    float tmp;
    float allPass;
    float *in = buffers[0]; 
    float *out = buffers[1];
    float *t = out;

        // the allpass filter, in -> out
    for (i=0; i<tickSize; i++) {
        tmp =  in[i]   - b1 * state1 - b0 * state2;
        t[i]   = b0 * tmp + b1 * state1 + state2;
        state2 = state1;
        state1 = tmp;
    }

        // smothing and Regalia-Mitra boost, out->out
    for (i=0; i<tickSize; i++) {
        // the smoothed amplitude and 'peaking' amplitude
        amp = amp * oneMinusRate + ampTarget * ampSmoothing;
        lowAmp = lowAmp * oneMinusRate + lowAmpTarget * ampSmoothing;
        
        // the Regalia-Mitra low boost
        out[i] = 0.5 * (amp * (in[i] + t[i]) + lowAmp * (in[i] - t[i]) );
    }
    instance->amp = amp;
    instance->lowAmp = lowAmp;
    instance->aux->state1 = state1;
    instance->aux->state2 = state2;
}
#endif

SEG_MOD_SLOW_CONST const AMF_ModuleClass AMFClassVolumeFletcherMunson = {
    
    /* Flags */
    0,

    /** Reference to render function. */
    (AMF_RenderFunction)AMF_VolumeFletcherMunson_Render,  // render function 

    /* Default bypass */
    (void *)0,

    /* Input descriptor - 1 input, and it is mono. */
    1, 0,

    /* Output descriptor - 1 output, and it is mono. */
    1, 0,
};

// Class-specific helper functions

// see AMF_SetFMGain() in VA_GeneralHelperFunctions.c
// also macro in AMF_VolumeFletcherMunson.h
//    AMF_VolumeFletcherMunson_SetGain()
// Function to set Volume VolumeFletcherMunson and VolumeFletcherMunson_S in dB (-192.0 - 0.0)
// Bass Boost calculated via 2nd order polynomial