La reproducción simple de audio con FFT no funciona (dsPic33F)

Escribí una aplicación de audio de reproducción simple (hablas en el micrófono, se reproduce en los altavoces, solo para probar), funciona. Sin embargo, cuando agregué una FFT + FFT inversa, no es así, solo escucho una reacción sin ruido cuando hablo en el micrófono.

Por favor, ¿alguien ve un error?

#include<ADCChannelDrv.h>
#include<OCPWMDrv.h>
#include<sask.h>
#include<ex_sask_led.h>
#include<ex_sask_generic.h>
#include<dsp.h>


int AdcBuffer[ ADC_CHANNEL_DMA_BUFSIZE ] __attribute__((space(dma)));
int DacBuffer[ OCPWM_DMA_BUFSIZE ] __attribute__((space(dma)));

int main(void) {
ex_sask_init();

fractcomplex Frame[ 128 ];
fractional Output[ 128 ];
fractcomplex twiddleFactors[128/2];


/* FFT config */
int i = 0;
fractional *p_real;
fractcomplex *p_cmpx;

TwidFactorInit (7, &twiddleFactors[0], 0);  /* We need to do this only once at start-up */






/* Instantiate the drivers  */
ADCChannelHandle adcChannelHandle;
OCPWMHandle     ocPWMHandle;

/* Create the driver handles    */
ADCChannelHandle *MyADCHandle   = &adcChannelHandle;
OCPWMHandle     *MyDACHandle        = &ocPWMHandle;

ADCChannelInit (MyADCHandle, AdcBuffer);
OCPWMInit (MyDACHandle, DacBuffer);
ADCChannelStart(MyADCHandle);
OCPWMStart(MyDACHandle);

while (1) {
while (ADCChannelIsBusy(MyADCHandle));
ADCChannelRead  (MyADCHandle, (fractional*)Frame, ADC_BUFFER_SIZE);

p_real = &Frame[0].real ;
p_cmpx = &Frame[0] ;


for ( i = 0; i < 128; i++ )/* The FFT function requires input data */
{                   /* to be in the fractional fixed-point range [-0.5, +0.5]*/
        *p_real = *p_real >>1 ;     /* So, we shift all data samples by 1 bit to the right. */
        *p_real++;          /* Should you desire to optimize this process, perform */
}                   /* data scaling when first obtaining the time samples */
                        /* Or within the BitReverseComplex function source code */

p_real = &Frame[(128/2)-1].real ;   /* Set up pointers to convert real array */
p_cmpx = &Frame[128-1] ; /* to a complex array. The input array initially has all */
                        /* the real input samples followed by a series of zeros */


for ( i = 128; i > 0; i-- ) /* Convert the Real input sample array */
{                   /* to a Complex input sample array  */
        (*p_cmpx).real = (*p_real--);   /* We will simpy zero out the imaginary  */
        (*p_cmpx--).imag = 0x0000;  /* part of each data sample */
}





FFTComplexIP (7, &Frame[0], &twiddleFactors[0], COEFFS_IN_DATA);
IFFTComplexIP (7, &Frame[0], &twiddleFactors[0], COEFFS_IN_DATA);


for ( i = 0; i < 128; i++ )  /*Convert back */
{
        Output[i]=Frame[i].real;
}


OCPWMWrite  (MyDACHandle,Output, OCPWM_FRAME_SIZE);

}
return 0;
}