Simple filtering in realtime - again...

Hi,

I keep working on my realtime app. 
I've been trying to find the cause of the troubles I had, but I'm still
stuck. 

I'm testing now a simple DC blocking filter (just a high pass filter); it
seems to work in terms of frequency, but it adds a very loud constant noise.
Here's a piece of the code - the rest of the main code is the
capture-playback routine with queue-  :

...

alcCaptureSamples(pCaptureDevice, Buffer,BUFFERSIZE / lBlockAlignment);

						
// This part is for separating left-right channels
int i;				
for(i=0;i<BUFFERSIZE/2;i++){
   entport[i]=float((Buffer[2*i])/32768);	// entport: input signal	- left
channel 
   //right channel not needed right now		
}									
						
DCfilter(entport,portnodc,BUFFERSIZE/2); // portnodc: input signal no dc

										
for(i=0;i<BUFFERSIZE/2;i++){
	BufferSalida[i]=ALshort(32767*portnodc.y[i]); // BufferSalida: Output
buffer
}
						
				
// Attaching data to buffer
alBufferData(BufferID[ulQueueCount], PlayFormat, BufferSalida, BUFFERSIZE/2,
lFrequency);

...

----------------------------------------

void DCfilter(samplesvector &x, nodctype &y, int size){

	int i;
	
	float a=0.995;
	for (i=0;i<size;i++){

		y.y[i]=x[i]-(y.xdcant)+(a*y.ydcant); //xdcant, ydcant: previous signal
values.
		y.xdcant=x[i];
		y.ydcant=y.y[i];
	}
}
----------------------------------------

where:
typedef float samplesvector[BUFFERSIZE/2];

typedef struct {
		samplesvector y;
		float xdcant;
		float ydcant;
		}nodctype;

----------------------------------------

I'm a little bit overwhelmed about not being able to make this work, so, any
help will be appreciated.
Any ideas?

Thanks in advance.
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