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Bug with IIR filter functions?

pechiinu
Beginner
392 Views
Hello.

Please forgive my English.

I am using ippsIIR_32f for filtering audio stream, and have a trouble with this function. When I pass the non-zero samplesto pSrc, the function works well. but when I pass zero samples, the processing becomes delayed.

Why? and How can I avoid this undesirable phenomenon?
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2 Replies
Chao_Y_Intel
Moderator
392 Views

HI,

Do you have any code that can show this problem? That will be helpful.

Thanks,
Chao

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pechiinu
Beginner
392 Views
Thank you for your reply, and please excuse me for being late to answer.

I'llgive a samplecode follow:

---
int iir(void)
{
int ret = 1;
int const input_length = 48000 * 24;
int const filter_length = FILTER_COEFFICIENTS_LENGTH;

Ipp32f *input = NULL;
Ipp32f *filter = NULL;
Ipp32f *output = NULL;

//
// zero-padding to input sequence except for the first sample
//
input = ippsMalloc_32f(input_length);
if (input==0) { goto error; }
for (size_t i=1; iinput = 0;
}
input[0] = 1;

//
// set filter coefficients
//
filter = ippsMalloc_32f(filter_length);
if (filter==0) { goto error; }
for (size_t i=0; ifilter = FilterCoefficients;
}

output = ippsMalloc_32f(input_length);
if (output==0) { goto error; }

{
IppsIIRState_32f *ctx;
DWORD start;
DWORD end;
DWORD elapsed;
IppStatus status;
status = ippsIIRInitAlloc_32f(&ctx, filter, (int)(filter_length/2-1), 0);
if (status != ippStsNoErr) {
printf("IIRInitAlloc failure.n");
goto error;
}

//
// start measuring
//
start = GetTickCount();
status = ippsIIR_32f(input, output, (int)input_length, ctx);

//
// stop measuring
//
end = GetTickCount();

elapsed = (end-start);
printf("input : time(ms)=%ld status=%dn"
, elapsed, status);

ippsIIRFree_32f(ctx);
}

ret = 0;
error:
if (input) { ippsFree(input); }
if (filter) { ippsFree(filter); }
if (output) { ippsFree(output); }

return ret;
}
---

Thank you.


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