topic Hi John, in Intel® Integrated Performance Primitives

ResamplePolyphaseFixed_32f crashes

John_H_ — Fri, 03 Feb 2017 14:44:21 GMT

I've been experimenting with using the polyphase resampler in IPP for resampling low sample rates without an integer resampling factor. (As an example, upsampling 400Hz to 480Hz).

I've created a simple test program which upsamples random data, similar to the example code in the documentation for ResamplePolyphaseFixed - however, the executable crashes with a segmentation fault somewhere inside the call to ResamplePolyphaseFixed.

The code, minus some debug output, is as follows:

int inputLength=400;
int outputLength=480;
int idealFilterLength=60;

float* input = new float[inputLength];
float* output = new float[outputLength];

for (int i = 0; i < inputLength; i++)
{
 input = (float)random / (float)RAND_MAX;
}

int pSize, pLen, pHeight;

ippsResamplePolyphaseFixedGetSize_32f(inputLength, outputLength, idealFilterLength, &pSize, &pLen, &pHeight, ippAlgHintFast)

IppsResamplingPolyphaseFixed_32f* spec;
spec = (IppsResamplingPolyphaseFixed_32f*)ippsMalloc_8u(pSize);

double pTime;
int outL;

ippsResamplePolyphaseFixed_32f(input, inputLength, output, 0.98f, &pTime, &outL, spec);

The program completes in gdb and valgrind, though valgrind reports a number of invalid reads inside ResamplePolyphaseFixed.

Any suggestions as to where I'm going wrong with this would be greatly appreciated.

Dear customer,

Zhen_Z_Intel — Sat, 04 Feb 2017 06:23:45 GMT

Dear customer,

You probably need to Initialize the structures for data resampling with the factor equal to inRate/outRate. Please use ippsResamplePolyphaseFixedInit_32f before resampling calculation. Here's a sample about how to use IPP polyphase resampling. You could refer to this link.

Best regards,
Fiona

Hi,

John_H_ — Mon, 06 Feb 2017 07:49:04 GMT

Hi,

I missed out the line which called that function when I was transcribing the code. This is the line after spec is allocated (at line 19 in the snippet in my original post):

ippsResamplePolyphaseFixedInit_32f(inputLength, outputLength, pLen, 0.95f, 8.0f, spec, ippAlgHintFast)

Hi John,

Zhen_Z_Intel — Wed, 08 Feb 2017 05:55:15 GMT

Hi John,

We are investigating on it. Thanks.

Best regards,
Fiona