Intel® Integrated Performance Primitives
Community support and discussions relating to developing high-performance vision, signal, security, and storage applications.
Announcements
Welcome to the Intel Community. If you get an answer you like, please mark it as an Accepted Solution to help others. Thank you!

ippsResamplePolyphaseFixed (IPP 7.1)

Bob_Kirnum
Beginner
99 Views

I'm trying to use 'ippsResamplePolyphaseFixed' based on the sample code I found here.  Most makes sense and I have things almost working.  The problem I have (in addition to the outdated API being used in the sample code) is that I am working on sample frames processed in real time as opposed to file I/O.  That is, I am not reading a chunk from a file and resampling, I am reading a smaller chunk from a media stream (i.e. roughly 60 msec at 11kHz) and converting to an even smaller chunk (8kHz).  The example code uses a base buffer size of 4096 samples and a history of 128 samples . . .

int bufsize=4096;

int history=128;

Where do these values come from?  If I am providing input chunks of 660 samples should the buffsize / history values change or do I need to fill the buffer with more samples before trying to extract the converted samples?  The end result of my current implementation is that about 90% of the chunk is converted properly but I am seeing about 10% of trailing silence in the output for each 60 msec chunk.

Thanks Bob

0 Kudos
1 Reply
Igor_A_Intel
Employee
99 Views

Hi Bob,

this functionality doesn't support separate delay line as, for example, FIRMR functions - so there is detailed description in the manual how to provide right conditions for correct function work:"Input vector with indices less thanpTime[0]contains the history data of filters. The history length is equal toflen/2 forippsResamplePolyphaseFixedfunction , and [1/2window*max(1, 1/factor)]+1 forippsResamplePolyphasefunction. Hereflenis the filter length andwindowis the size of the ideal lowpass filter window. The input vector must contain the same number of elements with indices greater thanpTime[0] +lenfor the right filter wing for the last element."

input block size of 4096 is just for example - you can use any other, history == 128 - also an example parameter - you can use any other that corresponds to you filter length (number of coefficients). Also yo can try FIRMR (ippsFIRMRGetSize/Init and then ippsFIR) that supports explicit delay line - it will be easier for you to have stitched output signal.

regards, Igor

Reply