RTF_CREATE_DOWNSAMPLER(3)					 rtfilter library					 RTF_CREATE_DOWNSAMPLER(3)

NAME

       rtf_create_downsampler - Creates downsampling filter

SYNOPSIS

       #include <rtfilter.h>

       hfilter rtf_create_downsampler(unsigned int nch, int type,
				      unsigned int r);

DESCRIPTION

       rtf_create_downsampler()  creates  a  filter that downsamples signals coming from nch channels of type type (see rtf_create_filter(3)) by a
       decimation factor of r (i.e. the sampling frequency of the input will be r times the sampling frequency of the output).	This  is  achieved
       internally by applying a lowpass 4-order Chebychev filter to the input data using a normalized cutoff frequency of 0.8/(2*r) and decimating
       the result every r samples.

RETURN VALUE

       Returns the handle to the created filter in case of success, NULL otherwise.

NOTES

       On the contrary of most other filters, the number of samples returned by rtf_filter(3) is different than the input (as expected)  but  also
       may vary at each call if the number of sample supplied in input is not a multiple of r.

SEE ALSO

       rtf_filter(3), rtf_create_filter(3), rtf_destroy_filter(3)

EPFL
								       2010						 RTF_CREATE_DOWNSAMPLER(3)