= Format of filter files =
The filter files are line oriented, that means there is one information entry per line. Blank lines are not allowed! The format of the filter files is as follows:
== FFT filter ==
* All lines at the beginning of the file starting with exclamation sign ! are comments and ignored by the program.
* The first data line is a magic number and must be 1357913578
* The next data line contains the number 1, which is an ID for FFT filters.
* Normalization value (real number), which is multiplied to the output samples of the filter.
* Number of zeros z (integer)
* z lines following with one zero each in the format (,). Both parts of a complex conjugate pair must be specified.
* Number of poles p
* p lines following with one pole each in the same format as zeros.
[http://www.seismic-handler.org/portal/browser/SH_SHM/trunk/filter/GRFO_S%2BSRO_LP.FLF Example of an FFT filter file].
== Recursive filters ==
* All lines at the beginning of the file starting with exclamation sign ! are comments and ignored by the program.
* The first data line is a magic number and must be 1357913578.
* The next data line contains the number 3, which is an ID for recursive filters.
* Sample rate for which this file is valid (real number)
* Normalization value (real number), which is multiplied to the output samples of the filter.
* Number of numerator coefficients n (integer)
* n lines following, one coefficient (real number) in each.
* Number of denominator coefficients d (integer)
* d lines following, one coefficient per line.
* Optional following other stages of the filter, new stage indicated by a line containing a single @.
* Additional stages are repeating the entries 'ID number 3' until denominator coefficients.
[http://www.seismic-handler.org/portal/browser/SH_SHM/trunk/filter/20HZ_GRSN_S%2BSRO_LP.FLR Example of a recursive filter file].
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