[SoX-users] pipe -limit of arguments?

[Schumacher M. <mar...@mu...>]

Hello list,

I experimented a bit with the fir effect piped as an input to another sox command (MacOS, sox14.3.2). 
There seems to be a limit in terms of number of arguments (coefficients) that can be sent through the pipe.

I did some tests convolving white noise (soundfile) with a 441 point sinc-function (a 'rectangular' lowpass in the frequency domain), providing the coefficients (time-domain sample-values of the sinc function) directly to the command-line, e.g.

sox infile.aif outfile.aif fir <list-of-coefficients>

-Works fine as expected. However, when using this sox command as an input pipe to another sox command: 

sox "|sox infile.aif -p fir <list-of-coefficients>" outfile.aif 

-the result looks more like white noise convolved with a damped sinusoid (which made me suspect that a substantial part of the sinc-function must have been truncated). When providing the coefficients as a textfile to fir this does not happen (i.e. the result is correct):

sox "|sox infile.aif -p fir mycoefficients.txt" outfile.aif 

Truncating the list of coefficients in the textfile to (the last!) 53 coefficients yields the same result as providing the coefficients as a list through pipe.
Is this known? Could someone confirm perhaps?


Thanks,
Marlon