Re: [SoX-users] Filter slopes and characteristics

[Klaus S. <kls...@go...>]

Hi Rob.

Are you working with double precision ? Would be great.


Cheers
Klaus

On Fri, Feb 6, 2009 at 6:58 PM, robs <aq...@ya...> wrote:

> --- On Fri, 6/2/09, Klaus Schulz <kls...@go...> wrote:
> > Are there any limitations related to music-data-formats,
> > fir-parameter-formats or filter taps?
>
> The limitations are: they only do what they say they do ;-)
>
> Here are the man page entries:
>
> fir [coefs-file|coefs]
>       Use SoX's FFT convolution engine with given  FIR  filter
>       coefficients.   If  a single argument is given then this
>       is treated as the name of a file containing  the  filter
>       coefficients  (white-space  separated;  may  contain '#'
>       comments).  If the given filename is '-', or if no argu‐
>       ment  is  given, then the coefficients are read from the
>       'standard input' (stdin); otherwise, coefficients may be
>       given on the command line.  Examples:
>
>         sox infile outfile fir 0.0195 -0.082 0.234 0.891 -0.145
>
>         sox infile outfile fir coefs.txt
>
>       with coefs.txt containing
>
>         # HP filter
>         # freq=10000
>           1.2311233052619888e-01
>          -4.4777096106211783e-01
>           5.1031563346705155e-01
>          -6.6502926320995331e-02
>         ...
>
> sinc  [-a  att|-b  beta]  [-p  phase|-M|-I|-L] [-t tbw|-n taps]
> [freqHP][-freqLP [-t tbw|-n taps]]
>       Apply  a sinc kaiser-windowed low-pass, high-pass, band-
>       pass, or band-reject filter to the signal.   The  freqHP
>       and  freqLP  parameters  give the frequencies of the 6dB
>       points of a high-pass and low-pass filter  that  may  be
>       invoked  individually,  or together.  If both are given,
>       then freqHP < freqLP creates a band-pass filter,  freqHP
>       > freqLP creates a band-reject filter.
>
>       The  default stop-band attenuation of 120dB can be over‐
>       ridden with -a; alternatively, the kaiser-window  'beta'
>       parameter can be given directly with -b.
>
>       The  default  transition  band-width  of 5% of the total
>       band can be overridden with -t; alternatively, the  num‐
>       ber of filter taps can be given directly with -n.
>
>       If  both  freqHP  and  freqLP are given, then a -t or -n
>       option given to the left of the frequencies  applies  to
>       both  frequencies;  one  of  these  options given to the
>       right of the frequencies applies only to freqLP.
>
>       The -p, -M, -I, and  -L  options  control  the  filter's
>       phase response; see the rate effect for details.
>
>       This effect supports the --plot global option.
>
> The `fir' coef data format is basically just space separated numbers in the
> range [-1, 1].  If your coefs are e.g. comma separated, you can use sed or
> tr to strip the commas.
>
> > What is your suggestion. Should I generate a mutichannel
> > .wav or three
> > separate .wav files
>
> Whatever seems easiest for your application I'd say; SoX does not have the
> ability to apply different effects-chains to different channels in a single
> invocation, so that may have some influence on this.
>
> Cheers,
> Rob
>
>
>
>