Re: Sox FM Radio Processing Example

["Måns Rullgård" <mans@mansr.com>]

<alant123@btconnect.com> writes:

> Hi all.  
>
> I have used Sox for simple stuff in the past but am intrigued by the FM
> Radio processing example which (in different variations over time) appears
> in the man page.  It may be just what I am looking for - but I can't get it
> to work.  Referring to various posts on the Internet asking about this and
> also different versions of the man page scattered around, I have gleaned
> that the sinc effect is now the filter effect? However, there is still
> something wrong I get an error.  Oddly, the sox manpage for Ubuntu 18 still
> uses the "sinc" version. 

It's the other way around, sinc is the new name (since 2009).

> I am using it in a script file that contains this:
>
> play t1.wav gain -3 filter 8000- 32 100 mcompand \
>                    "0.005,0.1 -47,-40,-34,-34,-17,-33" 100 \
>                    "0.003,0.05 -47,-40,-34,-34,-17,-33" 400 \
>                    "0.000625,0.0125 -47,-40,-34,-34,-15,-33" 1600 \
>                    "0.0001,0.025 -47,-40,-34,-34,-31,-31,-0,-30" 6400 \
>                    "0,0.025 -38,-31,-28,-28,-0,-25" \
>                    gain 15 highpass 22 highpass 22 filter -17500 256  \
>                    gain 9 lowpass -1 17801
>
> but I get the following error message
>
> "play FAIL gain: usage [-e] [-b] .."

That's because "filter" isn't a valid effect name, to it's parsed as an
argument to the "gail" effect which (rightly) rejects it.

> For reference this is copied from the manpage at 
>
> https://linux.die.net/man/1/sox

That's a very old version of the man page.  Unfortunately, the current
one is also wrong.  Someone simply forgot to update that example at some
point.  I've fixed it just now.

Here's the updated command:

    play track1.wav gain -3 sinc -n 29 -b 100 8000 mcompand \
      "0.005,0.1 -47,-40,-34,-34,-17,-33" 100 \
      "0.003,0.05 -47,-40,-34,-34,-17,-33" 400 \
      "0.000625,0.0125 -47,-40,-34,-34,-15,-33" 1600 \
      "0.0001,0.025 -47,-40,-34,-34,-31,-31,-0,-30" 6400 \
      "0,0.025 -38,-31,-28,-28,-0,-25" \
      gain 15 highpass 22 highpass 22 sinc -n 255 -b 16 -17500 \
      gain 9 lowpass -1 17801

Hope this helps.

-- 
Måns Rullgård


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