Re: [Audacity-nyquist] extreme newbie question about abs function

[Jeff R. <jef...@ya...>]

All: this plugin does exactly what I was trying to do. Thank you.

The workaround was a lot more involved than I would have guessed!

--- David Sky <dav...@vc...> wrote:
> Thanks Steven, s-max does work, but only on mono signals, even if
> I include a (if (arrayp s)...) check, as below (which I have
> commented out). Below that is the Nyquist error msg, which I don't
> understand. David
> 
> ;nyquist plug-in
> ;version 1
> ;type process
> ;name "Rectifier..."
> ;action "Rectifying audio..."
> ;info "Code by Steven Jones\nReleased under terms of GPL"
> 
> ;control rectify "Rectify" int "0=half 1=full" 1 0 1
> 
> ; Rectifier compiled by David R. Sky,
> ; code by Steven Jones
> ; March 29, 2005
> ; Released under terms of the GNU Public License
> ; http://www.opensource.org/licenses/gpl-license.php
> 
> ; Return only the positive half cycles of signal
> (defun pos (signal)
> (s-max signal 0))
> 
> ; Return only the negative half-cycles of signal
> ; AND invert them.
> (defun neg (signal)
> (pos (scale -1 signal)))
> 
> (defun my-abs (signal rectify)
> (if (= rectify 1)
>     (sum (pos s) (neg s))
> (pos s)))
> 
> ; checking for stereo signal
> ; (if (arrayp s)
> ; (vector (my-abs (aref s 0) rectify)
> ; (my-abs (aref s 1) rectify))
> (my-abs s rectify)
> ; )
> 
> error: bad argument type - 0
> Function: #<Subr-LENGTH: #12cbb40>
> Arguments:
>   0
> Function: #<FSubr-COND: #12cb570>
> Arguments:
>   ((/= N (LENGTH S2)) (ERROR "unequal number of channels in max"))
> Function: #<FSubr-LET*: #12cb430>
> Arguments:
>   ((N (LENGTH S1)) (P (MAKE-ARRAY N)))
>   (COND ((/= N (LENGTH S2)) (ERROR "unequal number of channels in
> max")))   (DOTIMES (I N) (SETF (AREF P I) (S-MAX (AREF S1 I) (AREF
> S2 I))))   P
> Function: #<Closure-NYQ:MAX-OF-ARRAYS: #12fe068>
> Arguments:
>   #(#<Sound: #7cb2390> #<Sound: #7cb2618>)
>   0
> Function: #<FSubr-COND: #12cb570>
> Arguments:
>   ((ARRAYP S1) (NYQ:MAX-OF-ARRAYS S1 S2))
>   (T (NYQ:MAX-2-SOUNDS S1 S2))
> Function: #<Closure-S-MAX: #12fe548>
> Arguments:
>   #(#<Sound: #7cb2390> #<Sound: #7cb2618>)
>   0
> Function: #<Closure-POS: #130be80>
> Arguments:
>   #(#<Sound: #7cb2390> #<Sound: #7cb2618>)
> Function: #<FSubr-IF: #12cb3f0>
> Arguments:
>   (= RECTIFY 1)
>   (SUM (POS S) (NEG S))
>   (POS S)
> Function: #<Closure-MY-ABS: #130bb00>
> Arguments:
>   #(#<Sound: #7cb2390> #<Sound: #7cb2618>)
>   1
> 1> [ gc: total 18640, 3629 free; samples 1KB, 0KB free ]
> 
> 
> 
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