[CM] Snd-8(.5) questions (newbie)

[Bill Schottstaedt]

> 1a. How can I get the "mean/average" value of all samples? 

(let ((sum 0.0)) 
  (scan-channel (lambda (y) (set! sum (+ sum y)) #f)) 
  (/ sum (frames)))


> 1b. How can I get the "mean/average" value of "selected" samples? 

(let ((sum 0.0)) 
  (scan-channel (lambda (y) (set! sum (+ sum y)) #f) 
                (selection-position) (selection-frames)) 
  (/ sum (selection-frames)))


> 2a. How can I get the "mean/average" value of the "amplitude" for all 
>   samples? 

There's no distinction between a sample and its amplitude.


> 3a. How can I get the "RMS" value for all samples? 
> 3b. How can I get the "RMS" value for "selected" samples? 

similar to above but return RMS.


> 4a. How can I get the "standard deviation" value for all samples? 
> 4b. How can I get the "standard deviation" value for "selected" samples? 

similar to above, but return standard deviation.


> 5a. How can I get the "min" and "max" values of all samples? 
> 5b. How can I get the "min" and "max" values of "selected" samples? 

maxamp and selection-maxamp


> (In case of 5.a and 5.b also getting the "sample number" would be nice, or 
> maybe one could afterwards "search" for samples of a given "value" using 
> the "find-channel" function, for example?) 

maxamp-position and selection-maxamp-position


> 6.a How can I "add/subtract" a value to/from all samples? 
>    (I believe I have found the answer to 6.a ... "offset-channel".) 
> 6.b How can I "add/subtract" a value to/from "selected" samples? 

(map-channel (lambda (y) (- y .1))) ; or whatever you want to subtract


> From these four "independent" mono tracks, I would like to produce a 
> "stereo" file (2 channels). 

see mono->stereo in extensions.scm


> In "professional live" recordings, you can 
> actually "hear" that one guy is staying left to you, another one right to 
> you, and so on ... and this is exactly what I would like to achieve, too. 
> I would like to "hear" the Soprano most left, Alto left-middle, Tenor 
> right-middle, Bass most right ... 

perhaps place-sound is what you want.