Re: [SoX-users] Mixing in a repeating track into a song

[robs <aq...@ya...>]

--- Wojciech Knapik <web...@wo...> wrote:
>    As for $rand1 - I experimented with the values you suggested and this 
> range seems a little too broad to me. I don't know, maybe it was the 
> sample I used, but it sounded a little ridiculous when i got to more 
> than +50, or less than -50.. Could sticking with such a small range 
> cause significant problems (as opposed to using -200:200) ?

I chose 200 as it's only one musical tone (i.e. the difference between a C note
and a D note),  but let me just give it a quick try...
Ha, ha, ha! Yes, it does sound a bit ridiculous!
50 should be fine providing you make sure you get a few figures after the
decimal point.

>    As for $rand2 and $rand3 - I read about the allpass effect in the sox 
> man page and the link provided there, but I honestly don't get any of it 
> ;] Any suggestions as to these ranges ?

What we're doing here is splatting some inaudible phase shifts into the audible
part of the signal so say freq between 1000 & 2000 Hz and bandwidth between 1 &
2 octaves should be sufficient.  Again, a bunch of figures after the decimal
point is needed for this to be effective against removal.

> > sox rand-lector.wav 5min-lector.wav pad 10 10 repeat 9
> > 
> > to get your 5 minute file with lector roughly every 30 secs, though it
> would be
> > much better to use a fresh rand-lector.wav for each repeat---see the
> soxexam
> > manual page for hints on how this can be scripted.
> 
>    I could just generate multiple rand-lector files and concatenate them 
> into one 5min-lector - is that what you meant ?

Basically, yes.  The pad effect places the lector in the middle of a 30 sec
window.  Of course, concatenation is easy with sox, but if you want to do it in
a loop it can be a little inefficient; the scripting example in soxexam shows
how to do concatenation in a loop in a slightly more efficient way, but it
might not be necessary in your case. 

> > Mixing will reduce the volume of the track, this can be constrained to just
> the
> > points during which the lector is active by using compand with sox -m.
> 
>    The compander proved to be no less esoteric, than the allpass filter 
> ;] I tried reading the wikipedia entries for both, but that didn't help 
> a lot, so once again any hints would be very much appreciated..

Might be more trouble than it's worth, but you could use something along the
following lines:
play -m input.au 5min-lector.au compand 0.2,.2 6:-70,-60,-20 -8 -90 0.1

> > I would recommend using a low bitrate for the demo songs (e.g. ogg level 1
> or
> > 2) just to keep your net bandwidth down.
> 
>    I was thinking of streaming mp3 and ogg in two qualities - 128 and 
> 192 for mp3 and as for ogg, I haven't really decided yet - I have little 
> experience with this format. These mp3 qualities are roughly equivalent 
>   to ogg level 3 and 4, aren't they ?

I believe so; guess you'll have to play this one by ear ;)

> > Please donate your SoX scripts back to the SoX project if you get them up
> and
> > running; they would make an interesting example for others to learn from.
> 
>    I'll share my scripts as soon as they're done. Should I send them to 
> this list ?

Yes that would be great.

Cheers,
Rob


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