[Audacity-devel] Re: RingBuffer class

[Dave F. <dav...@co...>]

=46rom an unrelated discussion:

On Thursday 22 January 2004 07:22 am, you wrote:
> > I'm seriously hoping to be able to bring this code back into Audacity,
> > since I've been studying audacity code as a reference to this stuff.  :)
> >  I love open source.  ;)  At least I'll be able to use what I learned to
> > add multi-track output to audacity, if someone doesn't beat me to it.
>
> Good luck.  One thing to be thinking about re: multi-track output is
> how the UI should work.  Feel free to sketch some ideas - that's the
> part I'm the most unsure about.

Actually, I've been thinking about this a lot.  For starters, I've been=20
thinking about 4 or 6 track output, which would be dolby surround sound.  I=
=20
forget if dolby specifically calls for 4 or 6 tracks, just that I've seen i=
t=20
in some wav specification I read recently.

Anyway, to handle a fader control, obviously there would be another slider =
per=20
track for that.  I was thinking about something more positional, though, li=
ke=20
a box, and you click a point in the box that should have the most volume, a=
nd=20
then audacity (probably in audioIO) would calculate the correct volumes for=
=20
whatever amount of tracks you're using (4 or 6, based on a dolby or other=20
spec).  In any case, I figure a notebook control with two pages would work,=
=20
or a control that lets you switch between the two pages but not necessarily=
=20
by a tab widget.  One page is the two sliders and the other page is the box=
=2E =20
So if you're not doing surround sound, or you just prefer sliders over boxe=
s,=20
you would use that page.

The other solution, which is to handle multi-track sound cards specifically=
,=20
is more complex.  :(  I'm thinking that supporting this sort of output in t=
he=20
UI would be better done after the effects chains that have been previously=
=20
discussed have been worked out.  Then it'd just be a matter of making an=20
"effect" that outputs to a specific track on the soundcard and attaching it=
=20
to the end of the chain.  Or associating an optional output track in the sa=
me=20
dialog in which you assign an effect chain to a track or selection, and usi=
ng=20
cascading rules to determine where specific sections of tracks play.  I=20
haven't been able to come up with a simpler conceptual UI for this, except =
to=20
make another item in the track menu.  THis item would be a submenu and woul=
d=20
expand for the number of available tracks.  Then a button on the toolbar to=
=20
switch between stereo output (or surround output) and multi-track output=20
would determine whether audacity would use the pan and fader settings or th=
e=20
settings in this submenu.  None of this takes into account whether or not a=
=20
user wants to associate existing tracks with both input and output tracks,=
=20
which is behavior that would be useful to have since it's consistent with=20
existing analog and digital recorder devices, but doesn't make as much sens=
e=20
on a computer.  :)

When it's all said and done, you need two systems to handle multi-track=20
output.  You need a system for regular playback that supports surround-soun=
d=20
and you need a system for what I call studio playback, where you would use=
=20
the 8 or 16 track outputs that are available (or whatever, it's an arbitrar=
y=20
number).  The regular playback system is also the mix-down system and must =
be=20
supported when you export the file, provided the target format supports=20
surround sound.  OPen for debate whether or not audacity should be able to=
=20
export an arbitrary number of tracks into an interleaved wav file.  :)

Anyway, since you mentioned it I thought I'd just throw down my thoughts on=
=20
the matter as they stand.  Obviously nobody's working on it, yet, but I=20
recall it being requested for 1.4, so now's as good a time as any to throw=
=20
out my thoughts.

Dave

=2D-=20
Mediocrity finds safety in standardization.
		-- Frederick Crane