Subject: Re: [alsa-devel] Re: [linux-audio-dev] laaga, round 2
From: Karl MacMillan (karlmac_AT_peabody.jhu.edu)
Date: Thu May 10 2001 - 06:20:06 EEST
On Wed, 9 May 2001, Paul Davis wrote:
> >I'm guessing that you won't be happy with applications `reserving'
> >hard-coded channel numbers. I mean I could write my application to
> >always output to channels 110-113. That would be handy for me the
> >coder and me the user because I can easily remember these numbers.
> >This is a bit like TCP/IP port numbers being hard-coded for particalar
> >servers. Do we want this situation ? I'm guessing that you as a
> >server-writer wouldn't be so happy with this approach.
>
> You seem to think that plugins "reserve" channels in some kind of
> exclusive sense. Thats not true.
>
> We don't care how many plugins are using any channels (well, we need
> to know, but we don't care ;) We don't care which plugins use which
> channels. A single channel is an essentially infinite resource: as
> many plugins can use it as you can imagine.
>
Perhaps I am missing something, but it is not clear in what order the
plugins will read and write to the channels. For example, to record a
softsynth the softsynth must first write to the channel and then the
recording plugin would read that data. This may be easy because there is
only one reader and one writer, but then add, say, an few effects box apps
(I don't mean LADSPA plugins here - I mean whole apps that do signal
processing). In what order do they access the channels? The order that
they are loaded? This, to use the mixer concept you seem to be going for,
is like the effects sends order being determined by when you patch in
something thru the patchbay!
It seems much easier to remove the whole concept of physical channels and
let the plugins simply request the number of channels that they want. The
bus id would simply be a handle that doesn't necessarily refer to
anything. That way each server could handle the connections however they
want - it could even use the entirely passive model. Of course, what is
left is basically LADSPA without the control ports. In fact, it strikes
me that LAAGA could be scraped and a LADSPA host could be written that
would handle everything that has been proposed here!
Karl
_____________________________________________________
| Karl W. MacMillan |
| Computer Music Department |
| Peabody Institute of the Johns Hopkins University |
| karlmac_AT_peabody.jhu.edu |
| www.peabody.jhu.edu/~karlmac |
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