Re: A modest proposal (regarding multi-I/O for AUs)
Re: A modest proposal (regarding multi-I/O for AUs)
- Subject: Re: A modest proposal (regarding multi-I/O for AUs)
- From: Olivier Tristan <email@hidden>
- Date: Thu, 18 Nov 2004 11:20:43 +0100
Stefan Gretscher wrote:
(A) AUs will typically support several but not all possible channel
counts on its busses, some will e.g. only do mono and stereo, others
will only do stero and 5.1 surround, etc.
There's also AUs like Reaktor that can do any channel count per bus up
to a certain limit. (Note that it's entirely possible with these AUs
to e.g. use a 3-channel format on a bus, for which there is no channel
layout etc. which causes problems with other areas of the specs, but
that's to be discussed later when we're going about solutions.)
(B) AUs may have equal capabilities across all busses, others may e.g.
do surround only on the first bus, while the other busses can only do
stereo or mono. An example here is RM IV which has a fixed amount of
stereo outs followed by a fixed amount of mono outs
(C) AUs may very likely be limited in the total number of channels
they can do across all busses.
(D1) It is also possible that there is a limit in the bus count that
an AU can handle, or that
(D2) the bus count is fixed.
(E) A bus might have a special function, like in the case of DLS
where the first bus can output the dry signal and the second bus the
reverb signal. (Using this in plain stereo only will result in a
different behaviour, everything will be on the first bus then.) Thus,
it is important for an AU to know whether a bus is going to be used by
the host.
These restrictions can come in pretty much any combination, which is
why I listed them this way instead of trying to categorize the AUs
into groups.
Looking at this list (which may not even be complete yet, please add
what you feel is missing), I think it's pretty obvious that a solution
that allows for expressing all these restrictions will not be as easy,
and it perfectly explains why the CoreAudio team ended up with a spec
that many think is overly complex - it's in the nature of the problem.
I don't know if it can be made any easier, but my main gripe with the
current standard is that it doesn't even cover all of the above. For
instance, there's no reasonable way for expressing this requirement:
consider a sampler that is able to do
(A) mono, stereo and 5.1 surround,
(B) does offer these formats equally on all busses
(C) can do a maximum of 32 channels
(D) doesn't care about the bus count as long as (C) is ok
(E) treats all busses the same
This is basically a standard sampler, nothing fancy, but it can't be
expressed in the current specs.
Looking forward to your input on this,
Stefan
Hi Guys,
Maybe a system like Protools AOS could be an idea to follow.
Each Plug gives output format wich is supported for the main output
(mono, stereo, quad, 5:1).
When you create an instrument, the host can ask for the format of the
main output betwwen all the supported format.
Then the plug can add extra outputs wich special format : four mono
output, two stereo outputs and five 5:1 outputs.
Those extra outputs can be connected on audio tracks as input at runtime.
There is also a cool feature on their system, because if an output is
not use then it s not displayed. (It avoid problems like in Cubase,
where is the plug have 32 outputs, all are displayed even if there are
not used.) and the output buffer do not need to be feeded, so if you
only use two ouputs then no extra cost is needed.
My 2 cents,
--
Olivier Tristan
Ultimate Sound Bank
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden