Re: Channels and frames
Re: Channels and frames
- Subject: Re: Channels and frames
- From: William Stewart <email@hidden>
- Date: Thu, 3 Nov 2005 10:48:56 -0800
Here are your choices:
* { {2, 2} {1, 1} }
What this means is that regardless of your number of buses, the AU
can be configured to have 2 input channels and 2 output channels (or
1 input channel, and 1 output channel). You cannot have mixed channel
counts on input or output buses.
* { {2, 2} {1, 1}, {1, 2} }
That is, you want to allow mono or stereo inputs and stereo outputs,
and for a mono output only mono inputs are legal.
(And for completeness)
* { {2, 2} {1, 1}, {2, 1} }
That is, you want to allow mono or stereo inputs and mono output, and
for a stereo output only stereo inputs are legal.
* { {2, 2} {1, 1}, {2, 1}, {1, 2}}
Any combination of mono or stereo inputs or outputs are allowed.
The approach we take to this is that if the AU is going to deal with
uneven channel counts (mono input and stereo output), then it has to
be prepared to deal with the full ramifications of that feature.
We've looked at ways to somehow publish more restricted lists, but
don't like the complexities this involves.
You can use AU Lab => /Developer/Applications/Audio to test this - is
has support for input and output side chains. CAAudioUnit (in
PublicUtility in the SDK) has code to validate channel
configurations if you want to look at how the host deals with these.
auval will correctly validate these configs.
Bill
On 03/11/2005, at 7:36 AM, john smith wrote:
Hi,
Please disregard my previous question about the output bus. I think
I understand it now.
But... (and someones gonna kill me for asking.)...
an additional "sidechain" input for AU effects is described as a
separate bus - so in your case the AU must specify that it can
handle mono and stereo inputs and outputs (config list: [1,1],
[2,2]) and it must provide two input busses and one output bus.
How can I inform the host about the channel count on the second bus?
And how can I make sure that it only connect with 1 channel on the
second bus when running in mono mode, and with 2 channels on the
second bus when running in stereo mode?
(i.e. avoid mono sidechains when running in stereo and vice versa).
Thanks,
Michael Olsen
Best,
Stefan
Am 03.11.2005 um 12:35 schrieb john smith:
I'm about to create a channel strip product for a client.
Besides the "usual" channel configurations (1->1, 1->2, 2->2) it
has some alternative configurations, namely 2->1 and 4->2. The
thing about those configurations is that they have extra side-
chain inputs.
For instance, the one I call 2-> has 1 audio in, 1 side-chain in
(which is of course also audio, but I'm sure you're catching my
drift), and 1 audio out.
My question is: If I tell the host (Logic or otherwise) that I
can accept 2 channels in and 1 channel out, will the host know
what the second input is a side-chain input?
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