Re: Surround info please
Re: Surround info please
- Subject: Re: Surround info please
- From: William Stewart <email@hidden>
- Date: Thu, 22 Jun 2006 10:17:55 -0700
On 22/06/2006, at 9:55 AM, Dave Hoskins wrote:
Hmm, O.K. thanks for the pointers Bill. Auval is showing that I
needed to fix some things. I've noticed that Apple's AUReverb shows
a list of named channel configs like 'Mono/Stereo' etc, I guess it
gets these from the each element layout, but how do I code that
specifcally? I've looked through a dozen projects on the net, and
none of them go near this area.
The channel layouts are handled on the IOElements - have a look in
AUScopeElement in the AUPublic dir... The idea is you subclass this
and provide your own element type. The element type is where the
format for input or output is kept too.
Also I find it a little confusing that it appears to set up only 2
stereo in and outs at the begining of the output of auval for
Apples plugs even though they later say the can have 5. And it's a
little weird that Apples reverb doesn't show in DP's 5.1 busses,
but their pitch shift plugin does - it has a '(5.1)' next to it's
name.
We don't generally provide support for .1 channels in our AUs. The
LFE is normally handled differently (as sometimes the centre channel
is as well) - so our AUs support 5.0 for example. If the bus is 5.1
(that is, 6 channels), then it probably has a mismatch in the channel
counts.
Bill
A more literal help would be great, some source code would be
fantastic! Unfortunately, flying half way around the world to a
conference is not practical for me at the moment. Can anyone help
please, I really need to get on with coding the actual DSP bits! ; )
Cheers,
Dave Hoskins
www.quikquak.com
On 20/06/2006, at 6:41 AM, Dave Hoskins wrote:
Hello all, I've been looking through this list for channel
layout usage and examples. But all I've found is a couple of
hints, and people saying there's examples in source code that I
can't find, like the matrix reverb stuff.
Yes - if you run this AU in auval you'll see it has surround
capabilities - and auval is testing the different configs, and the
channel layouts that it reports.
I've created a reverb plug-in that can switch between 2/4/5
channels.
ok - so make sure that as the client changes your format to
ensure that the ACL reflects the number of channels. We expect
that the AU's ACL always reflects the number of channels of a bus
correctly - and the AU itself has to play some role in
maintaining this consistency (and checking it as well). How a
format is set doesn't change of course - the ACL just provides
meta information about a format - the role of each channel.
I've got as far as setting the number of channels, but functions
like 'CreateElements' don't even show in the API references.
Because they aren't an API - its a part of the AU SDK and all the
source is there. There's also some reference documents in /
Developer/ Examples/CoreAudio/Documentation
And looking for anything using SetAudioChannelLayout turns up blank!
auval will do this
We're also going to be covering surround AU topics at this year's
WWDC in some depth - if you can come to the conference I think
you'll find the session useful (and we'll also be running a lab
for more focussed Q & A time with developers)
Bill
Can anyone help please? I'll need a little more than 'just over-
ride some functions' answers thanks. : )
Again I don't know why there are no examples of multi-channel
audio units.
Thanks in advance,
Cheers, Dave Hoskins
www.quikquak.com
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