Re: Audio Unit valid Input and Output configuration
Re: Audio Unit valid Input and Output configuration
- Subject: Re: Audio Unit valid Input and Output configuration
- From: Bill Stewart <email@hidden>
- Date: Mon, 2 Jun 2003 23:11:33 -0700
Jeremy
On Monday, June 2, 2003, at 09:21 PM, Jeremy Sagan wrote:
I have been currently using the kAudioUnitProperty_SupportedNumChannels
call to determine the number of ins and outs of au's. But alas, this is
not the entire story but rather just the au's default input and output
channel scheme.
This is meant to be! the entire story - this is how the audio unit
reports its capabilities for the number of channels in and out... The
excpetion to this is that AU's of type 'aufx' and 'aumf' (Effect units)
- if they do not support this property are assumed to be able to deal
with N->N channels
So to enhance my product I decided to call through to
set the stream format manually with kAudioUnitProperty_StreamFormat.
This seems to work for au's that support the
kAudioUnitProperty_SupportedNumChannels call. Now if I get an error
from an au on this call, I should, according to the following note, be
able to select a channel configuration where ins = outs. However,
Apple's plug-ins namely, delay (and others) do not allow ins = 1, outs
= 1. To make matters worse this is not reported when the plug-in's
format is set but rather when it is asked to render its output.
This would be a bug - please let me know which units are behaving this
way... Is this just the delay (I'll check it!)
Bill
Please help me. I simply want to select the best input/output
configuration for all audio units depending on the context that the
user inserts the audio unit. In other words, if an au is inserted in a
mono track I would like the delay to either be 'mono in-mono out' or
'mono in-stereo out'.
Here is the comment, from
Developer/Documentation/CoreAudio/AudioUnits/index.html, that is
causing me confusion.
"/* If kAudioUnitProperty_SupportedNumChannels is not implemented, the
Audio Unit may be agnostic about
the number of channels and only a format setting can validate whether
the channels are accepted.
Generally, this will mean (particularly with Effect Units) that any
number of channels are usable as
long as there is the same number of channels on both the input and
output scopes. Other units can
accept a mismatch in the channelization of their busses, thus this
property is provide to allow those
units to publish the allowable channel configurations that can be
accepted on input and output.
*/
Again, this would be fine except the format setting does not return an
error.
Jeremy
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.
--
mailto:email@hidden
tel: +1 408 974 4056
________________________________________________________________________
__
"Much human ingenuity has gone into finding the ultimate Before.
The current state of knowledge can be summarized thus:
In the beginning, there was nothing, which exploded" - Terry Pratchett
________________________________________________________________________
__
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.