Re: mic or line input selection?
Re: mic or line input selection?
- Subject: Re: mic or line input selection?
- From: Mark Cookson <email@hidden>
- Date: Fri, 6 Sep 2002 10:50:25 -0700
On Friday, September 6, 2002, at 10:16 AM, Michael Thornburgh wrote:
as a followup to Mark's comments about system-wide vs
per-application input sources: the device itself can
have only one input source (per stream) selected at
once. you can't have one application on your tibook
recording from built-in audio's built-in microphone,
with another simultaneously recording from built-in audio's
line-in jack. think of the sources as different terminals
that can be switched onto the actual audio processing
path(s) (the stream(s)).
Yes, this is true. This is how the built in hardware works. For most
sound chips, we only have one A/D or D/A so that if there are multiple
sources, they are all exclusive (though some might be on a mixer, but
we treat mixers as selectors, so it doesn't really affect this
discussion).
One sound chip has multiple A/D D/A converters, but for simplicity (and
trust me, this chip needs to be simplified :-) ) we treat it as if
there was only one D/A and A/D. We stopped making/using that chip
about 5 years ago, so there isn't much of a chance that we'll ever
update the driver to have multiple streams to allow multiple
applications to record from its multiple inputs. Sorry.
--
Mark Cookson
Engineering Droid
Apple Computer, Inc.
Core Audio CPU Software
6 Infinite Loop MS 306-2CW
Cupertino, CA 95014
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