Re: efficient device channel enabling - was Re: fIsMixable
Re: efficient device channel enabling - was Re: fIsMixable
- Subject: Re: efficient device channel enabling - was Re: fIsMixable
- From: Doug Wyatt <email@hidden>
- Date: Tue, 3 Feb 2004 08:35:46 -0800
On Feb 2, 2004, at 19:35, Kurt Bigler wrote:
Reviving an old topic...
on 6/18/03 12:02 PM, Jeff Moore <email@hidden> wrote:
To date, there haven't been too many apps that have taken advantage of
the ability to enable and disable streams. I'm not entirely sure why
that is, but at least part of that is our fault. We have not fully
implemented that support in the HAL Audio Units or in the Sound
Manager. This will be fixed as time progresses.
I am about to revisit the issue of implementing stream enables in my
application. How has support for stream enables changed since you
posted
the above reply last year?
Do I have to abandon audio output units and use the HAL directly in
order to
use stream enables? Or do I just add some HAL calls to do the stream
eanbling and trust that audio output units will behave intelligently in
relation to devices that have had some streams disabled via the HAL
API?
The audio (input/)output units present all of a device's streams as a
single bus with N channels (where N is the sum of the number of
channels in each stream). You set an *input* format to the output unit
(set on element 0 in the input scope), and you can map your input
channels to the hardware channels using the output unit's channel map
property. The output units will then dynamically enable/disable the
hardware streams according to which ones are being addressed.
This is as of Panther / QT 6.4.
Doug
--
Doug Wyatt
Core Audio, Apple
_______________________________________________
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.