Re: 'Ganged' or 'Linked' Hardware
Re: 'Ganged' or 'Linked' Hardware
- Subject: Re: 'Ganged' or 'Linked' Hardware
- From: Jeff Moore <email@hidden>
- Date: Fri, 18 Apr 2003 12:31:01 -0700
A property to indicate hardware synchronized devices is not a bad idea.
Some devices could also go a step further, and make the multiple
instances of the device appear as a single device with that many more
streams. Of course, only devices that truly function as one could do
that. That's why a property is also a good idea.
As for the Sound Manager and other apps using the stream enable/disable
stuff, some of that went into 10.2.5, but some of it is still yet to
come.
On Friday, April 18, 2003, at 10:42 AM, B.J. Buchalter wrote:
on 4/18/03 1:10 PM, Matthew Xavier Mora at email@hidden wrote:
Maybe CoreAudio can add a property for kexts to publish which is a
"linkable" property. This property could contain either a class name,
or a list of GUID's that this device can link to. So when multiple
Mobile I/O's are plugged in, each instance can publish this property.
In Audio midi setup the user can then link or unlink them with the
direction of the link establishing master/slave relationship. It
could be a read only property describing to the user the link setup
if the driver has its own set up app. Also you could link the input
of one device to the output of other devices so that they could run
in sync.
The fact that this would be a standard property (instead of each
driver coming up with its own way to do it) would mean that the pref
would be saved and restored automatically by the system. The issue is
that kext don't really have an easy way to save off preferences so
it's nice to get help from CoreAudio.
Right. I guess that if there is no standard property for this, it could
still be implemented as a HAL plug-in for the property. But then AMS
would
not show it, so it would still only be supported by a vendor provided
control app. The lack of persistent preferences for kexts is
definitely one
big issue in all of this.
The second big issue is that (unless I am missing something) the
current
implementation of the HAL and Sound Manager are not taking advantage
of the
stream enable properties in the HAL. Currently we have a big enough
problem
with 18in/18out devices chewing up the CPU when playing iTunes since
iTunes
(presumably through the sound manager) is actually running all the
streams
in both directions just to play stereo. If we start healing devices,
then we
could presumably see linked devices that publish 60-100 streams or
channels
in both directions. To use one of these devices to play a stereo
output will
be crazy. We really need to have ALL CA clients use the stream enables
(both
Sound Manager based and HAL based), and we need CA to respect them.
Otherwise, big I/O devices appear to the user to be really inefficient.
Best regards,
B.J. Buchalter
Metric Halo
M/S 601 - Building 8
Castle Point Campus
Castle Point, NY 12511-0601 USA
tel +1 845 831-8600
fax +1 603 250-2451
If you haven't heard ChannelStrip yet, you don't know what you're
missing!
Check out SpectraFoo, ChannelStrip and Mobile I/O at
http://www.mhlabs.com/
Download a 12 day demo from <http://www.mhlabs.com/demo/>
--
Jeff Moore
Core Audio
Apple
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