Re: Datasources and digital audio output
Re: Datasources and digital audio output
- Subject: Re: Datasources and digital audio output
- From: Derk-Jan Hartman <email@hidden>
- Date: Sun, 13 Nov 2005 01:11:55 +0100
On 11-nov-2005, at 20:55, Jeff Moore wrote:
On Nov 11, 2005, at 10:50 AM, Derk-Jan Hartman wrote:
I have a G5 now, so i can finally start work on supporting the
digital out of the G5.
Can anyone explain the concept of "Datasources" for output devices?
I tried looking in the documentation, but couldn't find anything
useful.
The data source control of an output provides a means of telling
the hardware which destination, from a set of mutually exclusive
choices (analog and digital in the G5 case), to send the data. I'm
not sure how to explain it more simply than that.
So I should consider it as a "hint" to the driver about the
destination output port of the audio? There is no implied meaning at
the application level?
On the G5, the 2 datasources are presented to the users as two
different devices in the Sound PrefPane.
Yes, but the Sound Prefs pane is presenting a greatly simplified
view of the devices on the system. It's example should not, in
general, be followed by applications that are implementing their
own device selection UI.
Right ok... But how else am I gonna know in my application if the
user wants to make use of his digital output port?
I mean selecting cac3 when you only have plain "Line Out" , makes no
sense, and will cause that you have no audible output at all. Be it
stereo or encoded digital.
Selecting one of them changes absolutely 0 to the setup of the
device from what I can see.
Incorrect. It has changed the value of the data source selector and
has redirected the audio output to the chosen port. I think some of
our built-in hardware knows whether or not something is actually
plugged into the optical jack, so it may still get sent to the
analog output when there isn't anything plugged in. I forget and I
don't have a G5 in front of me to check.
I believe the G5 is one of those.
I both modes all the lpcm and cac3 streamformats are available. So
should I see this as some sort of "preference" ??? What are these
"datasources" an abstraction of?
You are making connections where none are implied. The data source
and the available formats don't necessarily have anything to do
with each other.
So if there is no connection, then I am unable to automate the
selection of the digital format from an application? My only option
is providing an application specific preference that says: "Output
encoded audio", and have the user select this if he wants to use it?
I had anticipated that a user could select this systemwide in one
form or another, but apparently that's not the case.
I think i'll take the approach of listing the device twice, in case
it provides the cac3 format.
DJ
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden