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Re: Getting Default Output Device gives a strange answer
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Re: Getting Default Output Device gives a strange answer


  • Subject: Re: Getting Default Output Device gives a strange answer
  • From: Jeff Moore <email@hidden>
  • Date: Tue, 14 Nov 2006 14:30:11 -0800

It can't hurt to install an atexit handler, but it may not be reliable as the HAL also installs one to clean itself up. The order of execution of atexit handlers doesn't appear to be specified according to the man page. So, if the HAL's handler executes first, you won't be able to call back into the HAL from your handler.

On Nov 14, 2006, at 1:18 PM, Andrew Kimpton wrote:

Quoting Jeff Moore <email@hidden>:

In order for a device to be allowed to be the default device, it has to
meet the following criteria:
1) It has to allow itself to be the default device.
2) It can't be hogged.
3) It has to have at least one mixable linear PCM stream in the given
direction whose terminal type is general purpose (includes streams that
don't provide a terminal type).


Chances are that your experiments with AC-3 have left the device in a
state such that it can't satisfy the third criterium. Rebooting won't
help, as the HAL will be happy to restore the device's format to AC-3
(I had a bug to keep this from happening that may be fixed in Tiger,
though). The thing to do to fix this state is to open AMS and manually
select a linear PCM format.

OK - I'll give that a try when I get home (at work - no where near the problem machine - right now).


In order to avoid this sort of thing should I make sure to install some sort of 'atexit' handler to release hog mode before the app quits ? That won't protect against crashes but would at least protect against impatient 'ctrl-c' usage.


--

Jeff Moore
Core Audio
Apple


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References: 
 >Getting Default Output Device gives a strange answer (From: Andrew Kimpton <email@hidden>)
 >Re: Getting Default Output Device gives a strange answer (From: Jeff Moore <email@hidden>)
 >Re: Getting Default Output Device gives a strange answer (From: Andrew Kimpton <email@hidden>)
 >Re: Getting Default Output Device gives a strange answer (From: Jeff Moore <email@hidden>)
 >Re: Getting Default Output Device gives a strange answer (From: Andrew Kimpton <email@hidden>)

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