Re: Getting Default Output Device gives a strange answer
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 12:21:46 -0800
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.
On Nov 14, 2006, at 12:11 PM, Andrew Kimpton wrote:
Quoting Jeff Moore <email@hidden>:
A value of 0 for an AudioDeviceID is defined in AudioHardware.h to be
kAudioDeviceUnknown. In this context, it is to be taken to mean that
there is currently no device capable and/or willing to be the default
device currently.
Also, not having a default device when asked is not an API error,
hence
no error code will be returned.
Ok - that makes sense - but leads to the next question :
Under what circumstances would I not have an output device on an
Intel Mac Mini with only it's built in audio hardware ? is it
related to a previously aborted Hog mode state ? Is there a
programatic recovery method or must I (and any user in a similar
state) reboot (or run AMS to reset things ?)
--
Jeff Moore
Core Audio
Apple
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