Re: User-land CoreAudio driver and Leopard
Re: User-land CoreAudio driver and Leopard
- Subject: Re: User-land CoreAudio driver and Leopard
- From: Jeff Moore <email@hidden>
- Date: Thu, 15 Nov 2007 14:21:41 -0800
On Nov 15, 2007, at 12:53 PM, Stéphane Letz wrote:
So I implemented a start/stop notification mechanism based on
CFNotificationCenterPostNotification/CFNotificationCenterAddObserver
(CFNotificationCenter.h)
so that the jack server notify the JackRouter plugin.
- in the JackRouter I guess the plugin constructor is called once
when the application is loaded
This is correct. The only time the HAL loads user-land plug-ins is
when the HAL is initialized.
- the created plugin object is kept in a static global variable so
that:
HP_Device does this through it's sInstance member variable.
- if a "stop" notification is received from the jacks server, the
instance can be used to call the "Teardown" method (so that the
plugin is removed for the application)
- if a "start" notification is received later on from the jacks
server, the global instance can be used to call the "Initialize"
method (so that the plugin appear again for the application)
This is going to fail if the Jack server crashes and never sends the
stop notification.
This work more or less, but:
- it seems the insteraction with "coreaudiod" does not always work
(thus this incorrect displayed device list remains..)
- and sometimes it crash in the "Teardown" or "Initialize" method
Is there a better way for the start/stop notification called in the
pluging to remove/restore the plugin?
You don't want to remove/restore the plug-in, you simply want to make
your device (and other objects) go away. Typically, this just involves
calling AudioObjectsPublishedAndDied() for the objects that are going
away. Then when they come back, you get new object IDs with
AudioObjectCreate() and call AudioObjectsPublishedAndDied() to make
the objects visible.
--
Jeff Moore
Core Audio
Apple
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