Re: HAL Devices and Streams (with QuickTime)
Re: HAL Devices and Streams (with QuickTime)
- Subject: Re: HAL Devices and Streams (with QuickTime)
- From: Jeff Moore <email@hidden>
- Date: Fri, 18 Jan 2002 12:19:16 -0800
on 1/18/02 11:45 AM, Lieven Dekeyser <email@hidden> wrote:
>
I'm pretty sure MediaSetSoundOutputComponent would accept an
>
AudioDeviceID, but maybe you can set some kind of parameter for the "HAL
>
Audio" OutputComponent to the AudioDeviceID of your choice... Using
>
different devices would be as simple as creating instances of the HAL
>
Audio component and setting the AudioDeviceID parameter of each of these
>
instances.
>
>
can anyone confirm or deny all this?
1) MediaSetSoundOutputComponent takes a Component not a ComponentInstance or
AudioDeviceID.
2) the HAL sdev does have an Get/SetInfo selector to change what
AudioDeviceID it is using. It is, unsurprisingly, siHALAudioDeviceID.
But, and this goes back to what I was trying to get at when I talked about
the Sound Manager's architecture getting in the way, the Sound Manager will
use the same sdev for all the tracks in a QTMovie without being pointed at a
wholly different sdev Component using MediaSetSoundOutputComponent.
To make matters worse, the Sound Manager has to be the one to open and
configure the sdev. It won't accept a ComponentInstance that you've already
opened and configured for the job. And if you pass in a Component of which
the Sound Manager already has an open instance of, it will recycle that
instance and not open a new instance.
Hope this helps clear things up a little.
--
Jeff Moore
Core Audio
Apple