Re: how to tell if you can change a data source under program control
Re: how to tell if you can change a data source under program control
- Subject: Re: how to tell if you can change a data source under program control
- From: "B.J. Buchalter" <email@hidden>
- Date: Fri, 20 Sep 2002 14:27:47 -0400
>
Data Source controls are totally supported on a per stream basis. The
>
HAL has explicit support for this. The HAL looks for a control
>
attached to the IOAudioStream object with a channel of 0. It uses this
>
control for the master on that stream.
>
>
This is exactly why the HAL makes such a big deal about the difference
>
between device channel 0 and stream channel 0. They refer to different
>
places for attaching controls in the driver.
Aha. Sorry -- my bad. I guess the fact that the AM app and Daisy don't show
controls on a per stream basis is what threw me off. Thanks for clarifying
that, Jeff.
Ok. So source controls should be attached on a per-stream basis, and the
stream structure is a good way of informing the clients what the control
scope is. Another good reason for multiple streams per device.
Best regards,
B.J. Buchalter
Metric Halo
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