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Re: Virtual Device Questions

These don't become "independently controllable" just because you've created multiple "devices" - they still all factor down to one piece of hardware, which has whatever constraints it has, and any changes you make to these will affect all of the virtual devices...

Each process can already use the same device, and has its own "control" over the device - primarily, each process can run the device at its own latency (I/O size), so process one can run 64 sample I/O's and process 2 can run 512 sample I/Os, etc... You can do this because I/O is defined at the process level (not at the device level).

There is also a defined property for default stereo input channels (just as for output), but to be honest I'm less sure about the support for a default input channel... Most apps that do input have some input channel selection capability, so I don't think you'd really need to do this - just use the app's UI

Bill

On 29/06/2006, at 2:59 PM, Mike Silva wrote:

Thanks Bill!  That worked.

Out of curiosity, can I do the same for a multi-channel input device? Can I
sub-divide it into multiple 'devices' that are independently controllable?

Mike


On 6/29/06 5:35 PM, "William Stewart" <email@hidden> wrote:

You can make multiple virtuals (aggregates with just the one device
in it) - one for each of the stereo channels you want.

Then, make sure that for each of these you set the default stereo
pair to the 2 channels that you want to use for that particular device

Apps that are doing stereo output are expected to honour the stereo
pair designation - for instance, both iTunes and QT will, and I'd
expect VLC to as well.

As for efficiency, this depends in part on how the device is
constructed. For instance, if the device publishes its channels as a
collection of stereo pairs, (or mono channels), then the output units
that we provide (AUHAL, etc) will turn off those channels of the
device that aren't being used.

So, I think what you need can already be supported.

Bill

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 >Re: Virtual Device Questions (From: "Mike Silva" <email@hidden>)



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