Re: MP audio output
Re: MP audio output
- Subject: Re: MP audio output
- From: Bill Stewart <email@hidden>
- Date: Thu, 21 Mar 2002 12:28:26 -0800
on 21/3/02 11:11 AM, Jeff Moore wrote:
>
on 3/21/02 10:49 AM, Kurt Bigler <email@hidden> wrote:
>
>
> Suppose I instantiate two connections to the default audio unit for output.
>
> Then I get two callback threads, right?
>
>
If your connections ultimately end up talking to the same device, you won't
>
get two IO threads, just the one. The HAL will only run a single IO thread
>
per device per process.
>
Futhermore....
The OutputUnits (whether the HAL, Default or System) are designed to
represent the format of the device to their clients...
Thus, if a device has a single stream (for eg. Built-in hardware), then
you'll only be able to connect input to it on the output unit's element==0
(ie. One channel/bus)
If a device has multiple streams, then the elements (buses) of the output
unit represent in the same order, the signal path for each of the streams
for the device.
Thus, there are things they don't do:
(1) They don9t mix - If you need to mix, you should have a mixer sitting on
top of the output unit's input buses
(2) You can only establish connections to the output unit based on the
stream configuration of the device itself - where element (bus) 0 relates
directly to the first stream of the device, element (bus) 1 relates to the
second stream of the device, etc...
Finally, as Jeff said, all of these streams will be fed on the same thread.
Bill
mailto:email@hidden
tel: +1 408 974 4056
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