Re: Device input format change.
Re: Device input format change.
- Subject: Re: Device input format change.
- From: Tommy Braas <email@hidden>
- Date: Fri, 2 Feb 2007 08:39:10 +1100
Thanks for your speedy response Jeff.
We allow our users to modify the device settings, as they expect to
have full access to all formats provided by a device from inside our
recording application. We'd like to be able to modify device settings
as robustly as it is done in AMS, which we currently apparently are
not doing.
After changing the property on the AudioDevice, we do indeed wait for
the callback to occur before we proceed to start the device. All we
do in the IO proc is pushing the received audio samples to an
AudioFile via an AudioConverter.
We are not currently using AudioUnits. Would using the HALOutputUnit
for input, in your opinion, help resolve this issue?
Kind regards,
\tommy
On Feb 2, 2007, at 6:18 , Jeff Moore wrote:
First off, the general rule of thumb is that applications should
not be fiddling with device settings. Settings belong to the user
and should be set using the system apps. Obviously there are
exceptions to every rule, but most apps should respect the settings
the user has already made.
That said, the problem here is probably due to your app not using
the correct format in your IOProc. The usual mistake that gets made
here is assuming that the format you set is the format the device
actually is using. The other common mistake is assuming that the
format change takes place immediately, when in fact changing the
format is an asynchronous operation that can't be deemed complete
until your listener proc gets called indicating that the format
did, in fact, change.
On Feb 1, 2007, at 11:05 AM, Tommy Braas wrote:
I am currently facing a problem when changing the input stream
format on a recording device using HAL.
When it is done in my application, the device ends up generating
pink noise. When the device is set as the default system input
device and the input stream format changed using AMS, there is no
pink noise!
Can anyone speak to what the issue might be here, or at least
describe the recommended sequence of input stream property changes
in HAL?
--
Jeff Moore
Core Audio
Apple
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