Re: Setting the AU's sample rate
Re: Setting the AU's sample rate
- Subject: Re: Setting the AU's sample rate
- From: Marc Poirier <email@hidden>
- Date: Sun, 4 Jul 2004 18:47:47 -0400 (EDT)
On Sun, 4 Jul 2004, Jeremy Sagan wrote:
>
Marc,
>
>
On Jul 4, 2004, at 6:22 PM, Marc Poirier wrote:
>
>
>> It has recently come to my attention that changing the sample rate
>
>> before doing off-line rendering is crashing at least one AU plug-in.
>
>> Therefore I want to be absolutely sure that this is not a host
>
>> problem.
>
>>
>
>> Is it necessary to AudioUnitUninitialize before changing the sample
>
>> rate?
>
>
>
> It is possible for an AU to support StreamFormat changes while
>
> Initialized, but most do not (and should return an error if you try
>
> to).
>
Yes, for stream format changes I do uninit and init but this question
>
relates to explicitly sample rate changes.
Oh, it still counts as a stream format change though (I know there's a
separate property that you can use for sample rate, but if you actually
look at the AUBase implementation, you'll see that it's just a convenience
shortcut to stream format). If you think about it, it makes sense with
the same logic, since an AU for example may need to allocate an audio
buffer that is a certain absolute duration of time, in which case a change
in sampling rate will require reallocation with a new size, and hence
needs to happen outside of the rendering context. But anyway, none of
this helps explain your real problem here...
>
>> If I do this, the AU in question, does not crash but produces
>
>> silence instead and then the AU is in a weird state (e.g. does not
>
>> display properly any more).
>
>
>
> Do you Initialize again after Uninitializing and then changing the
>
> sampling rate?
>
>
Oh yes, definitely.
Okay, I figured so, but I thought I'd still ask in case that was the
really easy solution. :) Well, I don't know what to suggest then...
Marc
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.