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Re: AU "offline" processing
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Re: AU "offline" processing


  • Subject: Re: AU "offline" processing
  • From: Alberto Ricci <email@hidden>
  • Date: Tue, 4 Feb 2003 09:30:16 +0100

At 6:13 PM -0800 2/3/03, Bill Stewart wrote:
On the first issue (can an AU have different sizes of audio data on in and out) the general idea has been:

AudioUnit - Effects
They leave the data sizes unchanged

Format Converters
They don't:)

Then I agree on your proposal to introduce yet another audio unit type that is not necesarily required to leave the data sizes unchanged.

But an issue comes to mind - how would these AudioUnits inherit the additional stuff that MusicEffects get, compared to 'aufx' effects? Would we need to define new types for all combinations of multiple inheritance? This would easily become a mess.
At that point, why not use 'aufx' effects and specify a new property that tells the host whether the AU is strictly 1-1 or not?

After all, AFAIK, the fact that AU Effects leave the data sizes unchanged is just a convention. The class itself allows for different buffer sizes.

I think we're still in time to introduce a property that hosts should carefully examine, now that there is only a handful of hosts...

With the host apps we've concentrated on the hosting of the 1-1 effects based units as that seemed to us the most common case of existing DSP and so forth. However, I'd talk to the host app companies about also providing the capacity to host 'aufc' units for this kind of functionality - we could define another audio unit type if we wanted to distinguish between more run of the mill format conversions and musical effect type conversions (like time-stretching)... ('auxf')...:)

In my mind, I would introduce a new AudioUnit type iff it requires adding new methods to the base class.

If, on the other hand, all can be done through properties (whether existing ones or new ones), I would not introduce a new AU type.

Maintaining this correspondence between AU classes and AU types seems to me a pretty simple and intuitive rule. Having two different AU types use the same base class would make things confusing and there would still be the problem of multiple inheriting classes such as MusicEffects that don't process 1-1.

Alberto.
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 >Re: AU "offline" processing (From: Bill Stewart <email@hidden>)

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