[linux-audio-dev] PTAF link and comments

David Olofson david at olofson.net
Mon Feb 3 20:30:01 UTC 2003


On Tuesday 04 February 2003 00.41, Steve Harris wrote:
> On Mon, Feb 03, 2003 at 02:52:54 -0800, Tim Hockin wrote:
> > > 	* Process mode: Mixed/RT/Off-Line.
> >
> > do we really want anything like this?  I have a 1-10 'quality'
> > level.
>
> Not the same thing. I think offline processing allows seek, reverse
> etc.

How would you handle (audio time?) seeking and reverse processing?

Well, of course, it's no problem if the plugin is *designed* for it...


> > > > 	* Hosts assume all plugins to be in-place broken. Why?
> > >
> > > It doesn't really matter what the default is as long as you can
> > > override it. That way is probably safer.
> >
> > Do we want to do this for XAP?  I'd kind of hoped that XAP would
> > dictate that all plugins must be in-place safe.
>
> Its very inconvienient for certain algorithms. The plugin doesn't
> know ahead of time how big the buffer is going to be, so it cant
> prealoocate an intermediate buffer.

Actually, plugins do know the *maximum* buffer size they can get. This 
is a critical API feature for many plugins.


> > From: David Olofson <david at olofson.net>
> > Instruments: have no inputs (in general) and overwrite output
> > Effects with #ins = #outs: overwrite their output with:
> > (input * dry) + (fx * wet).
> >
> > We can standardize a wet/dry gain control pair.  But this becomes
> > something every plugin needs to provide.  Uggh.
>
> Mix is not the same as wet/dry. Imagine you have an effect with an
> inherant delay of 64 samples, the dry output is the input delayed
> by 64 samples.

Good point. But that also means that plugins with delay *have* to do 
this properly, or they'll ruin the host's efforts to compensate for 
FX latency.


//David Olofson - Programmer, Composer, Open Source Advocate

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