Subject: Re: [linux-audio-dev] PTAF link and comments
From: David Olofson (david@olofson.net)
Date: Tue Feb 04 2003 - 03:22:31 EET
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@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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