[linux-audio-dev] XAP: Pitch control

Steve Harris S.W.Harris at ecs.soton.ac.uk
Mon Dec 9 12:51:01 UTC 2002


On Mon, Dec 09, 2002 at 05:37:53PM +0100, David Olofson wrote:
> On Monday 09 December 2002 17.05, Steve Harris wrote:
> > I really dont like the idea of having two forms of pitch data, and
> > I dont like the idea of implicity putting pitch converters in the
> > graph.
> 
> Well, it can be done with one form only, that will only make life 
> harder on those who don't want to truly understand non-12tET scales.

No it wont. Code that doesn't want to deal with scales doesn't have to.
Code that wants to deal with notes can just make a call to ge it
converted.
 
> > Its messy and unnessary.
> 
> It may be messy if done wrong, but I strongly doubt anyone on the VST 
> list would agree that it is unnecsessary. They convinced me, at least.

But the VST people were allready lumbered with note scale, that puts
them in a different situation.
 
> > The overhead from making the small number of processors that
> > require it get the host to do the conversions is probably no higher
> > than having converter plugins and its so much cleaner.
> 
> It's not cleaner in any way, since for this to be useful, the plugin 
> has to figure out what scale it should ask about.

Not really. Unless the plugin explicity wants to use a different scale to
the session one it can just ask for the default. Its pretty uncommon for
people to mix scales in one session.

Infact the nearest example to this I can think of is with clashing
subsections of a microtonal scale, but that is still one scale. Though I'm
sure, someone, somewhere has really done it.
 
> Again, there is no such thing as a single, global scale. If you 
> assume that, you may as well ignore anything about non-12tET 
> altogether.

Huh! I'm not talking about global to the world, just global to that
particular graph. Granted there will be people who want to run half thier
track in 12 and half in 7, but thats hardly a common case, and we dont
prevent it.
 
> Well, yeah - presets. Just like with any other plugins. A scale 
> converter is an *effect*, and deserves to be treated as such by the 
> API.

Its not an effect, its a conversion. It should be lossless. If its an
effect then the algorithm is wrong.

- Steve



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