[linux-audio-dev] What parts of Linux audio ....Tempo Maps

[Tim Orford]

On Mon, Jun 20, 2005 at 07:34:28PM +0200, Florian Schmidt wrote:
> > you can't do tempo-map based transport without sharing the tempo map.
> > nobody has suggested a way to do this yet. please feel free.
> 
> Here i would like to chime in :) I think the mapping of BBT to frames
> and the other way around isn't something that jack should be concerned
> about. IMHO jack should only provide transport based on frame numbers.
> 
> Everything else, like different apps trying to agree with other apps
> which frame corresponds to which BBT should really be handled by a
> different mechanism.
> 
> The reason for this opinion of mine is that musical time is simply too
> complex to be handled by one general mechanism. Think of different apps
> using different meters, etc.. Or even a single app using different
> meters on different tracks syncing to another app with yet another
> meter. 

I dont see how a shared tempo map could be useful for these complex situations,
unless you are arguing for multiple shared tempo maps, which actually is
not much more complicated to design than a single map (although more
confusing for app devs)?

Usage of the tempo map by an app would be optional of course, so a
"simple" map in Jack would not preclude use of other sharing mechanisms. 

Surely having each app separately calculating its own musical positions 
is a recipe for disaster, ie lack of solid sync? 

> IMHO the notion of BBT/tempo/etc. should be local to apps and if needed
> be shared via another lib (which, if it finally settled down and became
> quasi standard could again become part of jack). 

Yes it should ultimately go in Jack, imo, as there doesnt seem to be any
reason against.

(No doubt i have overlooked several important details!)


go Florian!!
-- 
Tim Orford