[linux-audio-dev] XAP: a polemic

Tim Goetze tim at quitte.de
Sun Dec 15 21:25:53 UTC 2002


Tim Hockin wrote:

>Ok.  So how does a plugin know about musical milestones, then?  Suppose it
>wants to lock onto a beat edge.  I agree that TICKS events are not needed,
>since if you know the sample rate (you do) and you know the tempo (you can),
>then you can extrapolate a tick-width.  The tick edge is the trick.  Or do
>we not worry about it and assume that the user will start things at the
>proper edge, and plugins will just need numbers of tick-widths?

i usually intersect the beat interval giving function with 
the current processing cycle. i don't quite know what you
mean by milestones, it does sound like meta-information to
me (like "begin song part A here", "isolde stirbt", etc).

>I don't get what you were saying about virtual time.  Let me try:
>frame-count is a global rolling counter.  It never stops, unless the host
>has a special 'off' mode.  Ticks is a mucial counter starting at some point,
>0, that represents the timeline (track/song/whatever).  It can jump forward 
>(12, 13, 165) or backward (165, 166, 1) or loop, or pause.  If it is paused
>or stopped, the frame-counter is still going.  Since plugins just track
>'ticks' by that, they still work.
>
>Is that correct?

it's much simpler. imagine the transport time rolling on 
through a 'stop', and some plugins handling things a bit 
differently.

tim




More information about the Linux-audio-dev mailing list