Re: [LAD] External midi sync

On January 23, 2010 11:36:36 am you wrote:
> On Sat, Jan 23, 2010 at 1:23 AM, Tim E. Real <termtech@email-addr-hidden> wrote:
> > I can imagine sync was a tougher nut to crack in Ardour.
> > MusE's ticks per quarter note is fixed at 24, although
> > the 'frames per quarter note' (hence division) is variable.
> > And you'd want sub-tick (frame) resolution in an app like Ardour.
>
> MIDI clock, which is what you're syncing to, is fixed at 24 msgs per
> quarter note, so there is no difference there. Ardour syncing to this
> is no different than MusE.
>
> > I want to get our MTC code working. I've got the rate
> > detectors working and have monitored input from Ardour Ok.
> >
> > Question: Ardour supports many different timecode fps
> > but MTC only has two bits for the fps.
> > How are these other fps supported? Not for MTC
>
> MTC only supports these rates:
>
> enum MTC_FPS {
> MTC_24_FPS = 0,
> MTC_25_FPS = 1,
> MTC_30_FPS_DROP = 2,
> MTC_30_FPS = 3
> };

>
> the pull up/pull down "rates" are not really rates at all - just rules
> about computing time.
OK. I was curious if Ardour had somehow taken advantage of
 another 2 MTC SMTPE format bits undocumented or something !
Do you mean rates like '60fps' are 'virtual' rates dependant on the
 pull-up/down? (Darn I should know this...)

>
> MTC can be hard to sync to because the MTC transmitter can be bursty.
> Torben Hohn recently applied some relatively sophisticated control
> theory to the problem (in ardour3) which we believe should optimize
> things but we haven't had a chance to really test it in depth yet.
I studied MTC and SMTPE and a few variants in detail, it's a bit weird.
Guess it comes from its 'tape' lineage.
Cool that it can go backwards, though. What a brain twister that is!

FYI Just committed some (more) midi sync, MMC, and MTC fixes to MusE.

No transmit/receive sync with MTC yet, just transport start and
 display of SMTPE format.
I just don't know how I'm going to deal with MTC sync yet !
Tested OK so far with Ardour and Rosegarden.

Question: What happened to Rosegarden's ability to sync to
 external midi clock? The option is no longer there, so it just runs
 on its own time. I'm sure it had that option before.
You mentioned support in Ardour 3, which will be nice.

Tim.
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Received on Sun Jan 24 08:15:02 2010