> While some devices do calculate the tempo *and* use it, many do not.
>
> What they do is simply "count clocks" and use that as a time base.
>
> If there were only 2 clocks per beat then swing would work easy enough.
> ...but trying to sort out the timing for 24 ticks ( or whatever the actual figure is)
> to produce a swing in the slave machine 12 of those ticks would have to
> be drawn out, and the other 12 sent quicker to compensate.
>
> Generally getting the BPM from midi clock just isn't accurate enough
> for syncing.

Right. So the simpler devices that just count the clock pulses shouldn't really have a problem. As they're not trying to do anything fancy such as extrapolate a tempo, they're just counting and incrementing and chugging along quite happily, blissfully unaware that the fluctuations in timing might signify swing or a tempo change or anything else.

The only thing I've really done with MIDI clocks and DIN sync clocks in recent years is hook up my partner and I's homebrew step sequencer to an MCV-24. Our sequencer just counts the clock pulses coming in from the MCV-24, which in turn is translating the MIDI clock signal it gets from Reaper. I threw in some tempo changes, and it worked perfectly, to my ears. Counting DIN sync pulses is really quite a neat solution. It's simple and elegant.

All the best,
Zoë.