Only two I can come up with are:
- The pay version of JJOS for the Akai MPC's, which would require additional SMPTE to MTC conversion, if you wanted to start from audio-tracked sync
- The JL Cooper PPS 100, which does actually quite a number of different sync conversions, but they were made in the early 90's and are getting scarce
Seems like the biggest issues faced if it works would be Start position on the correct bar/measure/beat and any additional latencies produced by conversion. If anyone can testify to either of the above two as being reliable or can suggest something else, I'd be very grateful.
If you're wondering why the interest in SMPTE, it's mostly because I want to eliminate jitter in having my PC act as the primary sync source for several external gear items that either use Midi clock or convert Midi clock to pulse clocks or Sync24. Audio-based sync, in conjunction with rock-solidly timed external Midi devices, seems the only logical choice.