New, sophisticated MIDI Clock Slave implementation works
I got the new MIDI Clock Slave implementation working: It now consists of a Delay Locked Loop (DLL). Since a DLL has the property of always minimizing the loop error (which means the difference of ARDOURs transport position relative to where it should be according to the latest MIDI clock message), it will even follow tempo changes.
That means, you can change the tempo from 120 up to 400 and down to 40, and after a short time Ardour will be exactly
on the beat again.
Of course you can just use the same tempo as in ARDOUR
and enjoy drift-free synchronization between ARDOURs audio and your MIDI device.