I was having problems, getting MIDI-clock / realtime-MIDI to work in PureData. When I start receiving a MIDI-clock-signal freshly for the first time after starting PureData everything works as expected. PureData received the realtime MIDI data. (I use this patch for deriving the clock-data: http://little-scale.blogspot.de/2013/03/dealing-with-midi-clock-in-pd-sync-pd.html).
But now... when I stop the clock and restart the thing, I always got the error "warning: MIDI timing FIFO overflowed" in pd-console. I am using Ableton Live 9 as host - MIDI is going over the IAC driver on Mac OS-X. Search on the web only brought old websites and no solution to this, so I experimented a little bit myself and maybe found a solution:
What helped was the following: By coincidence, I went to the "preferences..." setting-panel. There I turned of the "Realtime Termination"-flag (I have the version in German, there is it called "Echtzeit Terminierung" - maybe the English translation differs.)
Does anyone knows what the Reatime-Termination Flag does? Any why this is solving the realtime-MIDI-issues that occur with receiving MIDI-clock signals? I just want to be sure, that this is really solving the problem.