[ggegan]

If you are syncing up multiple Pro Tools they can lock up out of sync on some passes, always a delay in my experience. Also, there is a degree of latency with some plug ins that can account for things being out of sync, even if you are working entirely within one Pro Tools system. Individually these things may not account for a full frame during a single take, but if you stack them up and first record the final and then use the final to create the print master, it can easily add up to a frame. I just had this situation occur on a print master where LT/RT versions that were laid down simultaneously were offset from each other and both were different from the 5.1, which was created from the same session and same tracks. I have often seen situations where Satellite Link occasionally locks up different sessions two or more frames out of sync. Haven't you ever noticed that when you carefully sync up foley to top production, it is slightly different on every pass?

The sync resolution is not as high as it should be. It is, however, no worse than mag systems were due to the displacement caused by the motion filters on the recorders and reproducers.

These things can drive you crazy. On most good sized mixing stages the sound is already 1/2 to 3/4 of a frame late to begin with just because of the fact that each foot of distance accounts for approximately 1 millisecond of delay, so things are never what they seem. In the end you just have to eyeball it and make a judgement as to whether it's within acceptable tolerances based on feel. It's never going to be 100% accurate.