So the editor of this period drama says to me last week, the sync is out, and also commented that the 2nd unit recordist was as much as 5 frames out of sync.... now first of all let's says there's a 2 frame offset.. that still leaves 3 frames adrift.

I use the ambient lockit boxes on arri d21 cams, the master clock however is a ambient acc501... so I tune the lockit boxes to the 501.... half way thorugh the day I re-jam and at most the difference is around 0.04 - 0.25 of a frame out.

My mixer's box is a denecke and I jam this too, however it does not have a timecode out so I cannot check the diffence.

So with such tight sync between all devices, basiclly less than a frame how is it possible that the editors, bless them, are saying the sync is out by more than 3 frames in some cases?

Later on they told us, doesn't matter if it's out, it's out.... I wonder do they really know what timecode is and are they syncing it in post correctly?

I use time of day free run, 25fr, 48khz non dp.

I wonder if the problem could be with the mixer's fostex recorder as this is the only mixer to have a setting where you set the frequency to 48048 but it gets stamped at 48k, making the playback of the recorded audio 0.1% slower?

The 2nd unit mixer uses the same Fostex dv824

Any comments?


1 Answer 1


Just to clarify: Is the offset consistent or does the sync drift more and more over time? In my (admittedly limited) experience, consistent timecode offsets of 1-2 frames even with top-notch kit isn't uncommon...but it's pretty easy to fix. Drifting sync over time could absolutely signify a mismatch in sample rate that you yourself diagnosed, or someone's sync box or internal clock not set to match drop vs. non-drop. How much post will complain or be willing to fix it depends on how consistent the problems are - if it's all over the place, they're right to have conniption fits.

Colin's got a lot of experience doing production audio, he might be able to chime in with more knowledge.

  • Well offset wont drift more because its an option so once set, its set. so Fostex by defualt have a 2 frame offset I forget the reasonng behind it. But as for the drift outside of the offset, according to the acc501 in a whole day the drift is never more tahn 0.25 of a frame. As I mentioned i dont jsut jam I tune them to within 2ppm. So in a day 0.25 drift at most... so I cannot figure how the editors are getting upt to 5 full frame drift. Unless the recorder on the arri is a bit pathetic... but then its being controlld by a lockit box so should be tight.
    – Sharpy
    May 2, 2010 at 18:04

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