Timecode accuracy

Most pieces of professional audio and video gear designed for sync sound recording workflows run timecode, so that editors can easily match up picture and video which have been recorded separately.  However not all of them can be trusted to run on their own without drifting out of sync.  In order for equipment to avoid slipping out of sync, very accurate clock circuits must be used, which require specialised circuitry (temperature controlled crystal oscillators or TCXO).  They’re also expensive, so manufacturers often don’t implement them in their products.

I’ve gone through a load of manufacturers specifications to try and find timecode accuracy in equipment and here’s what I found.  I couldn’t find any specs for timecode accuracy in a number of products, in fact no cameras meaning they need to be attached to an external source.

Also, timecode alone will not stop picture and sound files being different lengths.  High accuracy clocks are also required to feed wordclock on audio devices and genlock on video in order to slave other devices to these rates, otherwise you’ll experience a difference in file length in accordance to how much your clocks are drifting.  This can be especially bad on long takes or syncing up live broadcasts
Also each of these figures goes for the accuracy of one source at maximum (specified) drift.  if using two of the same source, these figures should be doubled.

TC Source TC accuracy (parts per million) Time to drift 1 frame (mins) @30fps
Sonosax 1 555.55 9hrs 15mins
Zaxcom 1.54 360.7468 6hrs 1min
Tascam (specs from HS-P82) 100 5.5555 5mins 33s External Sync necessary
Ambient* 0.2 2777.75 46hrs 18 mins (requires tuning for this accuracy)
Ambient ACN 0.1 5555.5 92hrs 46mins
Timecode Buddy 0.16 3472.188 57hrs 52mins
Fostex (specs from PD606) 100 5.5555 5mins 30s External Sync necessary
Roland (specs from R88) 15  37.3737 37mins External Sync necessary
Denecke 1 555.55 9hrs 15mins
Betso 0.2 2777.75 46hrs 18mins

 

*in Sound Devices 7 series and 664, AETA 4minx, ARRI Alexa and Pre- ACN Lockit boxes

Updated to include Roland R88

3 Replies to “Timecode accuracy”

  1. Hi Richard,

    Thank you for theses specs. Do you know with which of these recorders (or other ones) it’s possible to use a GenLock in, in order to start the record from the camera ?

    Thanks

  2. Hello Richard,

    I believe you misinterpret the spec sheet from Tascam. I’m not entirely sure what Tascam might be trying to say when they write “Allowable frequency deviation of external sync +/- 100 ppm” in the HS-P82 manual, but I don’t believe that they refer to time code accuracy, if only because it would be abysmally bad. Any cheap quartz watch is more precise than that, by orders of magnitude.

    1. Sorry about that- you appear to be correct, looks like that’s the deviation that the sync in connector will deal with. A colleague of mine owns this machine and has reported from experience that it’s usually pretty stable for an hour or two, however he’ll usually run a sound devices recorder just as TC master

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