Need a bullet proof workflow to sync up with an external audio

7.38K viewsSoftware

I shoot at 60p (59.94) but deploy to a timeline of (30p 29.97)

I own 2 tentacle units and am able to sync 2 video cameras with no issue BUT

I can never get my video to line up with an external audio source such as an h4n.

The audio of the external source is constantly drifting.

Please help me develop a workflow so that I don’t spend hours on this every project.  Tentacle was supposed to save me time but so far it hasn’t fulfilled it’s promise.


Thank you


How fast is the drift?
What frame rate are the tentacles on?
Can you make a screenshot of the files in Tentacle Sync Studio


Hi Fokke, thanks for your reply.

I’m setting the tentacles to 29.97.

I shoot for over 4-5 hours at live events and so the drift is pretty substantial at the end.

My h4n produces one or 2 long files and so by the time I’m at the end of the audio the drift is huge.  Now when I use FCPX to take the timecode of my DVX200 and the audio it matches perfectly, but If I try and export both camera footage from tentacle studio into a multicam clip and then lay the audio file on top the audio exceeds the length of the entire shoot.  I tried exporting to both a 29.97 project and a 59.94 same result.  Audio matches at the very beginning but then goes about 110% or more past the end of the video.


Hi Ari,

can you mail me a screenshot of the files in Tentacle Sync and the resulting XML file to support (at)

I will have a look at it.



Thanks Ulrich,

I sent the email to support with your name in the subject line.



edited answer

Timecode is not a sync signal. It is a way to line up.

What that means is this; you put a timecode signal on the file but the camera’s and recorder will still run at it’s own clock.
Read This

If you don’t put a Tentacle on the video and audio recorders you will get the same result; Align them at start, you will find drift at the end. Because they run at their own clock. The only thing the Tentacles do is to line them both up for you. At start, in the middle or at the end.

For short runs that is not a problem. For longer runs, it is. You have encountered that

There are a few options for you.

1. Make short stop-starts more often if you can. Each start will be re-synced.

2. Use better Audio (and/or Video recorders) that have better clocks, or even better; have WORD clock inputs and GENLOCK inputs.

That way they can run at an external clock. Then you need cables between them or you need a box like Ambient Lockits that have genlock out. But your camera’s and recorder don’t have such inputs.

3. You could also use Plural Eyes to sync instead and enable Drift Correction. I would never do that myself as i don’t want software that will time stretch my audio.
I hope i helped some.

edited answer