Synch clips out of synch FIX?

[Joe Marler]

You have two different issues: (1) Atomos A/V sync issue and (2) FCPX use of sync clips not multicam clips.

My doc team has many Atomos recorders and we’ve never seen this. We use both Sound Devices and Zoom F8 recorders.

However — a 4-8 frame sync issue on some Atomos recorders is commonly discussed, not just by FCPX users. Maybe other Atomos users could comment with their experiences.

Here is an interesting video discussing this: https://www.youtube.com/watch?v=5ug6B3-RF04

Problem #2 is using a sync clip not a multicam clip. It is generally better to use a MC clip, even when only having one video and external audio source. One reason is MC clip ranges in the timeline continuously inherit the properties of the parent clip in the Event Browser. Thus if you edit 50 clip ranges from a long MC clip into the timeline then discover the color or audio sync is off, you can simply open the parent MC clip, fix that, and all 50 sub-clips in the timeline will inherit this. Sync clips don’t exist in a parent/child relationship so this isn’t possible with them.

You can also selectively re-sync an existing MC clip, add angles, add audio sources, etc.

This is discussed in this Frame.io blog post by T. Payton: https://blog.frame.io/2016/10/06/6-ways-to-maximize-multicam-fcpx/

The proper practice is batch label all clips from each camera or recorder in the Inspector with a specific camera name or angle name, sync the multicam, then open the MC clip and check the sync (beginning, middle end), then in the Event Browser mark favorites and keyword ranges in the MC clip, then insert those in the timeline. Do not put the original parent clips in the timeline. To help avoid this mark the parent clips “rejected” and run the Browser in “Hide Rejected” mode.

FCPX does not do sync drift correction like PluralEyes. If you have very long takes it is conceivable the sync could drift if the camera timebase is poor. Check whether the MC clip is consistently off the same # of frames or just at the beginning, or middle.

Once multiple MC clip ranges are in the timeline, you can still open the parent MC clip in the Event Browser and change color or re-sync the audio. All child clips in the timeline should inherit those changes.

Note if you create a project snapshot, that breaks the parent/child relationship for that snapshot project. Subsequently editing that snapshot means you cannot then change the parent MC clip and have the snapshot project inherit those changes. If you want that use “duplicate project” instead of “create snapshot project”.

Lastly, a good way to ensure sync in a stop/start shooting environment is using Tentacle Sync devices. There are other products but we use these and they work very well: https://tentaclesync.com

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[Nicky Velasquez]

JM thanks for the reply.
Your suggestion is exactly the future I expect to pursue.
I have called atomos about the audio delay feature not working on my unit. I cannot currently change the delay on the atomos – this doesn’t fix the project recording I am wresting with. And as practice I always edit a duplicate rather than a snapshot.

However, I am asking about a potential current fix.
Right now I am manually RE-synching EVERY CLIP in my TIME LINE. (Much like the MC approach.)
Can I move the synch clips “synch” and affect all instances in all projects?

iMac 2.8GHz Intel Core i7
FCPX 10.1.2
OSX 10.9.4

[Joe Marler]

[Nicky Velasquez] “I am asking about a potential current fix.
Right now I am manually RE-synching EVERY CLIP in my TIME LINE. (Much like the MC approach.)
Can I move the synch clips “synch” and affect all instances in all projects?”

Since sync clips in the timeline do not inherit changed properties of the parent clip in the Event Browser, it will be necessary to adjust each timeline clip. I am sorry about that, but that’s one advantage of using a multicam clip vs a sync clip. Maybe someone else has a better suggestion.

I don’t understand how the problem happened. We have 4 or 5 Ninja Vs plus Blackmagic recorders and we use them frequently. I have never seen this problem. We record audio both directly into the Ninja also via HDMI – both ways. The audio delay on our Ninja Vs are set to 0 frames. All are on the latest firmware, but I never noticed a delay problem on the original firmware. Some of them use LUTs and some don’t. This is mostly UHD 4k/23.98 ProRes via HDMI from Sony A7R3s, Panasonic S1 and BMPCC4k.

You are probably aware of this, but anytime you deal with digital video and separate audio there is a possible sync issue due to digital processing delays. You normally see it on venue systems where video goes there via HDMI but analog audio is processed for a PA system. There is an HDMI lip sync delay protocol whereby the monitor informs the HDMI source of its video processing delay and the source is supposed to delay audio to match. This doesn’t always work, esp. in multi-display systems. For an HDMI recorder I don’t know how that works, but so far I haven’t seen a problem on either our Atomos or Blackmagic recorders.

From your description it appears the recorded Atomos video and scratch audio are out of sync several frames and this out of sync condition persists if downloaded to the NLE. Then when you synced external audio to the scratch audio that was likewise delayed since it synced to delayed audio.

When you are playing back the Atomos material, is it delayed if played back locally on the Atomos if listening with headphones, or is it only delayed if that same material is played in the NLE or via Quicktime? I guess it doesn’t make any difference – it must be fixed in the NLE, I was just curious.