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Timecode syncing multiple GH4 cameras
  • What is the best way to timecode sync multiple GH4 cameras? From reading the manuals and related threads there seem to be two approaches:

    App Method: Use the Lumix Link app to set the timecode for each GH4 to the time on the mobile device and then use Time of Day timecode mode.

    YAGH Method: Use a YAGH to jam true timecode to the GH4 from a master clock.

    The App Method seems easiest and cheapest if it is accurate enough. Has anyone tried it yet with multiple GH4s?

    If the App Method doesn't sync cameras with sufficient accuracy, do you need a YAGH for each camera, or can you attach the YAGH to a GH4 to jam timecode and, once that camera's clock is set, move the YAGH to the other cameras in turn to jam sync timecode. In other words, once the GH4's timecode is set via the YAGH, does the camera retain it when the YAGH is removed? This would let one YAGH serve multiple cameras for timecode jamming purposes.

    Thanks!

  • 27 Replies sorted by
  • I just dump the files on the timeline and line up the waveforms, but I would say try the app first in a little test and see if it is accurate enough for what you want. Theoretically, it should get you fairly close. Obviously, if you have the timecode you will also get pretty close, but you still have to bump it a frame or two even with timecode (timecode doesn't factor distance). Clocks usually drift a bit unless they are slaved to a master clock, more recent cameras tend to have better clocks.

  • Thanks @DrDave . That method works very well for many uses but I have a couple of special uses that require real timecode. One reason why I want multiple cameras to be synched with exact timecode is so that they will all be recording at sub-frame sync. I haven't been able to find out much about the real capabilities of GH4 timecode.

    I will have a second GH4 this week for testing the Lumix Link app method and will report back. However, if anyone has used timecode on the YAGH (or knows definitively) I'd love to know about whether one YAGH can be used to jam sync for multiple camera bodies sequentially.

  • I doubt that you can get sub-frame sync with consumer cameras, even if you find a way to sync TC.

  • @nomad - subframe accuracy is all about your edit software, not camera hardware

  • @DouglasHorn - some edit packages allow you to record t/code on an audio track, and then use that as an auxiliary time code track. As long as you have multiple t/code outputs from a common source, this might be worth looking at. You could also run black & burst syncs to the t/code unit to ensure the time code unit doesn't drift during recording.

  • Subframe sync would be great, I think the timecode on the audio track won't be as accurate as a master clock but pretty close.

  • Thanks for the replies.

    I guess I need to look into the spec a little more. My expectation is that a camera using timecode would start recording on an even multiple of the framerate it is shooting. And therefore any cameras jammed to the same master clock would record the same frame at the same time. My use is about getting multiple cameras synched very closely as well as easing post-production synching. Recording LTC on an audio track won't help with the first part and it's pretty kludgy on a camera that has built-in timecode.

    I'll have a second GH4 soon, so I guess I'll just have to run some tests.

  • Just clap your hands. The trick for mutli-cam is to multi-clap. So if you have 4 cameras, you just clap 4 times. Works everytime.

  • Subframe accuracy between cameras is possible with Triax-connected pro cameras.

    Subframe editing is a feature in NLEs, right.

  • The trick is clap very loud, slowly, and deliberately.

  • @DouglasHorn - not really understanding why an even multiple of the frame rate being shot is in any way significant to syncing groups of cameras, especially if you're using time of day time code. Cameras jammed to the same clock will record the same frame at the same time, and as you can't jam sync the GH4 time code track, recording t/c onto an audio track is the next best thing. Auxiliary time code tracks can be a life saver, and the kludgy part of this is Panasonic's poor implementation of time code functionality.

  • @nomad - pro cameras that will accept an external sync reference will have a frame accurate relationship with any other camera being fed the same sync reference, regardless of cable connection

  • Frame accurate: yes. But there was a question abou subframe accuracy…

  • @mrbill - can you help me understand your expertise level with this so I can assess your comments? That's not meant to be a jab, I just don't know where you're coming from. There are certain people on this forum who have great technical knowledge and I suppose the main point of my question was to see if someone like VK or LPowell had a ready-made answer for this question, before I dive into extensive (and possibly expensive) testing.

    My own understanding of cameras and TC is fairly high--I just don't know the specs on this camera setup--so I'm looking for a high-level answer.

    But to clarify the question on subframe accuracy for TC-jammed cameras. I suppose it comes down to this: Say I've jammed multiple cameras to a single "master clock" -- either real via a YAGH or virtual from the Lumix Link app setting multiple cameras to the same mobile device clock (assuming this is sufficiently accurate--which is one open question), ignoring drift for now (assume sync happens briefly before shooting), then if all cameras are shooting 30P. say, when started, will the cameras shoot their first frame on an even multiple of the frame rate such that when all cameras reach a common timecode (say 1:00:10:00) they will be capturing the same moment in time to a resolution of greater than just 33 milliseconds (1/30th) of a second. Will the camera "wait" a few milliseconds after the REC button is pushed until the next frame comes around (which would lead to subframe-type sync) or does the camera just start rolling and stamp whatever the closest available approximation of timecode onto the video stream as the frame is written?

  • Hi Doug, syncing timecode in a professional multi camera setup used to be done one of two ways with analog gear: 1. Jam-sync. Momentary sync which is frame accurate at the time of syncing. The cameras WILL drift and there is no sub-frame or colour subcarrier sync in the old analog terminology. 2. Continuous sync, where the incoming TC feed is constantly regenerated and has sub-frame sync. You can also use an external TC feed with no regeneration if the camera supports it.

  • @DouglasHorn - ^ what he said! I would also power the cameras from mains as opposed to batteries in attempt to mitigate any drift.

  • There's a dual camera controller for GH/G cameras that can assist in syncing them. It does this by simultaneously powering them on, triggering them at the same time, and monitoring drift through the video output:

    http://www.appliedlogiceng.com/index_files/Page1834.htm

  • Hi, doing that will not precisely sync the two cameras - the frames on each pair of cameras will be recorded at up to 1/2 frame time difference. This means that if you have movement being viewed by both cameras, the movement will be up to 1/2 frame time different between the two. (I know this, having done lots of 3D work where sync needs to be ideally within 1 pixel time.) The only way to really sync two cameras is to have genlock in, which the GH4 does not have (although not sure if the YAGH gives this feature, or just timecode in). So it depends upon the use - if you just want the same timecode then fine, but if you really want the cameras synced then the GH4 is not the camera that you need.

  • There should be a better system.....

  • This is a semi-pro camera at best - there are always going to be workarounds at this price point. @tdbristol - there's an external time code input on the yagh but asfaik there's no genlock in

  • @tdbristol - Thanks. That helps.

    My current understanding is that the only advantage of the YAGH over the Lumix Link app is allowing it to accept sync jamming from an outside TC generator via an SDI cable. It doesn't seem to offer genlock features.

  • There is a better way. I use 'tentacle syncs' 1 per camera. If you are in vicinity of other cameras, you can use 1 tentacle and run 3.5mm to each camera, but if far apart, easier to buy a separate tentacle per camera.

    I've done 5 multicam shoots with this setup, and works flawlessly.

    http://forum.tentaclesync.com/

  • @ricker, How did you do the multicam mode on the tentacle sync software. It didn't work for me. Also after I sync sound and video, one of the camera was out of sync for a good period of time. So I had to manually sync that part with audio I recorded from a zoom H4.

    My set up was, 3 tentacle syncs, 1 as master and two slave to two canon xc10. The master was recording sound to a zoom H4 along with 2 mics.

  • I was using 5 tentacles, 2xGH4's, 4xBMMSC, 1 C300 (jammed with timecode), and a sound devices 10 channel recorder as the master timecode. I split 1 of the tentacles across 2 cameras as they were next to each other.

    When you put it all in tentacle sync software, you simply have to hit sync which then gets it to see all the audio/file timecode on all the files. You then select the files specific to each camera and set them to a group number based on the video track you want them to appear in your NLE.

    I didn't have any issues with sync at all, and we filmed 3 days for around 10 hours each day. I've done it before as well on another similar setup and all worked flawlessly.

    Seriously time savers, would of taken me days to sync this stuff in post.