Multi-cam causing Shift in 2K/4K GoPro Clips?

RedRob-CandlelightProdctns wrote on 3/11/2020, 8:49 PM

While I haven't done robust troubleshooting yet -- I've had two projects in a row now where GoPro events on my multi-take multicamera track got shifted by some amount -- sometimes as much as appx 30 seconds (not minor frame-slippage), and we're pretty sure things were aligned within a frame or two to start.

In both projects it was our GoPro footage that this happened on -- 7 cameras in total, two of them being GoPros, probably both shot 2K or 4K. It's possible I built the multi-camera multi-take track before creating proxies (in case that makes a difference here).

Has anyone seen this happen before? Just trying to get some preliminary theories here.

(V17, latest build)

Comments

RedRob-CandlelightProdctns wrote on 3/25/2020, 5:51 PM

UPDATE: still happening

I found that this has nothing to do with it being GoPro clips and more to do with the fact that they're spanned clips each being about 10 minutes in length (unlike my Canon/Sony clips which are full-act length of 1+ hrs).

I believe nearing the ends of those clips is where this is causing weirdness, but oddly, it extends past that one event and onto other events where that media was part of the multicamera takes. Possibly related to looping at the clip's end, but I don't think so. Possibly relating to changing the beginning or end of one of those multi-take events. Still trying to get to the source .. working with my main editor.

Dexcon wrote on 3/26/2020, 6:26 AM

Does the frame rate (i.e. 24/25/etc fps) of all your footage GoPro or otherwise exactly match the frame rate of your project settings? And is all footage at constant frame rate? Any at variable frame rate may well be a problem.

Howard-Vigorita wrote on 3/27/2020, 2:45 PM

I sometimes have issues with segmented multicam clips. I put them all in a locked group before creating the multicam track but they come out ungrouped and unlocked when I expand them and I occasionally notice some of the clips have Vegas markings showing they've been moved a little. The text is in red so they're easy to spot. Have the idea its cause of some funky mouse clicks I did when undoing a cut. Undoing cuts strictly with ctrl-z helps minimize that. Occasionally I find little pieces of clips buried under a track layer under the clips that were shifted. It seems to happen less often if I switch to the envelope tool and make sure all the clip looping switches set are to off as well as setting Vegas to not align to frames. I don't usually ripple edit till later but I can see that leading to trouble. I find it also helps me spot problems like that if I choose to not keep unused take clips when I expand the multitrack but then Vegas tosses all the crossfades requiring them to be reapplied which kind of precludes my setting the lock switch on all of them.

RedRob-CandlelightProdctns wrote on 3/27/2020, 3:04 PM

@Howard-Vigorita Is it your sense that this happens because you've made an error of some kind during your editing, or because of some quirk relating to clips that are shorter than others in your multi-take multicam track? We've also found tiny tiny (1 frame or less) events in those places too which are a real PIA to find and remove.

My sense is that there is a bug/quirk which is causing this, which could be addressed by the developers if we can pinpoint/articulate/document how to reproduce.

Howard-Vigorita wrote on 3/28/2020, 1:15 AM

I'm not sure how the fragments get out of place but the Vegas multicam track creation scheme creates clip fragments in tracks above and below any track that contains clips separated by a gap. Some of the footage I get for edit is shot by cameras that drop frames between segments which leads to fragments all over the place. I think they'd need to revise the scheme to preclude all those crumbs from falling between the cracks.