Waveform sync will link clips that don't match

I just synced a whole feature - doing relatively small batches by waveform syncing one shoot-day at a time.
LOTS of mistaken syncs. Things that don't sound remotely alike.

What I found by looking at the tracks were that there were TWO SETS of linked audio tracks - one that appears to be from the correct audio take and one from a completely different one. This second one is shown in the media pool entry as the synced audio.

Here's a video showing Resolve incorrectly linking two audio files - one the correct one plus a second "random" one:

Hmmmm.

For unique clips, I think syncing by audio should be fine. But for a multi-take situation, where the audio in the takes will be very similar, syncing by timecode seems like it would be the better option.

Of course, you have to plan for that ahead of time.

If you didn't, you might have to sync the clips one at a time by selecting the specific matching pairs.

So you're saying that you think autosync isn't up to the task.
If that's so then it's broken and should be fixed.
Suggesting that I change my clients' workflow before they've even become my clients is... not likely.

So you're saying that you think autosync isn't up to the task.

No, I'm saying for unique clips, I think syncing by audio should be fine. But for a multi-take situation, where the audio in the takes will be very similar, syncing by timecode seems like it would be the better option.

Suggesting that I change my clients' workflow before they've even become my clients is... not likely.

I've had to do it. Up to you.

Joe, I know this is similar to your other audio sync thread. It does sound like Resolve is not up to the task. I wonder if there is a third-party product such as PluralEyes that could help? Too bad (unless the Multicam sync can be used to overcome this issue - I doubt it, though).

Add - I just watched your video for this issue. I don't believe Resolve has the ability to perform this task (I'm not sure why, though). I would try asking the community experts how they would accomplish the task you are attempting. Maybe someone here has a workflow suggestion, for example (or can recommend a third-party tool to help).

Hi Steve
Thanks for your reply! I actually am a PluralEyes user from way back.
By submitting reports here I'm mostly trying to make Resolve a better program for all of us. I've (currently) chosen it as my platform of choice and, before I decide to revisit that decision, I want to do my part to try and smooth out the places where it's not up to the task.

So usually I'm not asking for workarounds but rather reporting bugs or what I see as deficiencies.

Cheers!

I get that from reading your posts, Joe. Seems reasonable. Would be great if Resolve could perform this sort of task, but it looks like it can't at the moment. It is definitely a worthwhile feature request, though.

Cheers

[Shrinivas Ramani]

Hi Joe

We found and fixed an issue described in the first post. Please give 18.0 beta 4 a try.

Thanks
Shrinivas

If that's so then it's broken and should be fixed.

How would you fix it? What I've found is that if I've got a couple of goes at a piece to camera, where the start has got the same kind of intonation and pacing, Resolve will sometimes grab "the wrong one" to sync to, especially if both cameras don't have all the same takes. One way I've got around that is to just chop out a "matching set" of takes to pick the best one, and match that, and it mostly works.

Perhaps some sort of dropdown where it finds a couple of likely candidates for matches and leaves it up to you to finally pull the trigger on it would be good? Like "It might match here, here, or here, you choose!" kind of thing. I guess if you're doing a lot of multicamera stuff you'd either get your workflow right from the start so audio sync could work, or you'd get everything on timecode sync.

If that's so then it's broken and should be fixed.

How would you fix it? What I've found is that if I've got a couple of goes at a piece to camera, where the start has got the same kind of intonation and pacing, Resolve will sometimes grab "the wrong one" to sync to, especially if both cameras don't have all the same takes.

Hi Gordon
Thanks for replying. I agree that, when there are very similar-sounding takes, your narrowing-down strategies are good ways to make it more likely that Resolve will sync the correct take. However this isn't the situation I'm in.

My project is quite professionally slated. While they didn't use timecode, they did slate well, including audio slating, and the quality of both the camera and second system sound are good. It's not hard to hear when things are correctly - or incorrectly - synced. When Resolve syncs the wrong audio - often by syncing several non-matching audio takes to one picture take - it sounds like a cacophony of voices slating at the same time.

I get that the situation you're describing might be hard to fix because it's fundamentally hard to discern between similar takes. This is not the case here. So how to fix it? Fix the issues in the code that are making it false-positive and sometimes false-negative.

Hi Joe

We found and fixed an issue described in the first post. Please give 18.0 beta 4 a try.

Thanks
Shrinivas

Hi Shrinivas
Thanks for replying. So glad you're working on it!
I did retry syncing in beta 4 (build 23). I synced day 1 reel 1 - 43 clips. 14 of them (33%) were improperly synced.
Most of those synced the proper clip but also synced one or more additional clips.
When I tried to resync most of them with just the clip they corresponded to they synced correctly.
A few when I tried to resync with the correct clip still wouldn't sync. I tried again and, for some reason, they started syncing. Perhaps an initialized variable floating around that causes this last unstable result?

I'm psyched that you fixed the bug that was causing the three files I sent along to incorrectly sync.

I just uploaded proxified versions of all of day1 reel1 along with a project that shows the many files I'm still seeing incorrectly sync. Hoping that if you get that case to work correctly it'll zap the remaining bugs!

Here's just the project. I'll PM the actual media so as not to share too much of my client's work with the world at large!

https://drive.google.com/file/d/1x23fvV ... sp=sharing

[Shrinivas Ramani]

Hi Joe

Can you check with Resolve 18 beta 6?

Thanks
Shrinivas

Absolutely!


Sent from my iPhone using Tapatalk

18b6 does MUCH better syncing my project.

Of 65 takes from Day 1 it improperly matched only 6 of them.
Since they're all clearly voice slated I think there's still a lingering bug - but this is WAAAAY better than before.
I'll submit proxified versions of the remaining 6 takes as repro cases for the remaining issue(s).

Turns out the same media files will do.
Attached find the drp that shows the clips that sync improperly.