How to sync video and audio in davinci resolve

Andy Mees wrote:For the sake of discussion Tom, how does this differentiate from, say, using a Compound Clip to do the same thing?

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• Video and Audio Sync Not Working
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• How do I fix audio and out of sync DaVinci Resolve?
• How do I sync audio and video?

Speaking personally, I actually do use nested containers for this at the moment. I chose Timelines rather than compound clips.

In my current online theatre project I had:
- Nine actors, each recording video from their own webcams, using OBS to record, making one video per scene. Video files were 5 - 20 minutes in length.
- Audio recording to WAV was done using Audacity (or similar tool), with one long recording per actor per session (containing many scenes). The actor would start the recording at the start of the session, and let it run throughout. Audio files were therefore 1-3 hours in length.
- Video files had 'in-camera' audio, but in most cases it was AAC rather than WAV (due to a limitation with OBS' encoders). As I wasn't expecting to use this audio, I didn't provide instructions for setting up OBS audio properly, and for most of the actors the OBS audio ended up clipping. It was usable for rough sync, but not for the final edit.
- Also, due to OBS latency, all of the in-video audio was fractionally out of sync with the video, so even in the few cases where it was WAV and had suitable levels, it still needed to be adjusted. And for some of the actors, OBS dropped frames due to inadequate hardware, meaning the audio drifted further out of sync throughout the recording, requiring periodic manual corrections; something I hadn't anticipated during recording.

Here's an example of the files for one actor on one day:

Because the audio files were much longer than the video files, containing audio for multiple videos, Auto Sync Audio was not an option for me at all. I hoped that a Waveform match might correctly find the right part of the long audio file and append just that part to the video, but it never did. It always failed, with no feedback.

So instead I made one Timeline per actor per session, in which I laid out the long audio track against the multiple videos, broke it into sections of the same length as the video files, then used the Edit page "Align Clips -> Based on Waveform" to get a rough sync, then did the final sync using claps made by the actors.

Then I muted the in-camera audio track and used these Timelines in place of the original media files. Specifically, I then added them to Multicam Clips, syncing the audio and video from multiple actors such that I had one Multicam per session, and could then use the Multicam workflow to switch between the actors and their audio.

This mostly worked OK. But I did face the following issues:
1. Take Selector does not work with nested containers.
2. I was using an extra level of nesting, which I believe contributes to the stuttering/out-of-sync audio issues when Delivering.
3. Resolve does not cache waveforms for nested containers. So every time I opened every timeline, I had to wait multiple seconds or even a minute for the waveforms to appear.
4. To avoid these issues I would have to decompose the timelines to the original clips, but doing so made it much more tedious to fix any sync issues I found later during editing (eg where dropped frames caused audio to drift out of sync late in a clip). Where I had decomposed the timelines, I now had to fix sync in multiple individual clips at once, rather than just fixing it once in the source and having all clips automatically reflect this.

It did mostly work OK, so yes in my case nested containers was viable. I didn't face issues with timecode because I didn't use it, nor did I need to access multiple audio tracks per video file like others do.

But it would still have been easier if I'd been able to make use of 'proper' audio syncing, where all I needed to do was drag video files and I instantly received both my in-camera and external synced audio.

And like Lee says, when you use workarounds like this in Resolve, you very frequently hit "it ALMOST works..!" situations. There are so many edge cases, like Take Selector not working properly with nested containers.

Of course it would also be great for nested containers to be improved such that these edge cases don't exist. I've said many times that I wish that I could always throw a Timeline or Compound Clip anywhere I could put a media file and know that it would work identically. But I (and many others) have already made feature requests for those improvements, so this one is aimed at a different area

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Video and Audio Sync Not Working

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Hello

The usual way that I sync video with audio recorded onto a zoom is by going into the Media tab - selecting the video clip and getting it to the point where the clapper comes down, keeping the Waveform tab open, selecting the audio clip that I want, getting that to the point where the clapper board comes down, then select the link/unlink audio button. What this usually does is it syncs up the sound and replaces the original video sound with the external sound file.

However - today it's not doing that. It's syncing them up but all I can hear is the video sound which usually goes away and is replaced but this time is not. I have 156 clips to synch up.

HELP!!!

UPDATE:

I fixed this by doing exactly as I did above (which is also in DR's manual) but instead of pressing "link" once, I pressed it so that it was linked, then pressed it again so that it was unlinked, then pressed it again to link. This solved the issue and replaced the video sound with external sound. All clips now linked.

Brad Hurley

• Posts: 1949
• Joined: Wed Jan 17, 2018 7:42 pm
• Location: Montréal

Okay, but there's a much easier way, which is to select the files you want to sync, right click, and choose the auto-sync by waveform (and there's an option you can tick to replace the camera audio with the externally recorded audio). That's described in the manual as well. When using a clapper I've had 100% success on hundreds of clips by using auto-sync by waveform.

Resolve 17 Studio, Mac Pro 3.0 GHz 8-core, 32 gigs RAM, dual AMD D700 GPU.
Audio I/O: Sound Devices USBPre-2

tikiedit

• Posts: 6
• Joined: Sun Mar 17, 2019 12:17 am
• Real Name: Nelson Torres

Thanks for the tip! Suffered through the same issue. Had to manually sync all the footage as well because A) sound files & picture's time of day timecode weren't synced (cam & sound were off by a day and some hours - God forbid camera & sound should check to make sure their units are set up correctly) and B) the sound waveforms were recorded so low that Resolve couldn't read them for auto sync.

moved to the Resolve forum

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How do I fix audio and out of sync DaVinci Resolve?

How do I sync audio and video?