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I've been working on a feature film shot on the ARRI Alexa and Alexa Mini and had to come up with a workflow for syncing and rendering out dailies. DaVinci Resolve 12 proved useful because all of the prep work could be done in one application all at once, with the added bonus of being able to roundtrip again after picture lock.
I used our very own Auto Transfer tool to offload the memory cards to two hard drives at once with checksum authentication to ensure the copies were identical to the source files. The media files were then backed up to LTO tape at the end of the day.
In Resolve 12, create a new project, then go to File > Project Settings and switch off Use local version for new clips in timeline from the Color page. This will be important later on.
Then bring the video and audio files into your Media Pool and organize them in whatever manner makes sense to you. I chose to create bins for each scene (be careful what names you choose for the bins).
On this particular movie no audio was shot in-camera so the only way to automatically sync audio and video is by timecode. Select the video and audio files in your bin, right-click and choose Auto-sync Audio Based on Timecode.
In theory this is all you should need to do to get perfect sync, but in practice timecode can drift or it may be set incorrectly (or not at all) in the camera or sound recorder.
An additional reason for splitting things into bins is because if you are shooting time-of-day timecode, you may have multiple clips with the same timecode that could confuse Resolve and cause it to sync clips up to audio from a different scene.
In the event that the audio is not synced correctly, open the video in the viewer, scrub to the exact frame that the slate hits on and write down the timecode for that frame. Then open up the audio file and stop it on the exact frame that you hear the clap of the slate (in a lot of cases this will be an obvious short spike in the waveform towards the beginning of the file). Then right-click the audio file in the Media Pool and select Clip Attributes. In the Timecode pane, enter the timecode from the video you noted down earlier. Then repeat the earlier step of selecting the video and audio files, right-clicking and choosing Auto-sync Audio Based On Timecode again.
(If you can't hear the slate, go to the Audio pane of Clip Attributes and make sure your extra audio channels aren't muted.)
This will modify the timecode of the audio file so it can then be matched up automatically. You may be wondering why automatic matching is so important when you could just manually sync clips in a sequence. There is an important reason for this that will be clear later on.
Now select all the video clips then right-click and select Create Timeline Using Selected Clips.
Open the timeline then switch to the Color tab and grade the clips as you normally would.
In the Deliver tab, choose the Individual source clips option under Render timeline as and Use source filename under Save as. This will export each clip in the sequence as an individual movie file with the same filename as its original source file - this is important to make it easy to reconnect back to the high-res source files later. Because these are offline clips we're rendering as ProRes Proxy to keep file sizes small but keeping the resolution the same as the source files.
This is why it was necessary to auto-sync the clips in the earlier step. I could find no way to manually sync audio clips and then link the audio back to the original source file. That synchronization will only exist in the sequence itself and is ignored if you choose the Individual Source Clips option.
Mark in and out points on the timeline at the bottom of the Deliver page to make sure it's going to render out all of the clips, then click Add to Queue. It's easiest to queue up lots of sequences and render them all out in one go.
Import the rendered proxy files into the NLE of your choice and edit.
After editorial, export an XML from your NLE and reimport back into your Resolve project. (With Avid you need to export an AAF and things become a bit more complicated but this is covered in the user manual.)
On the Load XML dialog, deselect Automatically import clips into media pool (because they already exist in the media pool) and deselect Use color information if you edited in FCPX. Then click Ok.
Resolve should present you with a timeline from your NLE, however often things will not translate fully and need to be fixed. A great way to do this is to render out the full sequence from your NLE and then navigate to it in the media pool's browser. Right-click the file and select Add as Offline Reference Clip. Then right-click the timeline in the media pool window and select Timelines > Link Offline Reference Clip and choose the clip you just added.
Switch to the Edit pane and click the icon that looks like a filmstrip underneath the left-hand viewer. Choose Offline and Resolve will show the file you rendered from your NLE. You can then scrub through or play your timeline and it will show the reference clip alongside the corresponding frame of your timeline so you can compare them.
If any clips are offline you can right-click the timeline in the browser and select Timelines > Reconform from Bin(s), then select the bins with your source media. If the clips still won't reconnect, select the relevant clip in the media pool then right-click the offline clip in the timeline and choose Force Conform with Selected Media Pool Clip.
(At this point you may want to media-manage the timeline onto another drive to save disk space but I opted not to.)
Now go to the Color tab. If you don't see the grades you did previously, select all of the clips (you may need to click the Clips button at the top to see them) then right-click and choose Use Remote Grades (you may need to right-click again and choose Update All Thumbnails to see the changes).
Because you switched off local grades by default at the start of the project your grades were remote, which means they will stick across different timelines and if you adjust the grade of a clip, any other copies of it on your timeline (and throughout the project) will also be updated. In some cases this may not be desired, so you can right-click and choose Copy Remote Grades to Local so that your changes only apply to that specific instance of the clip.
After grading you'll probably need to send it back to your NLE again for titling and syncing with the finished audio. You can do this one of two ways: export each clip individually like in Step 4 and then reconnect in your NLE (media managing before doing so will help a lot) or render out a single QuickTime file of the entire timeline. If you don't expect many editorial changes at this point the latter is simpler, which is what I opted for.
What was your rendering speed? I know this is depending on your system configuration but I would like to have an idea.
Also is copying clips with auto transfer to two different hard drives at once, slower than copying to one drive?
I don't remember exactly but it was above realtime on a 4-year-old laptop.
Yes, copying to more than one drive is slower. I like to have two copies immediately just in case but an alternative workflow would be to copy to one drive and clone it later.
Thanks so much for this writeup! I work with AVID and Resolve and just employed this same workflow on a set where I was the DIT, Editor and Colorist. It was mostly a complete success except when it came time for the mix.
When syncing in DaVinci Resolve, the audio on the rendered out synced dailies ends up with the same name as the video. In Resolve, the video clip also inherits the scene and take metadata, but that doesn't seem to make it into Avid when importing the AAF for each reel. During the mix, sometimes they need to go back and reference the original audio clips, but there doesn't seem to be a way for them to figure out which audio clips synced with each video clip.
Have you run into this issue? Do you have any workflow suggestions for how to solve it?
For this workflow Adobe Premiere was used for editorial. The majority of scenes had 3 or fewer audio tracks so it was deemed simpler to just bring all the channels into editorial instead of mixing down. Obviously if you have more channels than that it could get unwieldy.
But the timecode on the original audio files should be the same as the video so it should be easy to sync back up again. You can use Resolve as a reference to determine the original filenames.