Perfect Syncmap Sync
Using timecode on set is a great start to synchronizing your audio and video. But here's the thing: it's almost never perfect right out of the gate.
To get everything flawlessly aligned, you need to use some manual tricks, like creating a time-of-day syncmap. This process (similar to Avid's "auto sequence") maps out when the camera was recording and when it was off. By laying this out on a timeline, we can visually line up our audio and video, and then take advantage of a powerful feature introduced in DaVinci Resolve 20.1: auto-syncing based on manual IN points.
You can choose to sync on the timeline with audio waveforms, insert with timecode, or any visual cue you can find to align the clips. I love the “B” and “P” trick for syncronizing lip movement for speech.
Here is how to create a robust synced master clip that lives inside your Media Pool.
Prep Your Media Pool
To set yourself up for success, your Media Pool needs to be organized.
Place your video clips and your externally recorded audio clips into the exact same bin.
Set up your custom bin columns. Right-click the column headers and ensure you have Synced Audio, Start Timecode, and In visible.
Crucial Step: Select all your clips and hit Option + X to clear any existing IN and OUT marks. If you don't clear these marks, DaVinci Resolve will only edit portions of your clips to the timeline.
Build Your Timeline Sync Map
Now, let's get a bird's-eye view of your entire shoot day.
Create a new timeline and name it "Sync Map". Ensure your audio track type is set to Mono, as this is standard for dual system iso sync sound.
Select all your video clips in the Media Pool, right-click, and choose "Insert selected clips to timeline using timecode". This drops all your video clips onto the timeline so that the source timecode matches the timeline timecode exactly.
To keep things clean, delete the scratch audio attached to your video clips. Select the audio and press Option + Delete to remove it without unlinking or deleting the video.
Finally, select all your external audio clips in the Media Pool, ensure your blue track destination header is set to A1, and insert them to the timeline using timecode.
Find and Fix the Offset
Why didn't we just auto-sync in the Media Pool? Because timecode isn't always frame-accurate.
Zoom in on the first clip where the slate closes. You will likely notice that the sound of the clap happens a frame or two before the slate visually closes.
To fix this offset, lasso your audio clips on the timeline to select them.
Use the period key (.) to nudge the audio forward one frame at a time until the sharp transient of the clap perfectly matches the visual impact of the slate.
Auto-Sync with IN Points
Now that your timeline is perfectly synced, we need to bake this sync into the master clips in the Media Pool without destroying any metadata. I think of this as gluing it together with the original film.
Pro-Tip: Set up keyboard shortcuts to make this fast. Assign Ctrl + S to "Auto Sync Audio" and Option + F to "Find in Media Pool".
Make sure you are in dual viewer mode.
Park your timeline playhead on the very first frame of your video clip.
Press F to "Match Frame" (loading it into the source monitor), then press I to mark an IN point. Press Option + F to highlight this clip in the Media Pool.
Next, select the nudged audio clip directly below it on the timeline. Press F to Match Frame, then I to set an IN point.
Go to your Media Pool and Command + Click the video clip so both the audio and video files are selected.
Press Ctrl + S (Auto Sync), choose "Synchronize using In," and make sure to keep video metadata.
You will now see your external audio listed in the "Synced Audio" column in the Media Pool.
Rinse and repeat this match-frame process for the rest of the clips on your timeline.
It’s worth noting this method allows for multiple external audio sources to auto sync to a video clip, making it very power especially when several external audio recorders are used on set.
Why Use This Method?
You might be wondering, "Why not just change the timecode offset in the clip attributes?".
If you manually change a clip's timecode offset, that modification is only valid inside that specific DaVinci Resolve project. If you ever need to send those files to another editor or into different software, the media will show up offline. By creating a sync map and syncing by IN points, you establish perfect synchronization without destructively altering the source clip metadata.
