I would love to be able to quickly, accurately, and automatically create a multicam clip from however-many such files, without requiring manual adjustment or audio synchronization. Seems to me that this should be (and perhaps is) possible, but I haven't been able to make it happen. Ideas?
To my knowledge that cannot be done using either FCP or Resolve. It's just not a frequent post production procedure to sync and arrange a multicam based on time values embedded in the filename.
However the situation sometimes arises and there are 3rd-party utilities that can read the filename and update the file creation date based on that. If you did that in theory FCP could create and sync the multicam using the file creation date. I don't know if that would be sub-second accuracy.
There might be a utility that could read the filename and update the actual clip timecode metadata (not just file creation date). But I'm not aware of one. It should be possible to write an AWK script that extracts the date/time value from the filename and passes that to ExifTool or similar which updates the timecode metadata.
In general the best procedure is plan ahead for multicam sync. That might include putting a Tentacle Sync device on each camera. That records audio LTC timecode on half of one channel. In that case you'd use their Tentacle Desktop utility to scan the offloaded camera files and produce an XML for FCP that syncs them: tentaclesync.com/sync-e
Or sometimes you can set the cameras to "free run" timecode and simultaneously reset all cameras via IR command or hitting a camera button if there's just 3-4 of them. Afterward they will typically stay in sync for a few hours. In FCP or other NLE you can then sync based on timecode. Dave Dugdale described the procedure in this video:
For our Sony FX6 cameras we briefly jam-sync those via SDI cable from the Sound Devices audio recorder. After that the cable is unplugged and they will stay in sync all day since they have low-drift timebases. In FCP or Resolve we sync those clips based on timecode (meaning metadata timecode embedded in the file).
Both sync methods can be combined. E.g, on a big multicam event shoot, cameras with timecode can be jam synced, then the non-timecode cameras could have Tentacle. All the Tentacles would need to be jam-synced from the timecode master (Sound Devices recorder in this case). That uses a cable like this: www.bhphotovideo.com/c/product/1327595-R...ble_tentacle_to.html
The camera files with Tentacle can be read using the free version of Resolve and the embedded timecode metadata updated based on the audio LTC timecode. Then those files could all be synced in FCP based on timecode. The procedure is shown at 21:00 into this video "The History and Science of Timecode":
...I am working almost exclusively with footage recorded by others, most often police body-worn camera video. I have no control over filming.
If that is a long-term engagement or a frequent task, you should probably investigate with other large-scale reality productions about how they manage that. It has nothing to do with FCP in particular -- to my knowledge no NLE can read date/time info from filenames and sync multicam based on that.
A first step is investigate how closely the action cam file creation date/time matches the embedded date/time in the filename. If the filename is simply duplicating the creation date/time in a different form, FCP or other NLEs can sync based on file creation date aka file timestamp. However that assumes the timestamp is accurate and consistent across cameras, which it is often not.
It's common for each camera to be set to a different time. E.g, one might be on daylight savings time and the others not. Or some were just never set correctly. In that case you can sometimes batch update the date/time in FCP after import by selecting all clips from a given camera, then Modify>Adjust Content Created Date and Time.
To make that (or any other multicam operation) work well, the files from each camera should also be labeled or have filenames unique to that camera. On my doc team we offload each camera to a specific unique folder name, usually consisting of camera type plus operator or camera type plus location: e.g, GoPro_6_JohnSmith or A6600_LivingRoom. Then we use the FCP import options Preferences>Import>Keywords: From Folders. Each imported file is automatically keyworded with the designated unique camera identifier.
That facilitates selecting all files from a given camera for labeling. Each group of files from a given camera must be labeled with a camera name or angle name in FCP in the Inspector>General View. As part of that labeling, the file date/time of all clips from a given camera can be updated. That works because usually all files from a given camera are off by the same amount, e.g, +1 hr, or -12 minutes, etc.
If the file timestamp has no relationship to the embedded date/time in the filename, you can probably use the previously-listed Mac tool "A Better Finder Attributes" to read embedded date/time from filenames and tweak file creation dates (aka timestamps) based on that. See under the heading: Using Dates Embedded in the File Name at this web site: www.publicspace.net/ABetterFinderAttributes/index.html
That's a step in the right direction, but might not be sufficient. What you ideally want is a utility that reads the embedded date/time info from the filename and updates the actual SMPTE timecode of each clip. That would enable creating and syncing a multicam based on timecode. All NLEs support sync by timecode. I don't know of a single utility that does that, so you'd have to investigate.