You can use proxy files to sync audio in Final Cut Pro X

Here’s a discovery I made today: if you’re working with an assistant editor, you can send a bunch of proxy files to the assistant, have them sync audio with the proxy files, and then when you get the files back, you can merge them into your event and they will connect to the high-res files. It’s pretty slick, and obviates the need to send out original or ProRes media. The proxy media that Final Cut Pro X creates is a 1/4 size version of the ProRes media, and it’s so good that I’m hard-pressed to tell the difference between original and proxy in the Viewer while I’m editing. Of course, if you play back full screen, you see the jaggies.

NOTE: I’m using DualEyes for the audio syncing, since PluralEyes doesn’t yet have a FCPX version. And FCPX’s built-in synchronize clip feature only works when you know which two clips to sync – so you need DualEyes if you’re batch-processing large numbers of clips at a time.

Here’s the workflow:

1. Create an event (Opt-n) and import some video and audio into it (cmd-shift-i). On the import dialog box, make sure you place a check next to “Create proxy media.” Wait until the proxy files have been created. Quit FCPX.

2. Now we have to do some work in the finder: make sure you have the external hard drive mounted that you want to copy the event onto, which you’ll be passing to the assistant or taking away to work on yourself. Also make sure it has a folder called Final Cut Events in the root. Then navigate to your Final Cut Events folder (in your Movies folder if you’re working off local hard drive, or in root level of an external drive). Find your event folder. Copy the folder and all subfolders EXCEPT one: don’t copy the Render files folder, and deselect all the video files in the Original Media folder, so that you copy only the original audio files. The whole point of proxy media is to save space and time, so you don’t want the hi-res files leaving your primary storage.

3. When the assistant gets the drive and opens FCPX, there will be a red alert displaying in the event, warning that the footage is offline. Don’t panic. Just press cmd-, or open preferences from the Final Cut Pro menu. Under Playback, select “use proxy media.” Now, everything is groovy: the proxy footage shows up, and your assistant can get to work, as follows.

4. Quit FCPX. In DualEyes, create a new project. Select the video files located on the Transcoded Meda > Proxy Media folder. Add the audio files located in Original Media. Run the sync (I always run with “try really hard” selected, because it always works better and is worth the extra waiting time). Files that match the length of your video clips will be added to the Proxy Media folder. Also a temp folder created by DualEyes. When the batch is finished, delete the temp folder, and move the new audio files over to the Original Media folder.

5. Now open FCPX. You’ll find all the new audio files added to your project. These will be named with both the video and audio clip they are associated with, so that you can tell immediately which file to synchronize by its name. Cmd-click on the video and the audio file to select both, then press opt-shift-G to synchronize the clips. FCPX creates a synchronized clip for each. At this point, the assistant can add keywords, create smart collections, and do whatever work is necessary on the files to send them back to the main project.

6. To bring the event back in, connect the external hard drive to your home system. Remove the event on the home system from the Final Cut Events folder, but don’t throw it away yet. Place the event coming from the assistant into the Final Cut Events Folder in its place (Final Cut should be closed while you do this). Grab the original media (or references to the original media) from the Original Media folder that you’ve parked on the home system, and move it to the Original Media folder on the incoming event. You can now throw away the old event, because the one from the assistant will replace it.

7. Start FCPX. Everything should read-in normally, and you’re good to go: the original files will now be used (provided the “use original or optimized media” is selected on the home system’s FCPX preferences).

It’s important to remember that in FCPX, you can’t modify the original media (or any other media, for that matter) outside of FCPX. It will render the media permanently offline inside of FCPX if you do, and you’ll have to re-import it. This is a problem that I hope is fixed in future versions.

8 thoughts on “You can use proxy files to sync audio in Final Cut Pro X

  1. Shane

    Hi Dan, great blog!

    I’m contemplating taking copies of my (so far) 20 or so hours of feature documentary interview footage on an external FW800 HDD while I’m out of the country for several months and keywording it on my MBPro.

    What I wanted to know was:
    1. Should I connect up the original footage (in all it’s various flavours) into one event, or into events for each shoot day/interview as you’ve suggested above? How would I undertake my future edit if they’re all split up?
    2. Should I (instead of copying the original media on to my travel drive to take with me) use FCPX to create PROXY media files to take with me and leave the original media stored at home and giving me more room on my travel drive?
    3. If I spend days keywording Proxy files, will those keywords “re-apply” or “carryover” to the original media when I eventually reconnect it all up? If so, how? Are you sure? It would be soul crushing to have to do it again..

    I had been using extended markers in FCP7 to keyword sections of takes on a couple of the them and am resigned to having to re-do them, but I want to make sure I’m approaching this the right way going forwards – especially as there is a lot more to come!

    Appreciate your advice! 🙂


    1. Dan McComb

      Hi Shane,
      Spending a couple months carefully key wording your events is a fantastic way to set yourself up for a smooth edit. Regarding your first question, you will definitely want to create separate events for each of your shoot days, people interviewed, or whatever makes sense. In my case, I organized events by shoot – as in some cases, we had more than one shoot per day. So if we had three shoots, I made three individual events. It’s very important to break these up, because FCPX loads events into ram, and if you have events that are too large, it will slow everything down. You only want to load as many events as you’re working on at the same time to keep things running snappy in FCPX.

      Regarding 2, I would definitely make proxy media to take with you, and leave the full-size stuff at home. You can hardly tell the difference in resolution on a laptop. Proxy is a great way to go.

      Re: 3: One of the truly beautiful things about FCPX is how seamlessly Apple has integrated proxy media into the workflow. All you have to do once you’ve made proxy media, to output fullrez, is just press cmd-, for preferences, and then from Playback, select “Use Original or Optimzed Media.” Done. You won’t lose anything. But don’t take my word for it – do a test on a single event before you hit the road, add a few keywords, and then bring it back. That will give you the confidence you need to worry about which keywords to apply, rather than whether your work will disappear when you get home.

  2. Shane

    Hey Dan,

    That does indeed seem to be the way to go, thanks for the tip!
    The media reconnected flawlessly in my test, but then I also realised that I will be cutting with the Proxy files anyway so even if the keywords didn’t stamp back on to the original media as such it was redundant by that stage anyway as the cut would be done and it would only be exported for onlining.

    One thing I noticed is that FCPX only likes one instance of the event to be mounted at a time. So my original media (on my G-SAFE RAID) has the final cut events folder on it, I then create proxies in FCPX which it stores on the GSAFE and I then copy the whole folder structure to my G-Drive for travelling (except for the contents of the ‘original media’ folder – though this doesn’t seem to matter because they are only aliases anyway and thus only a few kb), I connect the G-Drive, switch to ‘using proxy files’ and can keyword away to my heart’s content and it’s all good when I reconnect.

    The only extra step for me is that I need to then go back and delete the Proxy media originally created on my G-SAFE to save space, and just keep the copied ones on the portable G-Drive.

    In FCPX therefore I just ned to switch between working with proxies or original media in the prefs – depending on which drive is mounted.

    Eventually (when it’s time to edit) I’ll just copy them back to the same drive as the original media (probably a new larger storage solution) so it’s all in one place, but this should work well for now.

    – When I do that, what other files need to go back too? Is it just the proxy files themselves or are the keywords somewhere else? Where are the keywords ‘stored’ exactly, do you know?

    1. Dan McComb

      That workflow should work fine for you.

      When you are done with everything on the portable and want to bring everything back home, the file that contains all your keywords and other organizing work is located in the following location:

      Final Cut Events > [your event name] > CurrentVersion.fcpevent.

      For projects, all of your work is located in:

      Final Cut Projects > [your project name] > CurrentVersion.fcpproject.

      Just be sure to grab those two files and replace the ones on your home drive (with FCPX turned off), remove your portable drive, then start FCPX. Boom, your work is all on the new drive.

      One thing to note: You mentioned FCPX does not like two events with same name and properties on two drives mounted at same time. That’s correct. But you can solve this problem by creating a temporary offline place to store projects you don’t want open on all of your drives. I create a folder called “Final Cut Events Parked” and that way it sorts right next to the Final Cut Events folder in the finder, so I can find it easily when I want to enabled an event. Same for projects. Placing your events or projects into any place other than the default locations (i.e., the folder named Final Cut Events or Final Cut Projects at the root of your drive) will hide it from FCPX. Make sure you have FCPX turned off during any moves of this kind to avoid confusing it.


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