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Syncing Audio

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Glenn Payne
Syncing Audio
on Jan 21, 2018 at 3:47:24 pm

Hey guys,
I'm about to begin editing on my new feature film with fcpx. We shot in Pro Res 444 4k. For previous projects I've used the audio syncing option built into fcpx and I've loved it. The problem is that it seems to create a brand new file each time is syncs and with this footage being 4k I don't have the storage space to duplicate it all while keeping the originals.

A friend suggested plural eyes (which I've toyed with briefly in the past). Would you guys suggest going that direction and if so, does footage cut okay when using plural eyes. My concern is that if it syncs the audio for me without permanently attaching it (via a newly created file) will the synced audio stay with each portion of the clip once I start cutting and moving it around in pieces or will it just stay connected to the very beginning of the clip, with the audio clip to the right of the cut point just left floating there not attached to any video clip?

thanks for any advice!
Glenn


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Jeremy Garchow
Re: Syncing Audio
on Jan 21, 2018 at 5:32:37 pm

Does the audio and video have matching tc?

If so, I'd suggest Sync-N-Link X which gives you options on how to deal with the clips: https://intelligentassistance.com/sync-n-lnk-x.html

I like to make new clips that are trimmed to the length of the video (instead of the audio, like FCPX). It also gives you options with naming and Role assignment.

Jeremy


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Glenn Payne
Re: Syncing Audio
on Jan 22, 2018 at 7:41:51 pm

Thanks for the info, Jeremy!

We do have matching tc. I'm not familiar with Sync-N-Link X, but I'll definitely check it out. Does it duplicate clips or just sync the two and leave the files as is?

gp


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Glenn Payne
Re: Syncing Audio
on Jan 22, 2018 at 7:50:03 pm

I stand corrected, we did not have synced time codes. they tried to get it synced but kept having a technical error so we just have standard slating.


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Jeremy Garchow
Re: Syncing Audio
on Jan 22, 2018 at 8:07:05 pm

If you need to sync by waveform, then Plural eyes would be the way to go.

Sync-n-link puts new copies of the footage in the library. I usually do the syncing in one library and transfer the sync’d clips to the main library.


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Joe Marler
Re: Syncing Audio
on Jan 22, 2018 at 9:08:36 pm

[Glenn Payne] "...For previous projects I've used the audio syncing option built into fcpx and I've loved it. The problem is that it seems to create a brand new file each time is syncs and with this footage being 4k I don't have the storage space to duplicate it all while keeping the originals...A friend suggested plural eyes (which I've toyed with briefly in the past). Would you guys suggest going that direction..."

FCPX does create optimized media when you create a multicam clip (which takes considerable space if the originals are H264) -- but only if this option is selected in FCP preferences>playback. Depending on your machine and whether you're using proxies, this may not be needed. I personally never use it.

If your material is 4k H264 you'll normally need proxies for smooth multicam editing. If proxies are available you don't need optimized media for multicam so you can turn off that option in FCPX preferences. That solves your space problem.

If FCPX audio sync is sufficient, I recommend that over Plural Eyes. Provided you tag the name or angle of each batch of camera or recorder clips in the Inspector metadata, FCPX sync by audio usually works pretty well.

Plural Eyes is more capable from a pure syncing standpoint and can do drift correction on long takes. However it is not optimally designed for FCPX workflow. You must either import and sync everything in Plural Eyes, then export to FCPX, otherwise you can only sync by putting "tracks" of connected clips on the timeline and round tripping to Plural Eyes. You cannot export clips from the Event Browser to Plural Eyes, and you cannot export a non-synced multicam clip from the Event Browser to Plural Eyes.

I think Red Giant could make Plural Eyes more compatible with FCPX workflow but they focus on all the other track-oriented NLEs.

The sync algorithms in Plural Eyes are very sophisticated and it can search through hundreds of files looking for a waveform match. So in difficult cases it can come in handy.


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Glenn Payne
Re: Syncing Audio
on Jan 23, 2018 at 4:44:45 am

I've used the multi-cam function for other projects, but this one is single cam. I hear mixed thoughts on proxy versus editing the straight footage. I'm always up for getting new opinions on it. We shot in Prores 444 4k. If it's possible to use the built-in syncing option in fcpx and not have it create a brand new clip (for storage space purposes) I'd absolutely love that. I'll do some tests tomorrow and see how it looks.

That would be great news though!


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Joe Marler
Re: Syncing Audio
on Jan 23, 2018 at 12:27:04 pm

[Glenn Payne] "I've used the multi-cam function for other projects, but this one is single cam...

Even for single-cam projects with external audio Sam Mestman recommends building it as multicam:

http://www.fcpworks.com/sync-or-multicam-clips/

[Glenn Payne] ...I hear mixed thoughts on proxy versus editing the straight footage. I'm always up for getting new opinions on it. We shot in Prores 444 4k.

If you shot in ProRes 444 4k, you can probably edit that directly without proxies, and without optimized media for multicam. In my testing, if the source media is ProRes 444, FCPX does not create optimized media -- even *if* FCPX preferences>Playback>"Create optimized media for multicam clips" is enabled. It's smart enough to know it's already optimized. So if all your material is ProRes 444, you should never have seen additional space consumption when creating a multicam clip. But if you want to be sure you can turn off that preference.

[Glenn Payne] "...If it's possible to use the built-in syncing option in fcpx and not have it create a brand new clip (for storage space purposes) I'd absolutely love that..."

For ProRes 444 it should never create a new clip on disk when creating or syncing a multicam clip. If any clip in the MC is not ProRes it will create disk-based optimized media, but ONLY if the above option is on. It does create a new multicam clip in the event browser but (if the above option is off or if all your media is ProRes) these are simply links to the original media. No new physical file is created on disk.

You can also save space by turning off background rendering, which is in FCPX preferences>playback>Background render. On a contemporary machine you generally don't need that for most codecs, and certainly not for ProRes.

The main issues for effective synchronization of external audio in FCPX are:

(1) Use multicam not sync clips (even for single camera)

(2) Before creating multicam, ensure all video and audio are labeled properly in the Inspector. The below video is old but the basic principle still applies even on 10.4. If your cameras and recorders do not emit name/angle metadata which FCPX can import, each batch of clips from a camera or recorder must be labeled in the Inspector with a camera name or angle name. Without this the multicam sync will not be reliable.

Batch renaming and multicam sync (10.0.6 but the part about labeling camera name or angle still applies):






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Glenn Payne
Re: Syncing Audio
on Jan 23, 2018 at 4:24:47 pm

That's excellent info, Joe! Thanks for much for taking the time to respond. I'm about to watch the video you sent. That's really interesting about using the multi-cam option for a single camera sync over the normal sync option. I'll give it a shot.

Thanks!

Glenn


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Glenn Payne
Re: Syncing Audio
on Jan 23, 2018 at 9:53:25 pm

I think I'm about ready to dive into the edit. At present, my plan is to use the multicam option to sync each individual piece of video with each individual piece of audio, while unchecking the box that says to create optimized media for multicam clips.

The footage is prores 4444 so under the rendering option I'll select the 4444 setting and cut the footage as is, with no proxy or created optimized files. Does this sound workable to you guys??

I've discovered a new problem that makes my stomach turn. My team was running the mixer's scratch track into the camera but occasionally they'd lose the feed. The film takes place in a car so the various mics were inside the vehicle with the actors. The camera was outside the car at times depending on the shot. So if we lost audio to the camera or were recording basically no sound on the outside of the car then I won't be able to auto sync or really even manually sync the audio since the audio inside the car (with the mics) and the audio outside the car (camera audio) won't match for syncing. The car was super sound proof so I'm not sure if you can even hear the slate clapping when the windows were rolled up. My only idea at the moment is to crank up the audio all the way so I can just barely make out the slate clapping, then visually sync it.

This should only be a problem when the windows are rolled up and no exterior sound can be heard. Hopefully it's just a few clips here and there, but I won't be sure until I really get into it. Can anyone think of a better way to go about syncing for the times where that happened? I'm sure it's a bit confusing when typed out.

thanks,
GP


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Joe Marler
Re: Syncing Audio
on Jan 24, 2018 at 12:46:11 pm

[Glenn Payne] "The footage is prores 4444 so under the rendering option I'll select the 4444 setting and cut the footage as is, with no proxy or created optimized files. Does this sound workable to you guys??

I'm not sure you need 4444 as the project render format. The default is 422LT, which would be considerably faster since the render files are smaller. If needed you can change the render format to 4444 before final export. Maybe others could comment on this.

[Glenn Payne] "...My team was running the mixer's scratch track into the camera but occasionally they'd lose the feed. The film takes place in a car so the various mics were inside the vehicle with the actors. The camera was outside the car at times...So if we lost audio to the camera or were recording basically no sound on the outside of the car then I won't be able to auto sync or really even manually sync the audio since the audio inside the car (with the mics) and the audio outside the car (camera audio) won't match for syncing. The car was super sound proof so I'm not sure if you can even hear the slate clapping when the windows were rolled up. My only idea at the moment is to crank up the audio all the way so I can just barely make out the slate clapping, then visually sync it...."

When you slate, all cameras should be framing the slate. In fact some smart slates have a flashing light to notify distracted camera operators to pay attention. If your cameras all visually captured the slate it's just a straightforward manual sync.

If they did not, then it's harder. If your outside cameras had only a single audio source from the recorder, then you may have no camera audio at all. Higher-end cameras often have split audio inputs, so one channel of stereo audio can record wired input, and the other channel nat sound from an on-board mic. In that case there's a chance it might have weakly recorded the slate. Or maybe pre-roll or post-roll footage captured a car door slamming or other sound/visual to support a sync.

If the clocks of all cameras and recorders were accurately set before shooting, the clip date/time should be accurate within a few seconds. This should at least allow matching clip to clip, which is better than not knowing what clip goes with what take. If the clocks were not set right AND if the cameras did not frame the slate, AND if the outside cameras have no audio whatsoever, then you're possibly facing a time-consuming situation.

If the shoot was recent and the camera and recorder settings have not been modified since, you can sometimes inspect them and derive the time offset to local time, then update that in FCPX. E.g, if cam 1 is set to 9:45AM but the actual time is 10AM, then in FCPX you just do Modify>"Update clip date and time", and update all those clips +15 min. Do that for each batch of clips from each device and they'll at least sort chronologically adjacent in the Event Browser.

Short of using wired or wireless SMPTE timecode, a "cheap" way to avoid such cases is if all cameras support free run timecode and allow manual reset to zero by either button or IR/wireless remote command. This way no matter how many times the cameras are stopped/started, the onboard timecode will stay fairly close since the drift rate is usually fairly slow. Then in post you sync by timecode and touch up any mis-sync by a few frames if needed.

This situation illustrates why all camera operators should ideally monitor audio. If you lose camera audio and nobody notices, and if the camera operators are not framing the slate, then it's a lot harder. You then have to inspect each angle while listening to the audio and try to match it by observation and listening. It can take a while.


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Glenn Payne
Re: Syncing Audio
on Jan 24, 2018 at 3:52:42 pm

There are some solid ideas in there, Joe. Thanks again for chiming in. The pre-roll random noises is a good point. Maybe that will help out. And hopefully the number of takes this happens on will be minimal. The vehicle element just made some of the situations more different than the usual.

If leaving the render at 422LT works then that's great for me. I just didn't know if I'd be losing any quality. I have two drives with footage from the shoot. One has tons of free space and runs smoothly and the other drive is packed and is running very sluggish. I'm assuming that's due to the lack of free space on the drive so I'm sending a few reels from the packed one to the spacious one in hopes that'll help things operate better.

Thanks again for all the info!

Glenn


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Jeremy Garchow
Re: Syncing Audio
on Jan 24, 2018 at 4:33:15 pm

[Glenn Payne] "If leaving the render at 422LT works then that's great for me. I just didn't know if I'd be losing any quality. "

If you do have renders, and then you export, FCPX will use the LT renders on export and transcode to the export codec chosen.

If you want a true 444 export, you'lll just have to remember to delete the render files before you export.

Jeremy


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