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Audio NEVER sync's right

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Brandon Lanski
Audio NEVER sync's right
on Nov 2, 2018 at 2:06:52 am

Hey all! New to fcpx and have been experiencing constant problems with getting my audio to sync.

PAST PROBLEMS:

My first fcpx project I recorded a long interview using 4 channels on an external recorder and a boom straight into my GH5, my other GH5 was recording normal, nothing plugged into it. Did my audio sync in Plural Eyes. Everything checked out but when I brought my XML to fcpx everything was slightly out of sync, same with Davinci. Premiere oddly enough opened it fine.

I was able to manually get everything into place since it was all close enough but I found that one camera was drifting. I used retime to fix and that was that

I figured "fine, must have been some kind of glitch or mistake on my part. The frame rates were slightly different 23.98/24

Then we shot a concert and found that once we brought the footage in from PE everything was great in the beginning but then the audio started to slip. Only one camera was slipping though. So I again, used retime to solve

My third project I was sent a segment for a TV show to make a rough cut of. Usually my projects are sent to me already in sync but due a few issues I ended up having to do it. Same problem. How is it that back at the studio they seem to sync it just fine but it screws up over here?

CURRENT PROBLEM:

I told my friend about it and he said that frame rate differences have never stopped him from getting a solid audio sync. So when he sent me 3tb of footage that he and his guy shot for a party I crossed my fingers-

Well I've got a 5 hour multicam clip that 3 hours into, camera A at that point is showing something totally different than Camera B. I have a ton of audio tracks which are all very solid in sync. And everything stays in sync here longer than my other projects (Almost as if the length of my project has been dictating how off everything gets)

I gotta cut together a 45 minute video which wouldn't be so bad if it weren't for the fact this dude has a ton of live performances that he probably wants in his video.

Can somebody please give me ideas? Why does fcpx keep screwing up my audio?


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Jeremy Garchow
Re: Audio NEVER sync's right
on Nov 3, 2018 at 5:21:15 pm

What steps are you using to sync everything?


If the cameras and audio recorders aren’t jammed sync’d sometimes they will drift, especially over 5 hours.

You either have to sync manually, or use Plural Eyes which has a drift compensation feature, but even so, it’s not magic.

You say that all the audio is in sync, but the video is not.

If you isolate and play that clip where the video is not in sync with the audio, is it out of sync with itself? Meaning is the file not right?

Some cameras simply can’t handle that amount of sync, or use a variable frame rate which is very hard to track and keep sync in a time locked NLE.


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Brandon Lanski
Re: Audio NEVER sync's right
on Nov 5, 2018 at 6:38:56 pm

I think you're right. It was probably silly for me to think that multiple GH5's could maintain sync for hours at a time


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Tangier Clarke
Re: Audio NEVER sync's right
on Nov 4, 2018 at 3:39:10 pm

Brandon, consider WaveAgent to address the sampling header to the audio file. To be honest, I have had the best result with syncing using FCP X more than any other NLE. With third party apps, PluralEyes I only use if I have to and usually only for one feature - the sync drift. It's not a product I am fond of for various reasons which I've gone into in detail on other threads/forums.

I wrote this (https://forums.creativecow.net/thread/344/49664) some time ago. There may be some nuggets in there that are helpful.


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Brandon Lanski
Re: Audio NEVER sync's right
on Nov 5, 2018 at 6:25:24 pm

Tangier, your article was a great read. I'm certainly starting to have negative feelings towards Plural Eyes as FCPX seems like it would be doing a great job if I wasn't messing stuff up.

I reached out to my friend who gave me the project and he is much more knowledgable about Final Cut than I am. He told me that part of the reasons tings aren't syncing (even short, individual B-roll clips) is because the event was so long, it really opened lots of opportunities for "false positive" matches. While I'm glad my project isn't pregnant, It makes me wonder if all my footage that should have been able to sync, was given a place on the multicam. Not quite sure how I can check to see of Final Cut decided to stop trying with something.

I'm going to give wave agent a try. Would love to find that it's just camera audio that needs to be resampled.

Also, the last line in your piece confused me. "FCPX doesn't care about frame rate metadata on audio clips and try to adjust audio files based on FPS information."

Does this mean the frame rate is assumed using a method other than metadata? Not entirely sure how to take advantage of this fact.


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Tangier Clarke
Re: Audio NEVER sync's right
on Nov 6, 2018 at 6:34:07 pm

What I meant by that was that to my understanding FCP X is not syncing by metadata. It uses header information in the audio file as well as timecode, waveforms, sampling rate analysis perhaps.

When I used WaveAgent I don't think sampling rate of the file actually changed. What I believed happened is that the header information in the file itself (something we typically don't bother with) was changed and that is what gave FCP X what it needed to interpret the file differently. This is how a sound engineer explained it to me.

The FPS comment I believe was a matter of the timeline settings I believe in terms of how FCP X conforms picture with audio, but audio has no FPS. Lol, I knew what I was saying when I wrote it lol, but now I am scratching my head over that last bit.


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Tangier Clarke
Re: Audio NEVER sync's right
on Nov 6, 2018 at 7:00:25 pm

Brandon here's a post I wrote a few years ago on PluralEyes which elaborates more fully about it.

http://www.fcp.co/forum/4-final-cut-pro-x-fcpx/24392-to-fcp-x-or-to-plurale...


...and some additional notes I kept from testing PE 3.5. Not much has changed with PE 4.

PluralEyes (PE) 3.5 
One video clip/ one audio multichannel audio for each video clip.
Multichannel (interleaved) audio files

PE to FCP X XML no options checked
Synced clips exist only as project , no browser clips in sync.
Audio clips in synced project dead - not audible.
Audio clips in synced project missing channels from original audio.
Audio does point back to original audio in browser - defeats the point.
Useless without synced browser (bin) clips synced
FAIL

PE to FCP XML Event option checked
This replaces camera audio with 2nd system audio
Clips show in browser
No audio configuration available in FCP X inspector
No audio from synced clip can be heard
Audio shows synced audio inside clip (reveal clip in timeline), but is missing channels, no waveform, can’t hear
Audio is not trimmed to match video according to PE manual
FAIL

FCP X XML to PE then Back
This seems to work (sort of)
Synced clips are compound clips in FCP X*
Camera Audio was replaced (not sure I like that)
Audio in synced clips have two mono channels, original had three
Audio in synced clips points back to compound clip, not original audio (problem)
* Primary editing objects in FCP X are clips, synchronized clips and multicam clips, not compound clips as regular editing clips.  I wish third party apps would create an object the way FCP X would instead of a compound clip.  Compound clips create an extra layer of obstruction of the source media with regard to start/ end time, duration/ creation date/ and revealing in Finder.

Clips created in FCP X when all PluralEyes options are enabled before exporting, does in fact refer back to the original clips in the finder as originally shot rather than generating new Quicktime movies.  Though in FCP X, start, end, and durations have changed than if it had been done in FCP X only, simply because PluralEyes has trimmed the audio to match the video.

*There are times when the camera original audio is still useful, better, or absolutely necessary.  In this regard I still prefer the way FCP X syncs where it maintains camera original with the 2nd system sound at all times.  This way I don’t have to go hunting for the original clip at the precise sync point if and/or when I need it.  I am amazed that third party apps don’t accommodate this method.  In this regard I think FCP Xs only shortcoming for syncing is that it does not do batch processing and cannot quickly identify associated clips the way Dreamsync can.  I have worked on many shows where it is imperative that I have the camera original audio available.  I seldom ever want an application to replace the audio of my video clip.

In FCP XP, you still have to manually manage camera associations in order to build a proper multicam storyline to export as an XML for PluralEyes to handle and attempt to sync and bring back into FCP X.

Some pertinent questions using 3rd party apps for batch syncing.
How much do you value that your camera original audio is connected to the second system audio at all times? I like this feature about FCP X’s built in syncing capabilities.

-------------------------------------------------------------------------------------------------------------------------------------
My current workflow (using Tentacle Sync devices and sound created with Sound Devices units) is:
Offload cards with EditReady - rewrapped and for custom file naming.
Run video clips through LTC Convert (to reset timecode from the cameras to the TC from the Tentacles)
Import video and audio clips into FCP X
Export event XML for Sync-N-Link
Sync-N-Link does the syncing in a snap and sends that back to FCP X

This works great and it's fast. I can sync days of content in a matter of minutes. Literally.


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Joe Marler
Re: Audio NEVER sync's right
on Nov 5, 2018 at 1:55:42 pm

[Brandon Lanski] "Did my audio sync in Plural Eyes. Everything checked out but when I brought my XML to fcpx everything was slightly out of sync, same with Davinci. Premiere oddly enough opened it fine. "

If possible, I'd suggest not using PE but just FCPX. From a workflow standpoint there are several advantages to this. See procedure I outlined in this post:

https://forums.creativecow.net/thread/344/52517#52614

PE can correct sync drift but this is designed for "natural" sync drift from a poor crystal timebase on one recorder. It's not designed to fix a metadata problem, which you may have. The fact that Premiere doesn't show the problem yet both Resolve and FCPX do indicates it's probably not hardware-based drift. Each NLE is interpreting some metadata differently. This doesn't necessarily mean Premiere is doing it "right" and the other NLEs "wrong", it could be a grey area in how metadata is interpreted in certain edge cases.

Tangier's linked post is a good example of this -- I suggest reading that closely. You could download the free Wave Agent app and examine your problem files. You said only one camera was drifting. What does Wave Agent show for that file vs your other A/V and audio files?

I suggest making a backup copy of your files, make a test library in FCPX, then import the simplest test case which reproduces the problem if synced in FCPX -- say one camera and the polyphonic .wav file. Then examine those in Wave Agent.

If all audio sources are at 48Khz or 96Khz sample rates, there's usually no problem. If one is at 44.1Khz, that might cause sync drift. I think in that case the 44.1Khz source must be re-sampled, not just change the metadata.

However in Tangier's case he just changed the metadata sample rate to 48.048Khz and that fixed it.

Doing these tests will involve trial and error, but you really need to figure out the ultimate cause, not just try and work around it by stretching timelines.

Note: On High Sierra, the Wave Agent .dmg may not install, so you might need to locate the resultant .mpkg file, then right click, select "Open", and answer the security prompt.


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Brandon Lanski
Re: Audio NEVER sync's right
on Nov 5, 2018 at 6:37:24 pm

What you wrote in that post is actually what got me this far! I was having a terrible time with the angles but once I read what you said it became easy.

I set up the angles by doing a search in the event browser which would only show one camera at a time (I was lucky that all of my footage is VERY well named)

-- Set Camera A

-- Set Camera B

--Select everything that was sync-able (Individual tracks from multiple recorders)

Make a multicam clip.

Everything is perfectly solid for about the first hour. After a while, It's net even close. It's weird because these cameras weren't recording nonstop the whole night.


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Jeremy Garchow
Re: Audio NEVER sync's right
on Nov 5, 2018 at 8:01:12 pm

[Brandon Lanski] "Everything is perfectly solid for about the first hour. After a while, It's net even close. It's weird because these cameras weren't recording nonstop the whole night."

So make multiple multiclips and see if it keeps sync?

Just to reiterate, all video clips are in sync with themselves right?

Meaning you can watch any single clip and the audio is in sync with the video?


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Brandon Lanski
Re: Audio NEVER sync's right
on Nov 8, 2018 at 6:55:56 pm

No, the only thing which stays in sync are the audio tracks (Console recording from the mixer, external h5's etc) Camera-A and Camera-B fall out of sync with these audio tracks differently.

I was able to find a work around. I went into my multicam clip where things eventually fell out of sync and looked for parts of the event I needed in sync. Even if there was a ton of drift, this still helped. I then found a clip, and searched for 2-4 clips from another camera angle which would likely sync up and then I found them in the event browser.

To put it another way, I used my multicam to help me look for the video clips I wanted in sync and then I selected them in the event viewer. I then would sync it to my main console audio. Now I have a bunch of multicam clips where about 15-30 minute parts of the party are in sync with B-roll.

In order to integrate my other sound sources so I can have room echo and crowd noises, I'm going to see what happens when I try to sync after I turn my finished project into a compound clip.


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Jeremy Garchow
Re: Audio NEVER sync's right
on Nov 8, 2018 at 7:46:59 pm

The

[Brandon Lanski] "Camera-A and Camera-B fall out of sync with these audio tracks differently. "

But at that point in time, if you listen to camera A and camera A's audio, is the audio in sync with the video? Or is the audio out of sync on the camera recording (not the console recording).


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Joe Marler
Re: Audio NEVER sync's right
on Nov 8, 2018 at 9:17:06 pm

[Jeremy Garchow] "But at that point in time, if you listen to camera A and camera A's audio, is the audio in sync with the video? Or is the audio out of sync on the camera recording (not the console recording)."

This is a good question. If (by chance) Cam A video and Cam A audio are ever out of sync, this implies something unusual.

However I think his problem is the one discussed in this frame.io article. Note Brandon is trying to sync 24 fps and 23.98 fps material with external sound recorded at an unknown frame rate.

"When using an external sound recorder, it too must have 23.98fps as an available choice, or there will be drift between the sound and picture...Whatever you do, be consistent. Don’t mix footage with different frame rates.."

https://blog.frame.io/2017/07/17/timecode-and-frame-rates/

Of course audio doesn't have a real frame rate -- it's recorded in samples. But it does have metadata which may contain a frame rate, and which various software can interpret differently, especially when conforming differing frame rates. This is the point Tangier was making in his earlier post.

Brandon might be able to laboriously work around the problem, but the underlying issue should ideally be investigated and resolved. A better workaround might be to use WaveAgent to modify the file metadata then re-import. To know what file to change, first use WaveAgent to examine all the files and write down which is the oddball group. If they are all 24 fps except for the one 23.98 fps camera, maybe try to change that one's metadata to 24 fps. But I really don't know -- this could require trial and error. If that doesn't work, some files might require resampling or even re-encoding.

Besides this issue, Jeremy's statement is correct that long term sync (over hours) is not assured unless you have common timecode. The quartz oscillators in regular cameras are like a cheap wristwatch. They are pretty good but can drift over several hours. So Brandon may have two different issues -- a more rapid drift problem caused by the 23.98/24 conform, and a slower drift problem caused by a camera timebase.


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Brandon Lanski
Re: Audio NEVER sync's right
on Nov 12, 2018 at 3:43:37 pm

The camera's always seem to have their audio in sync. (A with A B with B but A not always syncing up with B)

After trying to sync smaller chunks at a time, I've realized that maybe fcpx gets confused and has a tendency to place things in the wrong places. I don't know how the algorithm works but I guess if two songs have transients which look similar, a clip could be placed at the wrong place.

Still waiting to get wave agent on my system. But I will report back with what it tells me


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