Can not sync video to audio!

yassera-s wrote on 11/14/2020, 7:18 PM

I have a video clip of a singer that was shot at 50fps. The duration of the clip is 5:37 minutes and I am trying to sync it to the same song we were using when filming the clip, but the sync does not hold all the way as it starts loosing the sync after around 15 seconds! What is going on?

 

For the record, the clip was filmed with Alexa LF at 50fps, but it seems the DIT converted the clip back to 25fps before giving me the files and the clip now runs in slow motion when I put in the timeline. So I had to change the playback speed of the clip to 50fps in order to play at normal speed.

Comments

Former user wrote on 11/14/2020, 8:47 PM

Yep. That can happen. Unless you were using some type of timecode generator or genlock system, you are the mercy of the quality of the playback of the audio and the camera recording. Your options are to edit in such a way to allow you to readjust the sync, or change the playback speed of the song, and you might have to adjust as you go along.

Former user wrote on 11/14/2020, 9:04 PM

One other thing to try is use the same device to play the audio back that you used when you shot the video and record it back into your computer. That might give you a better chance of syncing.

lenard wrote on 11/14/2020, 9:38 PM

After you sync the first frame of audio camera track to music audio track, go to the end and stretch or shrink your audio track so that the wave form at the end is sync, now check if sync remains or still drift?

yassera-s wrote on 11/15/2020, 9:44 AM

Yep. That can happen. Unless you were using some type of timecode generator or genlock system, you are the mercy of the quality of the playback of the audio and the camera recording. Your options are to edit in such a way to allow you to readjust the sync, or change the playback speed of the song, and you might have to adjust as you go along.

Yes it seems this is the only solution and I have to cut the video at every 15 seconds and adjust as I go! Thanks.

yassera-s wrote on 11/15/2020, 9:45 AM

One other thing to try is use the same device to play the audio back that you used when you shot the video and record it back into your computer. That might give you a better chance of syncing.

Unfortunately the playback device is not available!

yassera-s wrote on 11/15/2020, 9:58 AM

After you sync the first frame of audio camera track to music audio track, go to the end and stretch or shrink your audio track so that the wave form at the end is sync, now check if sync remains or still drift?

Unfortunately we did not record the audio into the camera when filming which is big mistake as it made the editing harder when syncing.

I tried your idea and it did not work! I synced the first frames and everything looks fine, but when I sync the last frems, the sync in the first frames is drifted again!

ccliffy wrote on 11/15/2020, 10:07 AM

what is fps of project. I was under impression it had to match footage or vice versa

yassera-s wrote on 11/15/2020, 10:23 AM

what is fps of project. I was under impression it had to match footage or vice versa

@ccliffy The frame rate of the project is 25fps matching the clip frame rate.

yassera-s wrote on 11/15/2020, 10:24 AM

Is there a 3rd party tool that can help to perfectly sync the video track to the audio track?

ccliffy wrote on 11/15/2020, 10:25 AM

Plural eyes works great

yassera-s wrote on 11/15/2020, 10:48 AM

Plural eyes works great

Thanks .. will give it a try.

Former user wrote on 11/15/2020, 11:12 AM

Plural eyes won't fix the sync. It will only allow you to sync duplicate audio sources.

wwaag wrote on 11/15/2020, 12:00 PM

"Plural eyes won't fix the sync. It will only allow you to sync duplicate audio sources."

Beginning with V4, that's no longer the case. Here's an excerpt from their website.

Automatic Drift Correction (NEW)

On long clips, sound and video can stop matching up perfectly. Unlike any other sync tool in the industry, PluralEyes can account for that and export a perfect sync. New in version 4, if drift is detected, PluralEyes automatically fixes it, and gives you the option to toggle between the drift corrected sync and the original audio without correction applied.

AKA the HappyOtter at https://tools4vegas.com/. System 1: Intel i7-8700k with HD 630 graphics plus an Nvidia RTX4070 graphics card. System 2: Intel i7-3770k with HD 4000 graphics plus an AMD RX550 graphics card. System 3: Laptop. Dell Inspiron Plus 16. Intel i7-11800H, Intel Graphics. Current cameras include Panasonic FZ2500, GoPro Hero11 and Hero8 Black plus a myriad of smartPhone, pocket cameras, video cameras and film cameras going back to the original Nikon S.

yassera-s wrote on 11/15/2020, 12:12 PM

Plural eyes won't fix the sync. It will only allow you to sync duplicate audio sources.

I think you are correct! I downloaded the trial version and can not find a way to fix my problem!

yassera-s wrote on 11/15/2020, 12:14 PM

"Plural eyes won't fix the sync. It will only allow you to sync duplicate audio sources."

Beginning with V4, that's no longer the case. Here's an excerpt from their website.

Automatic Drift Correction (NEW)

On long clips, sound and video can stop matching up perfectly. Unlike any other sync tool in the industry, PluralEyes can account for that and export a perfect sync. New in version 4, if drift is detected, PluralEyes automatically fixes it, and gives you the option to toggle between the drift corrected sync and the original audio without correction applied.


@wwaag  I dont think this will work in my case! The clip was filmed without audio! Please correct me if I am wrong!

wwaag wrote on 11/15/2020, 12:18 PM

@yassera-s

"I dont think this will work in my case! The clip was filmed without audio!"

Sorry, I didn't see that. You're absolutely right. Perhaps you need a "lip reader". LOL.

AKA the HappyOtter at https://tools4vegas.com/. System 1: Intel i7-8700k with HD 630 graphics plus an Nvidia RTX4070 graphics card. System 2: Intel i7-3770k with HD 4000 graphics plus an AMD RX550 graphics card. System 3: Laptop. Dell Inspiron Plus 16. Intel i7-11800H, Intel Graphics. Current cameras include Panasonic FZ2500, GoPro Hero11 and Hero8 Black plus a myriad of smartPhone, pocket cameras, video cameras and film cameras going back to the original Nikon S.

yassera-s wrote on 11/15/2020, 12:27 PM

@yassera-s

"I dont think this will work in my case! The clip was filmed without audio!"

Sorry, I didn't see that. You're absolutely right. Perhaps you need a "lip reader". LOL.


"lip reader" 😂

Former user wrote on 11/15/2020, 2:03 PM

@wwaag I did not know that, good to hear. But as yassera-s said, he has no reference audio.

wwaag wrote on 11/15/2020, 4:24 PM

@Former user

I've not tried V4 since I still use the original Singular version which supports audio subframe offsets whereas later versions (V3.5 at least) are only frame accurate.

AKA the HappyOtter at https://tools4vegas.com/. System 1: Intel i7-8700k with HD 630 graphics plus an Nvidia RTX4070 graphics card. System 2: Intel i7-3770k with HD 4000 graphics plus an AMD RX550 graphics card. System 3: Laptop. Dell Inspiron Plus 16. Intel i7-11800H, Intel Graphics. Current cameras include Panasonic FZ2500, GoPro Hero11 and Hero8 Black plus a myriad of smartPhone, pocket cameras, video cameras and film cameras going back to the original Nikon S.

lenard wrote on 11/15/2020, 5:07 PM

After you sync the first frame of audio camera track to music audio track, go to the end and stretch or shrink your audio track so that the wave form at the end is sync, now check if sync remains or still drift?

Unfortunately we did not record the audio into the camera when filming which is big mistake as it made the editing harder when syncing.

I tried your idea and it did not work! I synced the first frames and everything looks fine, but when I sync the last frems, the sync in the first frames is drifted again!

So it's not a constant drift. That can happen with Variable frame footage when moved into Vegas, but alexa wouldn't be using variable frame. I"m out of ideas

yassera-s wrote on 11/15/2020, 7:01 PM

@lenard  No it is not constant drift, and that is the problem!

It was shot with Alexa LF and I asked the DOP to shot it at 50fps (2K) assuming that it will be very easy to sync later on in post, but I was wrong! I should have insisted on using on-camera mic and that was another big mistake!

yassera-s wrote on 11/16/2020, 4:38 PM

Guys, I just discovered that my old editor did not face the same sync problem I am facing now! When he was editing my video, he perfectly synced the exact same clip I am trying to sync now! How is that possible? Can anyone help explain what is going on?

He used Premiere Pro for editing, is it possible that this sync problem is related to Vegas Pro?

Former user wrote on 11/16/2020, 4:49 PM

Did he use the same audio source you are using?

eikira wrote on 11/16/2020, 5:01 PM

Is there a 3rd party tool that can help to perfectly sync the video track to the audio track?

Plural eyes works great

i doubt that plural eyes is good for streching an audiofile.

 

so as far as i can tell it seems like a clear FPS audio issue. meaning for some reason you got audio from a device that is hard on deleting portions of audiofragments for frames. i mostly would say it sounds like an NTSC PAL issue or round NTSC to NTSC 23.976/24 etc.

if you can figure it out what the exact input was you could reencode the audio with EAC3to 50->25 60->59.94 29.97->25 and so on into wav or flac.
https://www.videohelp.com/software/eac3to

i have no clue if that helps you but maybe gives you an idea what could be done or to figure it out more.

also maybe you should take a look into vegas project settings in the audio and scaling tab. changing audio sampling and stretching quality to optimal and scaling maybe to frames and time etc. just check if for some odd reason it could have an effect.