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.

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yassera-s wrote on 11/16/2020, 5:04 PM

Did he use the same audio source you are using?

Yes he used exactly the same audio file I am using. I gave him all raw footages along with the song track in MP3 format.

He converted the raw footages to proxy files for easy editing in Premiere Pro. He rendered it to MP4 file for me to check his editing, but I did not like it and rejected his editing and I decided to edit it my self in Vegas Pro 17. But I am now facing big problem with syncing a shot that I liked from his editing!

yassera-s wrote on 11/16/2020, 5:09 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.

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

Not related to NTSC PAL issue. We filmed the music video with Alexa LF in 2K at 50fps (PAL). When filming, the singer was signing with the sound coming from the playback device, but unfortunately we did not record any audio into the camera.

eikira wrote on 11/16/2020, 5:12 PM

Not related to NTSC PAL issue. We filmed the music video with Alexa LF in 2K at 50fps (PAL). When filming, the singer was signing with the sound coming from the playback device, but unfortunately we did not record any audio into the camera.

yes i understand that, but what audio device was that recorded it you recorded offcamera? for example i have a zoom f6 and can set FPS for sync on it independenty from camera. if you know what i mean.

what video file is it exactly? maybe just rewrap it into a diffrent container would help? with ffmpeg.

lenard wrote on 11/16/2020, 5:16 PM

You could post your full mediainfo for the file. Maybe it would show something interesting

yassera-s wrote on 11/16/2020, 6:32 PM

Not related to NTSC PAL issue. We filmed the music video with Alexa LF in 2K at 50fps (PAL). When filming, the singer was signing with the sound coming from the playback device, but unfortunately we did not record any audio into the camera.

yes i understand that, but what audio device was that recorded it you recorded offcamera? for example i have a zoom f6 and can set FPS for sync on it independenty from camera. if you know what i mean.

what video file is it exactly? maybe just rewrap it into a diffrent container would help? with ffmpeg.

I know what you mean, but we did not record any audio during the filming. We did playback the song on loudspeaker so the singer can sing along with it. Here is MediaInfo of the file:

yassera-s wrote on 11/16/2020, 6:36 PM

I recorded the screen for you to see what is going on. I am trying to sync the raw footage to the MP4 exported from Adobe Premiere Pro. I put the raw footage above the MP4 and used the transparency to check the sync.

Please watch the video from this link:

eikira wrote on 11/16/2020, 6:42 PM

I know what you mean, but we did not record any audio during the filming. We did playback the song on loudspeaker so the singer can sing along with it. Here is MediaInfo of the file:

it would be easier next time to just save the txt file and upload it :-p

so what about with a rewrap? or a recode in lossless h264 (h264 is also able to maintain 4:4:4 and 10 bit) ? just to see if maybe the problem lies in prores for your computer? did you tried that and did you took a look into vegas pro project settings?

ah yes, its with your video very clear what the problem is. i think for some reason your vegas does not handle the prores original correctly. try to enable the old quicktime plugin (or disable it) under options->preferences->outdated functions->quicktime-plug-in activating

lenard wrote on 11/16/2020, 6:47 PM

It looks like you're moving the clip instead of stretching it, the first and last frame will be in sync if you stretch, but depending on what's wrong, it may still drift in the centre

yassera-s wrote on 11/16/2020, 6:54 PM

@eikira Sorry I tried uploading the text file and did not work, so I had to make screenshot 😅

I do no think the problem is related to ProRes because we filmed everything in ProRes and it is synced correctly to the audio in Vegas Pro. We shot some shots in normal speed and others in slo mo, and the syncing problem only with slo mo footages. However, I open to suggestion and will use Catalyst to Prepare to transcod the file to another format.

yassera-s wrote on 11/16/2020, 7:07 PM

It looks like you're moving the clip instead of stretching it, the first and last frame will be in sync if you stretch, but depending on what's wrong, it may still drift in the centre

@lenard Oh man! You saved my life thank you very much. 👍👍👍

Stretching solved the problem and I don't know why I did not try it!

Stretching did not work before when I was trying to sync the footage to the audio track and I assumed it will not work when syncing video to video duh me 😅 THanks again man.