Wait.
You have to “calibrate” your system and find out where the problem is.
It probably isn’t your system.
Because if the audio & video were exported incorrectly, or with a crappy codec/on a crappy machine / by a crappy operator (pick one or multiple) and you don’t have a White Frame + 2pop, then you can’t possibly know what the correct sync is.
In normal conditions, the onboard video player should be correct.
When using a Blackmagic card of the likes, you need to compensate for that card + the TV-screen.
To test your system you need two things.
- A leader tape of some kind where you have a clear 1 frame white flash.
(Import the video in Nuendo and place a 1 frame 1kHz precisely where the White frame in the video is.
2, A device that can measure the the offset (in playback) between the video White Frame Flash and the audio 2pop.
Catcin’ Sync might not be the most accurate device in the world, it is the cheapest and best solution, and it will you a perfect result.
https://quietart.co.nz/catchinsync/
On the site, you can download test files and a tutorial.
Once you have done that, and calibrated your system, you will be 100% sure that any problems you bump into have occurred during creation of the video.
HTH
Fredo