Audio rips from video files

I’ve just seen a thing where the audio ripped by Nuendo is out of sync - i.e. when the audio file produced by the rip is positioned at the start of the video file, sync is off. I thought it odd, so I played the H264 in a standalone player and all was good. So I ripped the audio from the same file using pro tools. This was in sync. There are 13 extra frames of silence at the head of the audio files made by Nuendo (in this case 7 but I have seen this in 8). Seems to be a problem with some video files. Anyone?
See pic.

I’ve seen this too with certain videos where the audio and video streams are of different durations.