Server Version#:4.22.3
Player Version#: Various
I ripped the new Monty Python set to mkv files. All the programs have the BBC slate, countdown clock and announcer with variations on announcing and counting down from 30 seconds or so.
I used MOVAVI for Mac to trim the first 30 seconds or so, to the blackout after the countdown ends, and now each file’s audio and visuals are out of sync. This is true in the file itself, even when not played within plex.
Is anyone familiar with how to fix this?
Get MKVtoolnixGUI
and use the ‘delay’ to correct the audio track.
You can use e.g. MPC-HC to determine the right number relatively quickly. It supports changing the audio delay by using the +/- keys and shows the current number on screen.
You might want to use MKVtoolnix for cropping in the first place as well. 
Not easily.
I gave up early and I have all the tools (PC) to do it with.
VideoReDo to trim the offending ‘slate’ - Frame Accurate - in a Remux ‘Smart Edit’ - but that does strange things to the video/audio. <—VRD is excellent at editing MPEG-2 - not so much for 264.
What did I do for THE BEST MONTY PYTHONS WE’LL EVER SEE?
Nothing.
I use VPTs on my Roku to FF the 30 seconds.
I’ve been chasing good Monty’s for decades (every decade since the one they aired in - literally) - now that I have 'em - I’ll keep 'em intact, thank you very much.
I couldn’t have thought of a worse way to ‘set these apart’ from all others - and the person(s) responsible for what they consider ‘cool’ should suffer Cleese’s Angry Fist Shake - unless it was Cleese who thought up such nonsense, but it is, what it is… unfortunately.
I’ll bet we get another version, sans intro one day, but for now - these remain un-fiddled.
Take That, you scoundrels!


PS:
Otto’s method will get you very close - keep your originals intact - you’ll be glad you did.
Fix… As stated, OttoKerner is a good close…
I’m not familiar with Mac or the program you use but am familiar with trimming video files. I have used many for Windows. My favorite is by far, SolveigMM Video Splitter. It take a whole minute to understand the interface but well worth it! And what do you know… There’s a Mac version.
On another note… If you do not want to be splicing your files then you can add a chapter at the 30 or so seconds.
All this also assumes you won’t be needing those subtitles.
If you do best try first - while they’re still embedded - and with 'em out - 'cause I think right in here somewhere is a show stopper.
No, none of the existing subs work - that pesky 30 second intro - and the ones that do work are VOB/PGS (pick one - can’t recall). Oh how I loathe an OCR session, but sat through each and every one for this once in a lifetime media grab.
It was painful, but worth it.
… and no - I didn’t spell check this one…:

SolveigMM Video Splitter actually supports all kinds of subtitles including embedded idx/sub.
Before split
After split - part 1
After split - part 2
What happens when you cut a big hunk off one end?
That’s where VRD fails miserably - so maybe something else will do better.
Define big hunk? I mean, I split the episode almost in halve. That’s about 50% loss from either end. But, to your point.
Nothing as these pictures will show. The program will adjust the subtitle offsets accordingly.
Instead of halving the episode I cut all but 3 minutes.
Part 1 (46m03s) 831 subs to display

Part 2 (03m21s) 30 subs to display

Thanks. I’ve installed a vmware vm running windows so i can use windows video editors Going to give that a try