Weird MPEG-2 video files

[MaximRecoil]

I don't know which subforum would be best to post this in. I'm not trying to encode anything, but I've encountered some weird MPEG-2 files that were encoded by someone.

I'm using MakeMKV to copy a TV series DVD set to my computer so that I can watch them without having to swap discs after every 4 episodes and sit through the annoying unskippable stuff at the beginning of each disc. I'm leaving them in their original MPEG-2 form (no plans to re-encode them).

The video files from seasons 1 through 4 were all normal, but starting with season 5 they got weird. All of them show at least 2 different frame rates, and some of them show 3, when you look at the properties in MPC-HC. Here's one example:

Frame rate: 24.464 FPS

Original frame rate: 23.976 (24000/1001) FPS

Video: MPEG2 Video 720x480 (4:3) 29.97fps [V: English [eng] (mpeg2 main, yuv420p, 720x480)]

The oddball 24.464, the film 23.976 (even though these DVDs had Betacam masters), and the correct 29.97 are all for same video file.

The oddball frame rate varies randomly from file to file, and sometimes the 23.976 one isn't there, leaving only 2 contradictory frame rates: the oddball one and the correct 29.97 one.

Two of the episodes so far were even weirder, because they had contradictory display aspect ratios in addition to contradictory frame rates: 16:9 and 4:3 (the correct DAR for all episodes is 4:3, as this TV show ran from the late 1980s to the mid 1990s). With those two episodes, if I played them in MPC-HC directly from the DVD, selecting them from the DVD's menu, they displayed in the correct 4:3 AR, but if I played the MKVs from MakeMKV, they displayed in the wrong 16:9 AR.

I was able to fix the DAR on those two files by remuxing them in tsMuxerGUI and selecting 4:3.

Does anyone have an explanation? I didn't think that DVD video specifications even allowed oddball frame rates, let alone multiple ones, nor two different DARs, all for the same video stream. How was that even accomplished?