Confused over frame rates being changed

[tomty89]

So then if I want to rip my DVDs to mkv, I guess the best answer is to trust Makemkv

Maybe. I wouldn't say that it must be doing everything correct, but it's probably good enough. I know too little about video codecs and Matroska itself to tell about certain stuff.

don't worry about what mediainfo reports about the frame rates (23.976. 24.000, or 29.970)?

Well the problem is, even if you should worry about it, what's next? Are you willing to analyze the video streams of the different shows or episodes and find out how they are really different? I mean something like literally looking into picture headers. (And before that, find out what tools you can use to do so -- assuming there's even a good enough one.)

It would be great if you can do that and then isolate what mkvtoolnix or makemkv might be doing wrong, but it's not exactly a trivial task.

[mattias83]

Yeah, that might be a bit beyond what I can do.

Just to be on the safe side I was dropping the files into mediainfo assuming if something was off, it would tell me. Unfortunately, it seems like DVD ripping can get messy due to a number of reasons, and without knowing why each file is being muxed the way it is, like you said, I guess there's not much else I can do anyways.

I thought mkvtoolnix was certainly something I could trust when it comes to the odd task now and then like ripping specific chapters or timestamps, but it seems even that appears to have issues.

If there's any other software that's more suitable for doing what I want - ripping DVD features and extras, easily with a GUI, I'd love to hear it. But it's looking like makemkv, for better or worse, and hoping the files it puts out are okay.

[tomty89]

For one AFAIK the maintainer of mkvtoolnix is a "one-man band". On and off it receive pull requests from other people but that was it. So you can't really expect / ask for much. It wasn't in "heavily maintained state" even back when I made my tiny contribution, especially not the MPEG-2 / DVD related code. The maintainer explicitly mentioned that he would rather / have to devote the time he has to maintain the code for modern format / codecs (but is open to PRs / fixes from others).

[mattias83]

So he closed the bug request and this was his comment:

"Not a bug. Matroska uses plain integers for both the default frame duration & the frame timestamps. Therefore they cannot express irrational numbers such as 30000/1001 precisely."

Does this make any sense to you? I don't understand this since we know mkvs from makemkv indeed play in VLC at the correct frame rates of 23.976024 and 29.970030. So this doesn't explain why mkvs from mkvtoolnix play in VLC at 23.976216 and 29.970628.

How can they both be correct? One has to be off, right?

[tomty89]

My guess is he didn't bother to read carefully. Maybe you can try reinstating you are aware of that and the problem is that "error" you saw is far more significant than it should be for just the integral conversion. (You may also suggest that he should pay attention to the millisecond part. I don't know if that would work out well though.)

P.S. You may also ask him to note that int() was applied in the formula where the correct / expected values was returned.