DVD Titles Defaulting to 30fps instead of 24fps?

[paulmovies33b]

Just getting started with backing up my disc collection, first time using makemkv and noticed something unexpected.

If I backup up a DVD as an ISO it will playback in 24fps as it should (verified by looking at signal information at the display). Ripping the main title to an mkv will only play in 30fps. Tried Kodi, Potplayer, VLC, all the same.

Looking at the video track header in MKVToolNix the "Default duration" element is set to 33366666 (29.97 fps), but If I look at the mkv file in MediaInfo it shows the following for the video track:

Frame rate mode: Variable
Frame rate: 23.976
Original frame rate: 23.976
Scan type: progressive
Scan order: 2:3 pulldown

So it appears that when makemkv is ripping titles it is not recognizing them as 24fps even though it seems like it should?

I used MKVToolNix to change "Default duration" to 41708000, players recognize the file as 24fps and everything seems to work, no audio sync issues.

Questions:

1) Is there some setting I am doing wrong when ripping the titles or is this a bug in makemkv and I will need to edit the files after creation?

2) Any downsides to changing the "Default duration" element if I am consistent with changing it to the frame rate reported by Mediainfo?

Thanks in advance for any help.

[Woodstock]

DVDs are typically 25 or 30 full frames per second, depending on whether they're intended for European or US markets. Typically, they're also interlaced, so the effective frame rate is 50 or 60 half frames per second.

What are you playing it back with that says 24fps for the data itself? A number of players "fudge" the information to match the display.

[paulmovies33b]

Using Kodi on a PC as the player and have it set to adjust the display refresh rate on start/stop. When the movie starts I see the resolution switch and then verify the signal format on my projector.

My (limited) understanding was that some DVDs have 24fps data on them but include information on the DVD to help the player convert to 30fps if necessary (soft telecine?).

In any case, I have three scenarios:

1) I play the actual DVD in my Sony UHD player and it outputs a 24fps signal to my projector.
2) I play the iso I backed up with makemkv through Kodi and it outputs a 24fps signal to my projector.
3) I play the main title ripped to a MKV file through Kodi and it outputs 30fps to my projector, unless I adjust the header info as mentioned.

There is something different between the iso and the mkv when I though that they would behave the same.

[Woodstock]

At a guess, I'd say the Sony is adjusting the display rate to match what BD/UHD expects (24fps). A straight DVD player would output either 25/50 or 30/60 fps (full vs half frames), but if the player is a BD-capable unit, it may convert to what the TV/monitor expects.

Where you will see it is in high-action scenes, where the half frames will be wildly different from the full frame you'd see on a BD. Often, you'll see the frames overlap, which is REALLY bad in some scenes where there is a background of horizontal lines (think window blinds) at a slight angle from horizontal.

But this is going to be an issue with any DVD source video, whether it's shown at 24, 25, or 30 fps. It is inherent in the way the video is stored as interlaced half frames.

[paulmovies33b]

Interesting, thanks for the info. Couple more questions:

Why would MediaInfo say that the video track in the mkv file is progressive and 24 fps if it was really interlaced at 30fps?

Why would the iso and mkv from the exact same disc, through the same player, to the same display, play at two completely different frame rates (24 fps vs 30fps) if the underlying video data is exactly the same? No remuxing, just straight defaults with makemkv.

Just trying to wrap my head around everything, I have several hundred DVDs to backup and want to make sure I do it right

[tomty89]

Using Kodi on a PC as the player and have it set to adjust the display refresh rate on start/stop. When the movie starts I see the resolution switch and then verify the signal format on my projector.

My (limited) understanding was that some DVDs have 24fps data on them but include information on the DVD to help the player convert to 30fps if necessary (soft telecine?).

In any case, I have three scenarios:

1) I play the actual DVD in my Sony UHD player and it outputs a 24fps signal to my projector.
2) I play the iso I backed up with makemkv through Kodi and it outputs a 24fps signal to my projector.
3) I play the main title ripped to a MKV file through Kodi and it outputs 30fps to my projector, unless I adjust the header info as mentioned.

There is something different between the iso and the mkv when I though that they would behave the same.

It's totally normal and this is really just about whether / how the player decide to ignore the soft pulldown. I suppose the reason that they do not do so with MKV is because essentially the muxing would keep a "copy" of the pulldown as frame durations.

Probably a MKV demuxer could be made to assume certain durations pattern to be pulldown and decide to ignore them and fix to the shoter among the two, effectively disabling the pulldown, but I'd say technically it's not exactly safe to make such assumption.

I don't know much about VOB / MPEG-PS muxing, but AFAIK in case of such container, players would just check a combination of corresponding flags in the MPEG-2 video stream and decide whether there is pulldown and can potentially be disabled, but usually even for that you'd need to enable "24p output" / "cinema mode" in the settings (for cosumer players like your Sony; no idea about Kodi). (It's not always safe to disable the pulldown and/or enable 24p output as many DVDs have pulldown materials mixed with interlaced materials; but perhaps some player implement mechanism to drop frames for the latter)

Also I don't think there's a way to signify in the MKV muxing that the video stream is "purely" (soft) pulldown materials. (Maybe there is with DVD / VOB.)

P.S. If you want 24p (more precisly 23.976p) playback for MKV made from DVD, IMO what you should do is find a tool that allows you to remove the soft pulldown in the video stream (and have that remuxed). (But again whether it is a good idea entirely depends on whether source is "pure".)

[paulmovies33b]

Thanks for the replies.

I'll leave things as defaults and not try to force 24fps, sounds like it could cause more problems than it is worth, especially as I wouldn't visually notice the difference anyway.