DVD - 29.97 or 23.976 fps?

[geohei]

Hi.

I used DVD Decrypter to rip a DVD. I use VirtualDub-MPEG2-AC3 (VD) load the resulting VOB and to cut parts of it.

VD Fileinformation says that the stream is 29.97 fps (with 167502 frames, 1:33 hours). The DVD player says it's 1:56 hours long.

1:33 corresponds to 29.97 fps.
1:56 corresponds to 23.976 fps.

Also, when playing the stream using VD, I have to adjust the framerate to 23.976, otherwise a/v is out of sync.

I was told in the german doom9.de forum, that 23.976 DVDs don't exist. How is it otherwise possible that I have to adjust the framerate of VD to 23.976 and that the standalone DVD player confirms this by showing 1:56 as play time?

TIA

[Kika]

Like i wrote in the german Doom9: 23.976 FpS is a correct setting for NTSC-DVDs. The Video has to be encodet with 3:2-Pulldown on Playback. This instructs the Player to convert the Video to 29.97 FpS while Playback.

[mpucoder]

Jeez, I hope you didn't imply 23.976 was the only frame rate for NTSC. It can be either 23.976 or 29.97, and even mixed within the same cell. In fact, to paraphrase Jim Taylor (author of DVD Demystified) the source framerate can be anything that when combined with the proper pulldown flags (2:3 is not the only sequence) yields 29.97fps

The real answer is to keep it the same as the original, and this can get tricky on hybrid (mixed film and camera) video, and to use 2:3 pulldown on 23.976 material..

[geohei]

What I did now is frameserving the VOB from VirtualDub (using the frame rate adjust option to 23.976), and reencoding it with TMPGEnc, setting the "3:2 pullown" flag. This maintains the number of frames and keeps a/v in sync.

Thanks for the help.

[Kika]

But watchout for possible interlaced effects, like mpucoder wrote, sometimes you will find DVDs with mixed material.

[geohei]

Good to know. Thanks a lot!