30fps to 29.97fps

[bobkart]

Say I've encoded to MPEG2 suitable for DVD but used 30fps instead of 29.97fps.

Is there a utility out there than will let me 'patch' the MPEG2 file to say it is 29.97fps, so authoring applications will accept it?

I have found that converting originally 30fps source material to 29.97fps MPEG2 does not do as good of a job at preserving the quality of the original material. Since in this case I don't mind the 0.1% time difference, and won't even be having any audio track so no audio/video synchronization to lose, I'd like to do the conversion to 30fps MPEG2 then patch it to 29.97fps.

In fact I believe this is what standalone DVD Recorders do, many User Manuals have a disclaimer about given-length recordings coming out a bit short when played back due to the incoming signal being at 30fps but being played back at 29.97fps (3.6 seconds short per hour).

I am using TMPGEnc both for MPEG2 encoding and DVD authoring by the way.

[manono]

Hi-

I have found that converting originally 30fps source material to 29.97fps MPEG2 does not do as good of a job at preserving the quality of the original material.

That doesn't make a helluva lot of sense. You haven't said exactly how you do the conversion, but a simple AviSynth command of AssumeFPS(29.97) will wind up giving you exactly the same quality. Maybe when you do it using other methods you wind up blending the frames. Anyway, ReStream can do the 30->29.97fps conversion by slowing playback. I suppose something like DVDPatcher can also, but I've never used it.

I see you've edited. I don't know your TMPGEnc settings, and can't advise anyway (except to suggest switching to frameserving via AviSynth), as I don't use it.

[bobkart]

Sounds like there are shortcomings to the toolset I am using.

I'd love to be able to tell TMPGEnc to assume the incoming material is already at 29.97fps, then it won't do the blending thing that I am trying to avoid. Or to be able to tell TDA to consider the incoming 30fps MPEG2 files as 29.97fps. So that's what I'm trying to find a way to do, without having to give up on using TMPGEnc as the MPEG2 encoder. Other authoring applications you say may support 30fps MPEG2 files? Any in particular?

Thanks for your help.

[manono]

Hehe, I edited as well. Not so sure about the authoring apps now, and decided to remove that comment. The drop_frame flag is set when applying pulldown.

[bobkart]

I don't want to mess with the video that am changing from 30fps to 29.97fps. Just keep all the frames the same, but declare them to be played at 29.97fps instead of 30fps so TDA will accept it for authoring.

Just checked out DVDPatcher and it looks like it will let me set the fps to 29.97. I'll give this a shot.

EDIT: Looks like that works, thanks manono!

[manono]

I don't want to mess with the video that am changing from 30fps to 29.97fps.

Neither ReStream nor DVDPatcher messes with the video, or reencodes anything. ReStream rewrites the video as it changes the framerate for each frame. DVDPatcher is faster, and doesn't rewrite the entire video because (I think) it only rewrites a header.

[bobkart]

Yep, DVDPatcher seems to do the trick, thanks again.