Mpeg 4 29.97fps to Mpeg 2 23.976fps

[Waylander076]

All

I have a Divx 5 video encoded at 29.97fps.
I want to convert it to NTSC DVD so I need to Inverse Telecine
it first to get a video file at 23.976fps then run pulldown on so
it plays back at 29.97 fps.

The question is can an Mpeg4 video file be inverse telecined in the same
way a 29.97fps Mpeg2 file can?

Can I run it through Vdub to create a 23.967fps AVI and encode that
as Mpeg2 and then run Pulldown on it?

Thanks for any help.
Waylander

[DJRumpy]

You can run inverse telecine on any type of video, including MPEG4, assuming of course, that the source is telecined. If the source is NOT telecined, the you will only end up destrying frames, and giving the video a jerky appearance.

You have verified that your source is telecined, and not true 29.97 interlaced, right?

[FOO]

Another question, slightly off topic, is whether Mpeg4
supports soft telecine. I guess I need to look up Mpeg4
as it seems 90% of the posts these days are about it.

[Gazorgan]

Good luck. Your wanting to take a 29.97 progressive encode, IVTC it to 23.97 progressive, Re-encode it to 23.97 interlaced, then play it on your DVDplayer as 29.97.

I think you will be better off quality wise to leave it 29.97. The bitrate you gain for encoding at 23.97 over 29.97 is going to get wasted in bad frames from IVTC most likely(depends on the movie, some are mixed and need a real smart IVTC routine). If it's letterboxed don't bother, it's not worth the bitrate savings.

My Film DVD-DivX backups are 23.97. I don't think I've ever made a 29.97 backup on purpose, there's no point unless the DVD is 29.97 to start.

[FOO]

Good luck. Your wanting to take a 29.97 progressive encode, IVTC it to 23.97 progressive, Re-encode it to 23.97 interlaced, then play it on your DVDplayer as 29.97.

How do we know it's a progressive encode ? Because it's not MPEG2 ?

[Gazorgan]

DivX doesn't do interlaced.

[DJRumpy]

Actually, DivX does support interlaced material. Newer versions (5+) handle interlaced video without issue.

As far as IVTC, done properly, it is well worth the exorcise. Not only do you return your video to it's original framerate, you also gain bitrate from the reduced framerate which can be used to increase the quality of your final encode. In addition to that, the fact that your encoding progressive frames is also a plus. Progressive material is inherently easier to encode than interlaced material.

How do we know it's a progressive encode ? Because it's not MPEG2 ?

The format the video is in is irrelevant. MPEG-2, MPEG-4/AVI, etc. aren't specific to either interlaced or progressive. Unless the format is specifically designed to produce a specific format (DV Video is a good example..it's interlaced as a rule), your video could be either type (Progressive, Interlaced, or Telecined). Standard DivX/XviD encodes can be any type, as can MPEG-2 encodes. You need to verify before performing IVTC. If it is telecined, you should definately perform IVTC.