fps encoding question

[magnus]

I'm seeing all this talk about pulldown and inverse telecine and how lower fps give better quality with the same bitrate. I'm really trying to grasp this but need some examples. Say my source is 29.97 and I am encoding to SVCD, should I encode at 23.976 and use 3:2 pulldown playback option or encode at 29.97 with inverse telecine and 3:2 playback or just leave it as is at 29.97. What about a source of 23.976, just encode at 23.976 and use 3:2 playback option. I'm just a little confused here.

[FranckV]

I have been creating SVCD for a while now and you are right things are not always very clear and when you read things here and there, it is either innaccurate because written by user like me which base conclusions upon experience or incomprehensible because written by video engineers who like to make things sound complicated.

Here is what I think I know:

You need to know if you are making SVCD for TV playback or PC.

In case of TV, the TV set needs to receive 29.97 fps interlaced signal so this is what your DVD player must send the TV.

If the source is 29.97 fps interlaced movie, the simplest thing is to just encode it that way and that's it.

The thing is that it takes more space on the CD and it is harder to encode in MPG so in order to fit more on the CD and since the source is a movie you can IVTC it to get it down to 23.97 fps like the original theatrical movie was by getting rid of the extra artificial frames created by the 3:2 pulldown made for TV viewing.

If you encode the file that way you are saving 6 frames per second out of 29.97 (20%) of data i.e you can fit 20% more movie on the same CD (maybe even more since it is said it makes things easyer for MPG encoders).

Issue now is: can the DVD player play a movie coded at this rate ?
Mine does but it does not seem to be the case of all DVD players.

If yours does not or if you want to make sure you are creating SVCDs that you can play on other players, use the 3:2 pulldown when playback option in TMPGEnc, this sets flags in the MPG file telling the DVD player that it needs to recreate the 3:2 pulldown on the fly so that the TV can understand it (When encoding with CCE, Pulldown.exe used in DVD2AVI does the same thing).


Hope this helps

If anybody wants to either correct or comment, be my guest.