25 fps better than 24.975?

[rotflol]

Hello,

Here's another stupid question from me:

Under PAL TO NTSC, the IVTC guide (http://www.doom9.org/ivtc-tut.htm#IVTCForNTSC) says,
This returns it to 24.975fps with the audio still in synch. If you wish to make it 25fps, then add AssumeFPS(25) at the end.

Should I wish to make it 25 fps rather than 24.975? Does it make any difference?

[jggimi]

This technique is to "repair" a PAL -> NTSC video transfer, for display on a progressive device (such as a PC monitor).

If your display device is a PC, then you can leave the framerate untouched.

If your display device is a standalone player, it will depend upon the player's capability to manage either 24.975 or 25 fps, if at all. Unfortunately, I don't have a standalone MPEG-4 player. I assume for standard interlaced NTSC televisions -- and I may be wrong -- that it would need to display 59.94 fields per second, and will telecine any 24fps MPEG-4 video, or play any 29.97fps video as 59.94 fields per second.

[echooff]

Souldn't that be 23.975 for ntsc

[jggimi]

No, you are thinking of Inverse Telecined 29.97 video, which has a framerate of 23.976fps. This procedure is for 25fps PAL video that has been converted to 29.97, not for 24fps film.

The process for returning PAL->NTSC video transfers to progressive uses Telecide(Guide=3).Decimate(6), and converts 29.97 to 24.975 fps.

See the IVTC tutorial .. specifically the section mentioned in the first post of this thread. Note that the syntax for Telecide has changed since it was written (order=0 or order=1 must be added).

[echooff]

Thanks.

[rotflol]

Originally posted by jggimi
This technique is to "repair" a PAL -> NTSC video transfer, for display on a progressive device (such as a PC monitor).

Yes, that's exactly what I'm trying to do. :)

If your display device is a PC, then you can leave the framerate untouched.

That is the case, thank you.

If your display device is a standalone player, it will depend upon the player's capability to manage either 24.975 or 25 fps, if at all. Unfortunately, I don't have a standalone MPEG-4 player. I assume for standard interlaced NTSC televisions -- and I may be wrong -- that it would need to display 59.94 fields per second, and will telecine any 24fps MPEG-4 video, or play any 29.97fps video as 59.94 fields per second.
I see. There is a slight possibility that the video might someday be watched on a standalone, but what the hell. Let's hope players can cope with this. BTW, I suppose this framerate difference can be handled during conversion to (S)VCD?

[jggimi]

SVCD and VCD have specific framerate requirements. See www.vcdhelp.com for specifications.

[manono]

Hi-

I just don't like the looks of 24.975fps, so I return them to 25fps. It doesn't make any difference, really, except for the audio having to be stretched if you decide to go for 25fps. My standalone will play any framerate, but I don't know if that's true of all of them. Heck, I don't even like 23.976fps, but that's the way they come out of a DVD player because it has to conform to the NTSC TV specs, even though they're usually stored on the DVD at 24fps. But I'm too lazy to change all my 23.976fps encodes to 24fps.

SVCD is another thing entirely. For PAL, they'll have to be 25fps. For NTSC they'll have to be 23.976fps, 24fps (with pulldown applied after either of those 2), or 29.97fps.

[rotflol]

Thanks, guys. I am aware of the framerate restrictions for SVCD, I wanted to be sure if the conversion to a compliant framerate is doable during the conversion of this avi to (S)VCD, maybe VDub with an appropriate Avisynth script could serve frames with the corrected framerate to TMPGEnc or whatever. It's not a concern for me, I don't do SVCDs, I just wanted to know. :)