25 FPS m2v file plays perfect but after mux with BBMPEG not.

[GiantRobo]

I'm trying to convert 25 fps AVI (why do they make these?) to 25 fps MPEG2 so it plays correctly on my NTSC TV.

I gave up trying to create 29.976 FPS MPEG2 out of these 25 FPS AVIs.
Too much hassle getting audio to match up using CoolEdit

I used CCE to create a 25 FPS Mpv. I was surprised to learn that 25 fps Video plays perfectly on my NTSC TV. The only thing that matters is the resolution (I used 640x480).

Happily i tried to mux the mpv with the mp2 audio. Result is 25 FPS mpeg2 video with sound that matches but the video bounces ever so slightly and speeds up and slows down (again ever so slightly). WTH?

Can anyone help? I analysed the muxed MPeg2 and it is 25 fPs just like the m2v. Just have no idea why muxing it ruins playback.

[GiantRobo]

OK I give up. I just used TMPEG since I recovered its MPEG2 encoding. Nothing to think about. Just let TMPEG do the work.