(23,976 fps) AND 29,970 fps

[greendesert]

What would be the resultant quality difference in the video encoded file if encoded at NTSC (23,976 fps) AND 29,970 fps ? Does the selection depend on the source file ??

[manono]

Hi-

Does the selection depend on the source file ??

Yes. If the true framerate's 23.976fps and you encode at 29.97fps, not only have you encoded 25% more frames unnecessarily, with the resulting quality degradation for a given file size, but depending on how you add in those extra frames, it'll look various degrees of bad. If the true framerate is 29.97fps and you encode it at 23.976, then you're missing 20% of the frames, and it'll play jerky. This answer is kind of obvious, so it may not be exactly what you had in mind
.

[edDV]

720x480/23.976p is progressive video at film frame rate. It is the only allowed 720x480 progressive frame rate for NTSC DVD.

720x480/29.97i* is normal interlaced video. Progressive Film can be converted to interlace video through a "telecine" process. Likewise, film based interlace video can be converted back to progressive 23.976 frame rate through a process called "inverse telecine".
http://www.dvdfile.com/news/special_report/production_a_z/3_2_pulldown.htm

720x480/23.976p is most often used for film based DVD recording. A normal DVD player applies the telcine conversion internally and outputs at 29.97i over composite, component or S-Video.

Progressive DVD players in progressive mode will frame repeat 720x480/23.976p in a 3 then 2 sequence to output at 720x480/59.94 progressive frames per second over the analog component or DVI outputs to a progressive TV.


* other allowed NTSC DVD resolutions
704 x 480 pixels MPEG2
352 x 480 pixels MPEG2
352 x 240 pixels MPEG2
352 x 240 pixels MPEG1