difference between 23.976 and 29.976

[zappppp]

some ntsc dvds are encoded with 23.976 and some are 29.976.
whats the difference?why there's 2 settings for ntsc and 1 setting for pal?

[mpucoder]

Not to quibble too much, but it's 29.97. The reason is movies shot at 24fps can be encoded without converting to 29.97 by using some flags to get the DVD player to do the conversion (called pulldown). While the movie was shot at 24fps, it gets slowed down a small amount to make the conversion to 29.97 a rational one (5 NTSC frames for 4 film frames). 29.97 / 5 * 4 = 23.976
Native (camera) NTSC is left at 29.97

Pal uses 25fps for both, meaning movies run a little faster, or they get converted to 25fps by a process too complicated for a DVD player.