NTSC frame rate - which one?

[dave_c]

i'm confused - ntsc apparently has two frame rates it can support.

when you're converting from pal to ntsc, which frame rate do you convert to? 23.976 fps or 29.976 fps? this is pal to ntsc dvd, btw.

[adam]

There is only one supported playback rate for NTSC and that is 29.97fps. But it is much more efficient to store the video at 23.976fps and let the hardware player convert it to 29.97fps. This is the preferred method of storing NTSC footage, and is how the vast majority of NTSC DVDs are made.

So, with a progressive PAL source you'd always want to simply slow both the audio and video down to 23.976fps. Then apply pulldown flags (most encoders have a 3:2 pulldown option or you can use pulldown.exe after encoding) and it will playback at 29.97fps.