Smoothness (fps)

[JP06]

If I watch commercial Xvid/DivX movies, they run smoothly at 25fps (or 23.97) but when I deinterlace my own DV-footage the picture comes jiggy (with 25fps).

Sure it runs smoothly if bob-deinterlaced to 50fps, but as those professional films can run smoothly at 25fps, it must be somehow possible with my DV-footage also?

[thetoof]

This is because the cameras used for professional film production is not DV. When they shoot, it's in 24 progressive fps (that is either telecined for NTSC, sped up for PAL or some other change to match the standard framerate of the region of the DVD release or the broadcast). Nevertheless, the origin is always at 24fps (except IMAX movies that are shot at 48fps). DV is shot at 30i (well, for NTSC), which could be considered as a way to display 60fps (it's actually not 60 fps, but 60 fields per second). With a mo-comped bobber like mcbob, you can actually have those 60 frames, but progressive. So, when you display that motion at the standard NTSC or PAL framerate, you are actually dropping some frames, which can result in jagginess.

Conclusion : bob deinterlace and keep that framerate to have your full "temporal resolution"

[2Bdecided]

Typical shutter speeds (e.g. 1/50th) on film at 24fps are slow enough to include motion blur which makes them look quite smooth. Not always though!

Typical shutter speeds on DV, especially in bright sunlight in full auto mode, are much faster (e.g. 1/120th-1/1000th). The result is usually acceptable at full rate (50fps), but if you drop every other image (to give 25fps), the result is visibly stuttery because the images don't merge together at all.

If you set your shutter speed manually to 1/50th, it'll look as smooth as film if you shoot in the same way as professional cameramen.

That last part is crucial: you don't see many movies shot with the camera waved around wildly and panning rapidly - but that's how most home movies are shot! That kind of movement can never look smooth at 25fps.

Cheers,
David.

[Blue_MiSfit]

well said!