120 FPS to 23.976 using Avisynth

[Zerox20]

This is always a nice forum topic. I would like somebody to explain something to me why the following processed worked for my conversion:

I have a 120 fps video, so I decided to use SelectEvery(5,0), so I do my standard 2 pass with xvid, and It comes out with Jerky Frames, OH NO! So I decide I will try changeFPS instead, so I implement that, however I just run it on the second pass and keep the same 1st pass stats file. The jerky frames were gone and it was running at perfect 23.976. I decided to investigate this more, so I ran a 2 pass encode with just ChangeFPS, and I get jerky frames. Based on what we know about fps and converting Doing selectevery for first pass and changefps for second pass should not even work and your bitrate would be all messed up, because of how each of the filters handle frames. So if somebody could explain to me exactly why this process worked, and my end product still looked very nice.

[haibane]

if u don't have to stick with avi.......
check out this thread.....
http://forum.doom9.org/showthread.php?s=&threadid=68562

[Zerox20]

Yep yep I have been there, I got that thread on my favorites actually! but I am just talking about avi for now =)

[clima]

I don't answer to your problem but I suggest you to use Decimate, it's slower than SelectEvery but better for avoiding jerkyness.

Decimate(4).Decimate(3).Decimate(2).Decimate(5)

As an explication :

3/4*119.88 fps = 89.91 fps
2/3*89.91 fps = 59.94 fps
1/2*59.94 fps = 29.97 fps
4/5*29.97 fps = 23.976 fps

See ya on #mf-sensei ;)

[Zerox20]

I've used decimate before too and it still happens, I want an answer to this question damnit! haha

[Mug Funky]

i'm afraid i have no idea as to why you were able to get 23.976 to play smoothly at all...?

the reason you get avis in 120fps is because that rate is a common denominator for 30 and 24.

if you decimate to 24, the 30 bits are going to jerk no matter what. this can't be avoided.

so i'd go back to that favourite thread i think...

that is unless your source doesn't actually contain anything but 24fps content... in which case the original video has a HUGE amount of wasted frame overhead (i really hate hybrid clips... it's not hard to master motion graphics in 24p dammit!)

[Zerox20]

Well my question still wasn't answered perhaps your right there was just a bunch of junk frames put in, I don't know. hehe

[mf]

Originally posted by Mug Funky
that is unless your source doesn't actually contain anything but 24fps content...
Which isn't that uncommon. I've seen anime eps that were totally 24fps but were authored to 120 anyway. I know it sounds stupid but I'd actually rather have those guys cap in 120fps anyway than get jerky stuff. It's no sweat to decimate it to 24fps so I don't care.

[Mug Funky]

heh. fair enough. it bothers me because i'm in PAL land and like to watch on teev.

it's a sorry mess that all these great animes come out with b0rked frame rates anyway. why not stick to 24? make it easier for us antipodes