120fps?

[Zarxrax]

Lately a lot of anime is being encoded as 120fps files. It looks like it is usually just 24 or 30 fps that has had MANY duplicate frames inserted. Does anyone know what the point of doing this is? Does this make it play smoother or something? Cause this is completely baffling my mind why these people are doing this, and its a pain to try and convert it back down to a good framerate.

[DJ Bobo]

Hmm.. I don't think serious people will release 120fps videos, it's just too much.
There is no logical explanation for this, it's just some fools trying to act cool.
If I was you I would delete those crap files immediately and get the DVD or get another decent file.

[EDIT]
You can of course decimate these files by 4 to get 30fps or by 5 to get 24fsp without having to recompress (in VD, check Video is on direct stream copy and setup the decimation under Frame Rate, and save to a new AVI)

[wmansir]

I may have read something about this, but I can't recall where. The reasoning was the same as when, instead of deinterlacing video people seperate the fields and encode at 60fps, you get smoother playback.

But if the video is a mix of 24fps and 30fps you need to find a rate that they both divide into. so you go to 120fps (24x5,30x4). I imagine it only works at low resolutions, because it's pretty demanding on the system.

[MvB]

@wmansir

i think you read it here:

http://www.100fps.com

[Zarxrax]

Simply decimating does not work. When I doecimate by 4, I get a very choppy AVI playing at about 1/4th normal speed.

[Zarxrax]

Actually I guess the speed is correct, its just really really choppy. Looks like its running at like 4fps. Also the filesize went from 121mb down to 42mb when I decimated.

[DJ Bobo]

That's weird.
And through 2? and 5?

[Guest]

If you really are just removing duplicate frames and then adjusting the frame rate, then it should not come out jerky.

[Zarxrax]

The 120fps source video has 2 parts, a 30fps section and a 15fps section. I can tell this because in the 30fps section out of every group of 4 frames, the first of them is a new frame, and the next 3 are just duplicates of it. In the 15fps section, its the same, except there is only a new frame in every group of 8.

When I decimate by 4 in virtualdub, it results in a 29.97fps video, but here's what happens. In there 30 fps section, it STILL only has 1 original frame out of every group of 4, and the rest are duplicates! Then in the 15fps section, there is still only 1 original frame for every group of 8!

[wmansir]

You could try the Decimate fucntion form the avisynth plugin Decomb. It actually compares frames and attempts to remove duplicates. It's normally used for IVTC, so it removes 1 in every X frames, you will have to run it a couple of times to remove so many duplicates.

so, if you wanted to keep 1 in 4 frames try:

LoadPlugin("C:\myplugins\Decomb.dll")
AviSource("c:\mymovie\myavi.avi")
Decimate(cycle=2)
Decimate(cycle=2)

[Neo Neko]

Originally posted by MvB
@wmansir

i think you read it here:

http://www.100fps.com

Yeah that guy is rotting peoples brains and his converts are rabbid. There is a tiny bit of creedence to what he says though. But he and his followers treat it as the supreme rule. I had a runin with a believer recently.

The only place converting fields to frames is advisable is on cheap home DV material. Pro DV equipment used in television and movie production behaves differently. They can record at several different frame rates interlaced or progressive. The only catch on TV sources are the tickers at the bottom on channels like fox news etc. For some reason these professional stations broadcast propper recorded true interlaced material with overlayed graphics at a different frame rate. ACK!

The aplication of this guys doctrine to anime has got to be the most ignorant step thus far. Anime is at best 29.97fps(CG sceens mostly) and almost always 24fps(high quality movies), and quite often 12fps(TV series like DBZ and pokemon. Actually pokemon looks to be 6fps. really bad stuff).

The 100fps doctrine is all about lazyness and never having to learn how to deinterlace correctly.

[theReal]

I don't think the guy (don't know his name, sorry) at 100fps.com ever said you should encode at 100 or 120 fps. It's 50/60fps that he's propagating, don't know why he called his site 100fps...

I found that sometimes using 50fps for tv captures or DV recordings can improve the look of fast movements - but I never really use it because the bitrate is just getting too high and the cpu power needed is also pretty high.

For most DVD's, especially anime or cartoons, 50/60fps is total overkill because a frame rate of 25/29.97 fps is already higher than needed for a cartoon. I've seen Simpsons episodes that were encoded at only 15fps and you didn't notice a difference to my 25fps tv-captures - I guess you need to decimate the framerate correctly to achieve that result, but it shows that for cartoons even less than 25fps can be sufficient.

[Tri]

The guy on 100fps is talking about PAL and not NTSC. Using 50 fps for PAL can be a good idea when capturing because it's interlaced then.

Capturing Anime with 120 fps is stupid IMHO because Anime is usually telecined to 29.97 fps and not purely interlaced. What's the point in capturing at 120 fps then? :confused:

[Zhnujm]

i have searched long for a good deinterlacing method and the field splitting gives the best results for me. dont see why this should be so wrong.

and no, i have not read his (or her ?) site before ;)

[Tri]

Originally posted by Zhnujm
i have searched long for a good deinterlacing method and the field splitting gives the best results for me. dont see why this should be so wrong.

Speaking about (most) Anime this is not true. Most are telecined from 23.976 to 29.97 fps and the only correct way is to do IVTC to have the original 23.976 fps (This is what I've learned in this Forum =) ). I don't know about other NTSC sources ;)

[Zhnujm]

of course i was only speaking of pure interlaced material.
if its not interlaced, dont deinterlace it. ;)