Unusual framerate conversion

[Doomed Space Marine]

Hi,

I have recently started to reencode some of my divx anime episodes which I had trouble viewing because of the TVs overscan, cutting off subtitles.

I resolved that issue with the following script.
AVISource
LanczosResize(608,400)
AddBorders(56,32,56,48)

Unfortunately, some of the episodes have very high framerates. And a large amount of frames. Although the episodes are all approx. 23 min.


Here is a gspot screen of one of the odd episodes. I tried adding AssumeFPS 23.976 to the above script but the result stuttered and didn't playback smoothly. I'm confused on what I should do, I haven't had a problem like this before.

Thanks ahead of time.

[jimmalenko]

I tried adding AssumeFPS 23.976 to the above script but the result stuttered and didn't playback smoothly. I'm confused on what I should do, I haven't had a problem like this before.

By my calculations, 119.89 is pretty damn close to 29.976 * 4. Try Assume FPS 29.976 and see how you go.

[Doomed Space Marine]

Ok Jim thanks for the quick reply! I will give what you said a go.

[Doomed Space Marine]

Hmmm how troublesome. Using a framerate of 29.976 the video plays to slow compared to the source. It's getting closer to being right. Thanks for helping. Any other suggestions?

[JamieBecks23]

25?

[Doomed Space Marine]

Wouldn't 25 fps just make the video play even slower than 29.976? I need the video to play somewhat faster than 29.976 it seems. I tried processing every third frame that seems to be getting good but it might be a bit too fast. Thanks for the input Darth. Any other ideas?

[Gillies]

its not some weird progressive scan format is it?

[jimmalenko]

There's one thing here that is puzzling me ...

I have recently started to reencode some of my divx anime episodes which I had trouble viewing because of the TVs overscan, cutting off subtitles.

How have you been watching them on the TV ? Video out from the computer ? DivX player ? Previously convterted to VCD/SVCD/DVD ?

When you were getting the overscan problems, was the motion smooth then ?

[Doomed Space Marine]

Oh, I apologize for not giving you guys the whole picture I am watching them on my dvp-642. These videos were originally divx files. Some divx3 some divx5 it varies. All the episodes play just perfect except these two (ep 34 & 35). Which have abnormal (to me at least) framerates. I am pretty sure I didn't have motion issues when I had overscan troubles. The only issue was not being able to see the subs. As for your question Gillies I am not sure. It's nice to see people trying to help me out I appreciate it!

[manono]

Hi-

Often anime raws are at 119.89fps because it's a common multiple of 23.976 and 29.97fps. So, evidently there's a mix of 24fps film and 30fps, probably CGI, perhaps in the opening, and maybe scattered around the episodes.

As you discovered, Jim's AssumeFPS(29.97) stretches the video to 4 times its original length, without cutting out any of the duplicate frames. He may have meant to say ChangeFPS(29.97).

However, ChangeFPS is a "dumb" form of decimation. Something like:

Decimate(2).Decimate(2)

from Decomb should work better. Even better (and faster) might be:

SmartDecimate(4,32)

There will still be duplicate frames during the film parts, but it should play fairly smoothly. Try them out to see which works better.

[jimmalenko]

As you discovered, Jim's AssumeFPS(29.97) stretches the video to 4 times its original length, without cutting out any of the duplicate frames. He may have meant to say ChangeFPS(29.97).

essentially, yes.

Any decimation of frames will affect the fluidity of movement, unfortunately

[Doomed Space Marine]

Hey Manono and Jim. Thanks for the advice I will give your suggestion a try, Manono, and see what happens. Its weird though about ten of the episodes have the same intro (possibly cgi effects like you said) and they work with no problems and have normal framerates. I didn't know you could mix framerates 24 and 30 in the same video if thats what you mean. I don't know much about this though so it doesn't surprise me that I haven't heard of it, heh. One question will the video suffer in quality dramatically no matter what I do to it?

I will post my results after I get home from school. Thanks again guys!

[manono]

Hi-

Lots of anime these days have at least some 30fps stuff. There's usually so little of it that I much prefer to get it back to 23.976fps. That will spread
the available bits among fewer frames, resulting in higher quality.

Yes, it's very possible to mix film (24fps) with video (30fps) in the same DVD. The film parts will have been telecined to output 29.97fps. You IVTC to return
it to 23.976fps.

It's possible to get it to 23.976fps or to 29.97fps with no quality loss at all. It depends on whether or not ChangeFPS works. It might. I'd first open the 119.89fps
AVI in Nandub. Set both Video and Audio for Direct Stream Copy. Then go Video->Frame Rate->Frame Rate Decimation->Decimate By 4. Then save it under a
different name. Check it out for smoothness. That will give you 29.97fps. If that checks out, then do it again, Decimating by 5 this time. Save it
again and check for smooth playing. That will give you 23.976fps. If there isn't any 30fps stuff, or very little, or it's going by so fast that you can't
tell there are any frames missing, that could very well work out OK.

Otherwise you'll have to reencode with a resulting quality loss. However, based on that GSpot pic, the quality must suck to begin with.

[Doomed Space Marine]

Manono,

What you said works like a freakin' charm. ChangeFPS(23.976) makes things run nice and synched up with the original. I will have to remember that command for the future that way I don't bug everyone asking how to fix that issue, heh. Thanks for your superb help, Manono. Jim I thank you as well for your help (you were on the right track it seemed like) and everyone else. This is truly the best place to ask for help regarding video stuff.

As for the quality of the episodes, they look pretty good on my computer but on my tv they dont look as nice so I have been raising their bitrate to a 2 pass 1500kbps using divx 5. That seems to help. Maybe you have a better suggestion, I'm always open to trying a different technique that would work better.

[manono]

Thanks for reporting back, Doomed Space Marine. A couple of times recently some advice I gave didn't work out for one reason or another.
So it's nice when it works out OK. A little positive reenforcement always helps. And I'm happy you got it sorted out.

About the quality; The pic says they're 640x480 with a bitrate of 853. That just seems too low to me, even taking into account all the duplicate
frames from the 119.89fps, and the dupes that anime has anyway from large parts of them being drawn at 16, 12, or even 8fps. Ordinarily, for
that bitrate, I'd make mine for 512x384. But maybe your series doesn't have a whole lot of action, or maybe the encoder made judicious use of
filters to make the episodes more compressible. You might try and run them through DRFAnalyzer to check the average quants. You might pause
during the action scenes and look for mosquito noise and/or blocking.

I'm a bit leery about reencoding AVIs, as it's real difficult to improve on the source. If you had the source DVDs, then there are lots of things you
could do. Anyway, good luck.