Framerate Conversion

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popeye13
Posts: 19
Joined: Sat May 24, 2014 2:40 am

Framerate Conversion

Post by popeye13 »

I was told the framerate conversion algorithm is very basic so i suggest a better one that doesn't cause stuttering when changing a lower framerate to a higher one (Such as 23.976 to 25)
Woodstock
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Joined: Tue Aug 27, 2013 6:39 am

Re: Framerate Conversion

Post by Woodstock »

What algorithm would you suggest? "A better one" isn't very specific.

Oh, and to quote others, "Patches Welcome".
GregiBoy
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Joined: Sat Feb 12, 2011 9:23 pm

Re: Framerate Conversion

Post by GregiBoy »

Why do you want to change frame rate anyway?

Most modern players and TV's will handle this for you.
popeye13
Posts: 19
Joined: Sat May 24, 2014 2:40 am

Re: Framerate Conversion

Post by popeye13 »

Woodstock wrote:What algorithm would you suggest? "A better one" isn't very specific.

Oh, and to quote others, "Patches Welcome".
Oh im sorry, i thought this was a suggestion forum. I didn't realise i had to satisfy you too!!!
Woodstock
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Re: Framerate Conversion

Post by Woodstock »

Not a case of satisfying any particular person.

However, asking for "something better" without suggesting something that is better is exceedingly vague. Some of the things that would be "better" are not available under the source licensing being used for Handbrake.

If you know of something better, suggest it. If you don't, do a bit of research to see if there is something, and suggest it.

In this case, however, it would have to be something very smart, because you're asking it to chose one frame out of 24 to insert to make 25 frames in a second, all while not affecting the smoothness of motion. To truly be smooth, you would have to take those almost-but-not-quite 24 frames, and use them to construct 25 NEW frames, averaging the motion of objects across them.
Djfe
Bright Spark User
Posts: 178
Joined: Tue May 13, 2014 8:01 pm

Re: Framerate Conversion

Post by Djfe »

some interesting looking ones that I found:
http://www.ee.cityu.edu.hk/~lmpo/public ... VT_4SS.pdf

http://www.snellgroup.com/documents/whi ... _Paper.pdf
http://www.snellgroup.com/documents/eng ... motion.pdf

https://www.google.de/search?q=frame+ra ... +algorithm

someone would need to ask the author(s) though if he's allowed to write a code based on this algorithm and publish it as open-source
Deleted User 11865

Re: Framerate Conversion

Post by Deleted User 11865 »

Djfe wrote:someone would need to ask the author(s) though if he's allowed to write a code based on this algorithm and publish it as open-source
We could as a courtesy, but unless it's patended I don't think we need to.

Anyway, I have no personal interest in adding such a feature, sorry.

We will accept (good) patches though.
Deleted User 13735

Re: Framerate Conversion

Post by Deleted User 13735 »

Frame rate conversion, other than by drop/dupe (which Handbrake already supports), involves very complex resampling algorithms.
A good one is Twixtor. Depending on your editor, it starts at $300+.for the plugin.
TedJ
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Re: Framerate Conversion

Post by TedJ »

To be honest, the usual method for 23.976 -> 25 fps conversions is to overcrank it - assuming you apply pitch correction the only side effect is reducing the running time of the title by ~4%. This is common practice for PAL DVD releases.
Deleted User 13735

Re: Framerate Conversion

Post by Deleted User 13735 »

Completely true.
90%+ of PAL movie releases are done this way.
Often the audio is just resampled without any pitch correction.
TedJ
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Re: Framerate Conversion

Post by TedJ »

Yup. You're only looking at a semitone difference so most people won't notice it unless they do a side by side comparison.
Deleted User 13735

Re: Framerate Conversion

Post by Deleted User 13735 »

I grew up in an era when vinyl recordings were sped up a semitone to mask wow and flutter. Really hard to learn songs on piano in seven sharps (C#).
F J Walter
Posts: 18
Joined: Tue Jul 29, 2014 4:08 am

Re: Framerate Conversion

Post by F J Walter »

TedJ wrote:To be honest, the usual method for 23.976 -> 25 fps conversions is to overcrank it - assuming you apply pitch correction the only side effect is reducing the running time of the title by ~4%. This is common practice for PAL DVD releases.
It's not just common, it's universal. There is no other way (except for some anime).

Also, pitch correction has the potential to decrease sound quality in negative ways. Usually, the sound is just stretched, leaving it almost a semitone higher. This is no more noticeable to audiences than the 4% faster pacing.

Given that we in PAL-land don't need 3:2 pulldown and we got a better colour system and frame resolution, I can live with the 4% speedup for 24p movie content. Blu-ray is making that moot nowadays anyway.
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