1 Topic by pille (edited by pille 07-01-2023 15:28:53)

Topic: How exactly are non integer interpolation factors handled?

Hi,
I am currently using SVP to interpolate to 30fps (60 is too smooth for my liking) to not get judder and minimally smoother playback.

My projector only supports 60 or 30hz, not 48hz which is a shame. (custom resolution etc wont work either, it is a JVC X7900)

How is this non integer interpolation factor handled?

Scaling to 120fps then dropping/skipping frames as needed? (read that on this forum somewhere)

When using the "2m min artifacts" mode the wiki says that each original frame is used twice. So 24 frames repeated twice --> 48fps, then interpolation for 12 new frames? (for 60fps). Or 48 original frames and 72 new ones? (method above)
How about 30fps then?

I cant wrap my head around it.

Regards
pille

  • MAG79
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Re: How exactly are non integer interpolation factors handled?

> I am currently using SVP to interpolate to 30fps
> How is this non integer interpolation factor handled?

If we talking about createtion 30 fps  from 24 fps then every 4 frames must turn into 5 frames.
So, 1 frame is stayed untouched 3 frames are dropped, and 4 new interpolated frames are inserted instead of them.

> When using the "2m min artifacts" mode the wiki says that each original frame is used twice.
> How about 30fps then?

If we stil talking about 30 fps interpolation from 24 fps then:
- original pattern is 1234 (where 1, 2, 3, 4 - source frames numbers)
- uniform frame intepolation pattern is 1mmmm (where 1 - source frame, m - new interpolated frame)
- 2m interpolation mode pattern is 11234 (no new interpolated frames at all)

2m mode is useful for 60 fps from 24 fps intrpolation and any interpolation with factor more than x2.

Re: How exactly are non integer interpolation factors handled?

Thanks for your answer.

So 24 to 48fps using "2m min artifacts" actually does nothing except repeating every frame twice?

Re: How exactly are non integer interpolation factors handled?

not sure "1m"/"2m" do anything in 24->48 conversion

5 Reply by pille (edited by pille 10-01-2023 13:40:39)

Re: How exactly are non integer interpolation factors handled?

It sure does something with 1m, at least i can see artifacts.

So 24 to 30 just creates uneven frametimes (thus judder) with 2m Mode?

24 to 60 would be 11 22 33 44 nn (new frames) according top your Post above? No dropped frames after interpolating like in 24 to 30?

Re: How exactly are non integer interpolation factors handled?

24 to 60
"uniform": 1nnnn3nnnn5....
"2m": 11n22n33...
"1m": 1nn2n3nn4n...
something like this
"n" - interpolated frames, numbers - source frames

what exactly you'll get after enabling 1m/2m in any other XX fps to YY fps conversion - is a kind of mystery big_smile

7 Reply by pille (edited by pille 10-01-2023 14:29:24)

Re: How exactly are non integer interpolation factors handled?

Thanks for your patience.

"2m": 11n 22n 33n 44n 55n 66n 77n 88n 99n 1010n 1111n 1212 n1313n 1414n 1515n 1616n 1717n 1818n 1919n 2020n --> 60frames, 4 source frames missing?

This or sometimes 2 original frames after one another. e.g. 11n 22n 33 44n 55 66 77n ?



Well atleast from the wiki 1m should just each orignal frame ones. So for 24 to 48 it should be: 1n 2n 3n 4n 5n

Re: How exactly are non integer interpolation factors handled?

24 to 48 is _always_ 1n2n3n4n..., this is exactly why I said "not sure "1m"/"2m" do anything in 24->48 conversion"

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Re: How exactly are non integer interpolation factors handled?

> 60frames, 4 source frames missing?

No, "2m" will work as it should: every source frames showed twice. So, it will give you pattern 11n22 (five frames from two)

> "2m": 11n22n33...

here little mistake (typo). in case 24to60 fps it will be:
"2m": 11n2233n44...

> 1m should just each orignal frame ones. So for 24 to 48 it should be: 1n 2n 3n 4n 5n

You are right.

Re: How exactly are non integer interpolation factors handled?

So would it be possible to change the pattern for "2m" (24->60) to use 2 interpolated frames at once?

In the current state it produces uneven frametimes (11n22...) and thus judder.

Suggestion: 11nn22nn3344...

All frames are the same time so no more judder.

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Re: How exactly are non integer interpolation factors handled?

If you want to see every frame for two times just use fixed frame rate 30 fps: 24>30 fps
At screen of 60 Hz every frame will be shown twice.

12 Reply by pille (edited by pille 17-01-2023 17:30:08)

Re: How exactly are non integer interpolation factors handled?

MAG79 wrote:

here little mistake (typo). in case 24to60 fps it will be:
"2m": 11n2233n44...

Here you said 11n (one interpolated frame!) 2233n44....

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Re: How exactly are non integer interpolation factors handled?

what is your question?

Re: How exactly are non integer interpolation factors handled?

You explained that the 24 top 60 "2m" Mode creates uneven frametimes (i Said that several Times now).

Why isnt it handled in the way i described? 11nn2233nn...

The way you explained it: 11n2233...
1 frame schön twice, interpolated one once.

Or ist your later description correct? EVERY frame (interpolated ones aswell!!) is schown twice? So only 6 interpolated Frames , but shown twice.