[FFmpeg-user] propagation of frames in a filter complex

Ted Park kumowoon1025 at gmail.com
Fri Apr 17 11:25:26 EEST 2020


>>> What do you mean?
>>> split[A]    select='not(eq(mod(n+1\,5)\,3))'       [C]interleave
>>>     [B]split[D]select='eq(mod(n+1\,5)\,2)'[F]blend[D]
>>>             [E]select='eq(mod(n+1\,5)\,3)'[G]
>>> I created the filtergraph by hand. I don't know what folks expect, but since duplicating pads (e.g., "[A] [A]") just takes up space, I didn't duplicate them. I don't know whether that relates to "reuse filter pad labels". Could you put some 'meat' on your 'bones'?
>> I meant using D twice.
> How would I use D twice? What do you have in mind? Can you draw a picture? I'm a picture-guy.
>> I thought it might create a cycle or something but since the first pair of [D] were linked to each other I guess that means you could use it again for blend's output pad.
> D already is 'blend's output pad.

I'm not really sure how else to put it, I think you might just be missing it because it's familiar to you. Anyway, it's not that important, but if you look at each pad in the diagram, D is used as the split filters' output pads before that, I was just commenting I didn't know you could connect an output pad, connect it to an input pad and then use the same label again later on.

>> For the actual filter though, should it look better on a 60Hz vertical refresh panel than 120Hz? I don't fully understand the rationale, but I was curious and tried it, on film material I can't tell the difference but animation looks horrible at 120Hz (like I'm dizzy, like a slow motion blur effect at regular speed?) but it's fine at 60Hz.
> A p24-to-p120 is a no brainer: 120/24 = 5, therefore, a simple 5x frame repeat. But what about folks who don't have 120Hz TVs?
> A p24-to-p60 is problematic: 60/24 = 2.5, therefore, a telecine.
> A p24-to-p30-to-p60 is a 23 pull-down telecine followed by 2x frame repeat. It's awful.
> A p24-to-p60 55 pull-down telecine is far superior, but players and TVs don't do that -- at least, MPV and/or my TV don't do it.

Yes, now I understand that it would reduce the stuttering you can get, I didn't know there were 60Hz display controllers that weren't capable of switching to 48Hz (and 96Hz for 120Hz displays) until recently. But I don't understand why the same 60fps result looks so much worse when the refresh rate is set to 120Hz. Maybe  it is because I am trying to view the filtered result in real time instead of writing to disk and playing.

Ted Park

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