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

[Mark Filipak]

Hey, Ted,

On 04/17/2020 03:52 AM, Ted Park wrote:
> Hi,
> 
>> 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.

> 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.