[Cin] The best strategy to render yuv (mpeg, limited range) from yuvj (jpeg, full range)?

[Andrew Randrianasulu]

вт, 3 сент. 2024 г., 20:13 Tarantas via Cin <cin at lists.cinelerra-gg.org>:

> > > Since you're already fighting color banding, the good thing is to
> > > 32-bit colors in Settings -> Format -> Color model: RGB(A)-FLOAT.
> > > Note this could slow down your playback and rendering.
>
> Guys, hold on a second. Unfortunately I just discovered the RGB color
> model is required for this recipe. The YUV model causes big color
> shifts for an unknown reason. Moreover, I found JPEG mode completely
> incompatible with YUV color mode, even without any filters or hacks,
> and I lost the track of what's going on already.
>
> Must be just a bug because nobody tested JPEG mode in years.
>
> Could you please advise me any tool to detect shifts in color channels
> in order to compose a proper bug report?


one technique from

https://news.ycombinator.com/item?id=20037013

make all-white png in say gimp (so each point reads as 255 in all channels)
then convert it via tool in question (cinelerra-gg in our case) then
measure colour values during playback (via colorpicker).

it may be that bt709 conversion does not allow full range by definition?
(comment from that thread).

you can also try non-default pix-fmt (non yuv420p) for final encoding ?

cingg use 4:4:4 non-subsampled YUV in YUV mode, may be swscale lib having
trouble doing its job here?


All I could do now is just to
> screenshot the difference between the compose window and render results.
> --
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> Cin at lists.cinelerra-gg.org
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>
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