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

[Andrew Randrianasulu]

вт, 3 сент. 2024 г., 21:10 Andrew Randrianasulu <randrianasulu at gmail.com>:

>
>
> 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?
>

I also found two possible sources of full range video -Playstation 5 (at
least back in 2023) and some GoPROs and other modern h264 based cameras

https://forum.shotcut.org/t/questions-about-color-range/38647/3

https://github.com/HandBrake/HandBrake/issues/2561


but may be sticking with artificial images is easier for debugging full =>
full encoding, then with full = > limited conversion step added on top of
that.


>
> All I could do now is just to
>> screenshot the difference between the compose window and render results.
>> --
>> Cin mailing list
>> Cin at lists.cinelerra-gg.org
>> https://lists.cinelerra-gg.org/mailman/listinfo/cin
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cinelerra-gg.org/pipermail/cin/attachments/20240903/3222cf89/attachment.htm>