[Cin] Clipping to 1.0 investigation.

Andrew Randrianasulu randrianasulu at gmail.com
Thu Nov 9 15:10:26 CET 2023

чт, 9 нояб. 2023 г., 13:37 Andrea paz <gamberucci.andrea at gmail.com>:

> As usual, I didn't quite understand the opengl patch (should I use
> only the second one?). How does it work?

well, it puts internal buffers to textures, tell gpu to perform some shader
based operations on them, then either reuse results for next stage or send
to display. For rendering unlipped values above 1.0f one need to set both
textures and gpu colorbuffers (off-screen ones at least) to fp32 format.
Shaders work by default in fp but some may contain internal clipping (will
try to remove that too). My test case was putting your uber EXR over
timeline with simple 100 - 0  fader. Default 8bit textures fade it to dull
white, 4x bigger 32f textures nicely unveal overly bright areas as fade
progressed. But color picker still was saying 1.0.in most bright areas, so
some clipping was still around with vo opengl. I just wanted to say I never
tried to fade such file before, so I never saw this effect with my own
eyes. Provided me with a bit of reason for continue to try and get full
opengl 32f pipeline running ( I asked question on our big black russian
forum, may be some real developer will answer).

But if you stick to x11 vo you can ignore opengl patch and only try patch

> I have tried to install CinCV without success. Some time ago I tried
> to install CinHV but still without success. I didn't quite understand
> if on CinCV histogram is clipped or not.

well, in my case not, it goes above 100, while I think our videoscope not
quite designed with full hdr in mind. Will try to locate pictures of more
hdr aware editors to see how it might be done ... Also, while colorpicker
in CV looks much more primitive it still works with over 1.0f values, so
you can use it instead/in addition to vectoroscope/videoscope plugin.

Can you post cincv build error? It builds on slackware 15.0 i686 .... Are
you using latest git or release? Release was busted by gcc changes ....

Where can I find the older versions of CinGG?

whhhhm. I just canned them to live dvd images of my system I was doing
periodically, so they on physical dvd disks (and each image is like 2-3 Gb
big). One can try to install say ubuntu 14-16 on qemu or other virtual
machine and then compile cingg history git snapshot there ...

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