[Cin] psychtoolbox vs HDR

[Phyllis Smith]

What an interesting name!

On Wed, Jun 7, 2023 at 8:05 PM Andrew Randrianasulu via Cin <
cin at lists.cinelerra-gg.org> wrote:

> Found this tidbit
>
>
> http://psychtoolbox.org/news.html
>
> in 3.0.18 beta
>
> 16 bit native (effective 12 bit) framebuffer support for Linux with AMD
> Polaris and later.
>
> ====
>
> This commit switches PsychImaging() to only expose 16 bpc framebuffers on
> such Linux + X11 + AMD Polaris+ + amdvlk + Linux 5.14 systems, but then at
> much better reliability and performance than our old dead code.
>
> It allows to get up to 12 bpc per color-channel color output, ie. 4096
> intensity levels for red, green, blue, grayscale/luminance and a total of
> 64 billion shades of color, either on suitable 12 bpc capable high-end
> displays, or via spatial dithering by the gpu on the more common 10 bpc
> capable displays or even - at a lower quality - standard 8 bpc capable
> displays.
>
> This makes Linux the first operating system to my knowledge to support
> this color precision on out of the box on commodity graphics hardware and
> displays, natively at full performance without any compromise in timing
> precision or reliability.
>
> Basic testing has been performed with a CRS ColorCal-2 on a HDR-10 10 bpc
> capable monitor and on a MacBookPro 2017 Retina display under Linux, with
> AMD RavenRidge and Polaris.
>
>
> ====
>
>
> test apps apparently even include gstreamer-based movie player (never
> thought I'll find HDR player in medical software ...)
>
>
> http://psychtoolbox.org/docs/PsychHDR
>
>
> http://psychtoolbox.org/docs/PlayMoviesDemo
>
>
> ===
>
> If the optional flag ‘hdr’ is specified as non-zero, then the demo
> expects the onscreen window to display on a HDR-10 capable display device
> and system, and tries to switch to HDR mode. If the operating system+gpu
> driver+gpu+display combo does not support HDR, the demo will abort with
> an error. Otherwise it will expect the movies to be HDR-10 encoded and
> try to display them appropriately. A flag of 1 does just that. A flag of 2
> will
> manually force the assumed EOTF of movies to be of type PQ, iow. assume
> the movie
> is a HDR-10 movie in typical Perceptual Quantizer encoding. This is useful
> if you
> want to play back HDR content on a system with a [GStreamer
> <http://psychtoolbox.org/docs/GStreamer>](GStreamer)
> <http://psychtoolbox.org/docs/%28GStreamer%29> version older than
> 1.18.0 installed, where [GStreamer
> <http://psychtoolbox.org/docs/GStreamer>](GStreamer)
> <http://psychtoolbox.org/docs/%28GStreamer%29> is not fully HDR capable,
> but this hack may
> get you limping along. Another restriction would be lack of returned HDR
> metadata,
> so if your HDR display expects that, you will not get the best possible
> quality.
> Upgrading to [GStreamer <http://psychtoolbox.org/docs/GStreamer>]
> (GStreamer) <http://psychtoolbox.org/docs/%28GStreamer%29> 1.18 or later
> is advised for HDR playback.
> A flag of 3 or 4 will use an alternative HDR display method only available
> on
> Linux/X11, with 4 applying the same hack to cope with older [GStreamer
> <http://psychtoolbox.org/docs/GStreamer>](GStreamer)
> <http://psychtoolbox.org/docs/%28GStreamer%29> versions
> as a setting of 2.
>
>
> ====
>
>
> happy psyching! (???)
> --
> Cin mailing list
> Cin at lists.cinelerra-gg.org
> https://lists.cinelerra-gg.org/mailman/listinfo/cin
>
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