Sony Megatron Colour Video Monitor

[MajorPainTheCactus]

Not at all thank you for your guidance and patience!

I’ve got to go to sleep now but very quickly with respect to 2800 - it’s an offset of the white point for the CRT color systems white point so PAL, NTSC-U D65 and NTSC-J D93.

As @rafan I think pointed out above my PVM has a white point of D93 so I have to add 2800 to the D65 temperature of NTSC-U to get the right look i.e 6504 + 2800 = 9304 which is one below D93.

Also there’s just one shader - SDR/HDR is switchable in the shader - I think the RT format doesn’t matter as it’s a UNORM and as long as I don’t write over 1.0 to it it all works out because the back buffer is the standard 8888_UNORM I think. It seems to work at least.

[MajorPainTheCactus]

@HyperspaceMadness

What is the difference visually for you on your on your screen between the HDR version and SDR Version?

A slight reduction in brightness - I’m not sure what the peak luminance is in SDR mode for my monitor but it’ll probably be less than the HDR mode. That’s all just guesses though.

@HyperspaceMadness

I’m also curious what this will look like on OLED since on OLED the whole backlight wouldn’t be cranked up like on an LCD.

The main problem with OLEDs are the WRGB layout - it just ruins the look of the shader AFAIK. I’d love for people to try again but fundamentally you can’t remove the W elements which a CRT never had. This effects all shaders though and people seem to have been happy with the image so all this is subjective. Again I’d love to hear what peoples experience is of this in SDR mode on these displays (I don’t have access to an OLED).

P.S. QD-OLED displays will be fine because they have a RGB sub pixel layout.

[MajorPainTheCactus]

@HyperspaceMadness

Maybe you will want to come up with a new awesome name for your shader since there will be hdr and sdr versions of it?

Yes! People have been saying that.

[MajorPainTheCactus]

Rename is done! See top/first post for videos and a bit of tongue in cheek fun.

[HyperspaceMadness]

Nice!

[Nesguy]

Just to take stock of what the shader can currently do:

-Pro-grade aperture grille
-consumer-grade aperture grille (just use the 8K mask at 4K)
-Pro-grade slot mask
-High-res dot mask

What’s still missing:

-consumer-grade slot mask (most common mask used in TVs, only mask used by arcade CRTs)
-low-res dot mask (used by early computer monitors)
-color grading stuff 

Further down the road?

-composite video signal stuff

@MajorPainTheCactus

[Nesguy]

How does black light strobing compare to software based black frame insertion at 120Hz? I remember the software based BFI used to be better for some reason, but that was years ago.

[MajorPainTheCactus]

@Nesguy

-consumer-grade slot mask (most common mask used in TVs, only mask used by arcade CRTs)
-low-res dot mask (used by early computer monitors)
-color grading stuff 

Hi @Nesguy so I thought I’d just focus on what’s missing.

So I’ve added a whole load of colour grading stuff - input colour systems, output colour spaces, phosphors, contrast, brightness, saturation, temperature. I want to add tint. I dont see the benefit of hue. What would you like to see/think is missing?

What do you mean by consumer-grade slot mask? The mask I’ve got seems to match all the ones in my local arcades although I could be missing something.

I do have low res for mask - I think the Toshiba preset is currently set to use it (not that it should). But it may not be what you are after.

We can do anything you want supported basically. Currently I’m doing an optimisation pass as the colour grading stuff has made things SLOW (still faster than most shaders but not as fast as it was).

[MajorPainTheCactus]

I can’t imagine software based BFI being better than blacklight strobing as you just don’t have the control that the monitor has. Blur busters implemented the backlight strobing on the Eve Spectrum and gives different strobe lengths and a custom app to tweak it. As I understand it, it’s far closer to how a CRT refreshes the screen than bluntly adding a whole black frame. Blur busters say they think the they’ve achieved Plasma level blur reduction. I’ll get a video to show you and you can hopefully judge for yourself to some degree.

[Nesguy]

@MajorPainTheCactus

So I’ve added a whole load of colour grading stuff - input colour systems, output colour spaces, phosphors, contrast, brightness, saturation, temperature. I want to add tint. I dont see the benefit of hue. What would you like to see/think is missing?

I actually haven’t taken a look at the latest, but sounds like you’ve done a good job here.

@MajorPainTheCactus

What do you mean by consumer-grade slot mask? The mask I’ve got seems to match all the ones in my local arcades although I could be missing something.

The slot mask photos I’ve seen thus far are of a medium-high TVL slot mask monitor, most likely a 31kHz monitor that’s designed to handle multiple resolutions and such.

A typical 15kHz arcade monitor or TV is lower res than this, it has maybe 1-2 triads per picture line as opposed to 2-3,.

Are most of the machines at your arcade of the candy cab variety, by chance?

[MajorPainTheCactus]

Ok yes I think we’re in luck as I think I’ve done that already (I think) - the user just needs to up the display resolution to 8K and it will use that mask (for 4K screens it has the effect of halving the effective resolution). I’m going to add 300TVL option for this though as it’s a bit more obvious/explicit.

[GPDP1]

Currently I’m doing an optimisation pass as the colour grading stuff has made things SLOW (still faster than most shaders but not as fast as it was).

And how! My PC running Lakka using an Intel HD 630 used to be able to run this shader at full speed, but after the recent updates, it is now insanely slow. We’re talking one frame a second, or less!

Now, I can’t really use this shader as intended because the HD 630 only supports 4K at 30 Hz and doesn’t support HDR (even when it ran at full speed, it looked wrong due to lack of HDR support, so there was no point in using it), so maybe take this with a grain of salt, but still. It can handle guest-advanced-fastest just fine, but this shader completely obliterates it now. Even running it at 1080p does no good. On the other hand, my Windows laptop’s Quadro K1100M handles it just fine (albeit at 1080p, haven’t tried it at 4K), but I’m not really surprised by this.

[hunterk]

Hmm, if it’s going that slow, there’s probably something wrong beyond just needing some optimization. GPU drivers can be weird sometimes, freaking out on a specific function or whatever, and it sounds like there might be something like that going on here.

EDIT: I just loaded the shader for the first time, now that SDR is on there and it looks great, obviously, but much too dark (and the res is much too low) on my ancient Haswell 720p laptop lol.

However, I had to change all of the ‘include’ paths to use fwd-slash instead of the Windows-style backslash to get the shader paths to resolve. Just FYI

[GPDP1]

Yeah, I’m thinking driver issue as well. No way should it be running THIS slow. I updated to the latest Lakka version which incorporated Mesa updates, and it made no difference. Something weird is definitely going on.

For what it’s worth, the PVM 20L4 preset using the 1000 TVL mask looks damn good at 1080p on my monitor (although really, it’s more like 500 TVL at that resolution). A bit dark, but very freaking accurate regardless.

[DariusG]

My laptop with hd630 and GTX 1060 when running windows, hd630 runs all shaders much faster (like able to handle guest-advanced-fast at least), but when running Linux mint it runs much slower, Linux mint reports it as hd630(power saving mode). So it could be that driver switched the card to low speeds to save battery. Didn’t find any option to change speed as it runs the default (open source?) driver. Of course if I switch Linux to GTX 1060 with Nvidia drivers, everything runs perfect.

[BendBombBoom]

After becoming the Elden Lord I’ve had time to try out the new improvements to the shader. The SDR mode gives a much more saturation on my qn90a but still has a dullness to the image. I wonder if it’s a Samsung issue and how their local dimming works.

[MajorPainTheCactus]

No need to worry it’s back faster than guest fastest now - it’ll hopefully close in on crt-fast or whatever its called. I’ve also made a change to RetroArch itself to skip the copy at the end of frame when using HDR. Bear with me today as I’ve got a few more things to do but all is in hand on the optimisation front.

[MajorPainTheCactus]

Ah good to know I’ll change that now! Yes also to the driver thing. The shader is currently a smidgen faster than guest venom stock and about three times faster than crt-royale-kuzomi - the optimised version is a good deal faster than that which I’ll submit shortly.

[MajorPainTheCactus]

I’ve just done my first pass on performance as I noticed the Sony Megatron had slowed right down after adding colour grading as pretty much expected. I measured it at 0.4ms on a 3080Ti obviously this is not a problem in any case but I’m really interested in getting this working at 4K on a Pi4 at 60fps in SDR mode which I will come to.

All are profiled in the same scene of Snes9X (Current): Legend of Zelda in the opening room using Nvidia NSight 2021.3.1 on a 3080Ti at 4K.

So here’s the list of shaders/presets I’ve profiled (just out of curiosity) in ascending order of speed in SDR mode (The Sony Megatron is by far the fastest in HDR as it doesn’t have the additional overhead of the HDR shader/copy):

crt/crt-geom-deluxe.slangp: 2.36ms

presets/crt-royale-kurozumi.slangp: 1.05ms

crt/crt-royale.slangp: 0.99ms

crt-guest-advanced-2022-01-07-release1/crt-guest-advanced.slangp: 0.87ms

crt/crt-geom.slangp: 0.68ms

presets/crt-guest-dr-venom-stock.slangp: 0.63ms

crt/crt-lottes-fast.slangp: 0.37ms

crt-guest-advanced-2022-01-07-release1/crt-guest-advanced-fastest.slangp: 0.33ms

crt-easymode.slangp: 0.27ms

hdr/crt-sony-megatron-sony-pvm-2730.slangp: 0.19ms

crt/zfast-crt-hdmask.slangp: 0.10ms

Let me know any more you want me to profile!

[MajorPainTheCactus]

Its really strange as that display should be a match made in heaven for this shader. It does sound something TV side if SDR mode isn’t working that well - you’ve got brightness turned all the way up btw?