Again on this, I just reverted the aspect to force it to be 4:3 for VGA* presets, since VGA monitors were 4:3.
Also, I just realized that following the core aspect would break almost all overlays that needs to blend with the monitor frame when core does not report 4:3.
So the behaviour of the preset “-7” is to use the core aspect when no BG/FG image is used, and another preset, “-8” has been added to always force core aspect:
Just an opinion: I think leaving the default aspect at 0 is the safest and most compatible option with our presets and cores, and -7 -8 should just be optional, not the default.
Yes, Retroarch has few issues, that even affects CRT, like per example having notifications on, blurs the CRT image, and looks less sharp. I think in Retroarch there are invisible layers that affects the whole image in general, also taking simple simple preset saving off, affects CRT also. It took me quite a while to figure out that, and I could realise it was there thanks to my CRT. That’s why also affects shader settings. No wonder this kind of issues happens as well. Also another thing I found is that using different video drivers affects slightly the image too. GL and D3D11 looks best on a CRT. Just to let you know.
Ok, I tried with other shaders/presets from MegaBezel and Uborder and it only happens to me with Koko.
What I did was rotate the image by -2.00
Since you asked “why sometimes”, i thought it appears as random to you, hence i suggested the cause that could appear random to you 
I can’t really answer anything else as long as you are not more specific, as nothing else crosses my mind…
If you found the cause and the solution, please share!
edit:
Else, if you give me 2 cases that appear the same to you, but reacts differently, olease post the stuff (game/png) so that I can scratch my head as well.
Yes, I’ve been investigating and what these vertical games have in common, and what it could be is that these games have 90° rotation, the background is upside down.
For example the games:
I found this information on the site http://adb.arcadeitalia.net/dettaglio_mame.php?game_name=xevious
Unlike games that load the background correctly, they have 270° rotation For example the games:
I hope this information is useful.
It will probably be, thank you!
Will investigate in the next days
On the other side, trusting core reported aspect fixes multimonitor games like punchout or darius… choices…
Those are a few rare games to my knowledge. The user can just give them separate overrides.
I just pushed a commit to handle all rotation states for what concerns background and foreground images, so it should be sufficient to just set the rotation to 0.0 (auto).
Other options for manual rotation are in place and untouched to not break existing presets handling the mess manually.
I tried 0,90 and 270, but failed to find something that needs 180 degrees, but it should work.
Can you confirm?
I get an error when I try to load the shaders, for example koko-aio-ng.slangp
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\colortools_and_ntsc_pass.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #0.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\fxaa.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #1.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\shift_and_bleed.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #2.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\in_glow_x.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #3.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\in_glow_y.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #4.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\halo_pre_gamma.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #5.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\halo.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #6.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\avglum_pass.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #7.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\reflection_blur_pre.slang".
[INFO] [slang]: Using render target format R8G8B8A8_UNORM for pass output #8.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\reflection_blur.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #9.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\bloom_pass_1.slang".
[INFO] [slang]: Using render target format R8G8B8A8_UNORM for pass output #10.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\bloom_pass_2.slang".
[INFO] [slang]: Using render target format R8G8B8A8_UNORM for pass output #11.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\bloom_pass_3.slang".
[INFO] [slang]: Using render target format R8G8B8A8_UNORM for pass output #12.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\bloom_pass_4.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #13.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\ambi_temporal_pass.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #14.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\helper_pass.slang".
[INFO] [slang]: Using render target format R16G16B16A16_SFLOAT for pass output #15.
[INFO] [slang]: Compiling shader: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\shaders-ng\final_pass.slang".
[INFO] [slang]: Using render target format R8G8B8A8_UNORM for pass output #16.
[INFO] [Vulkan filter chain]: Creating framebuffer 512x512 (max 4294967295 level(s)).
[ERROR] [slang]: Unknown semantic found.
[ERROR] [slang]: Failed to reflect SPIR-V. Resource usage is inconsistent with expectations.
[ERROR] [Vulkan]: Failed to create preset: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\koko-aio-ng.slangp".
[ERROR] [Vulkan]: Failed to create filter chain: "D:\Games\RetroArch\shaders\shaders_slang\bezel\koko-aio-test\koko-aio-ng.slangp". Falling back to stock.
[INFO] [Config]: Saved new config to "D:\Games\RetroArch\retroarch.cfg".v1.19.1
The latest version has problems with the wildcard $CORE$
Ok, there’s something unhandled then.
What was your “previous” koko-aio version, before the failing update today?
prior to this last commit 29/01
I made a backup of that version.
I guess you’re right after all, too bad tho. Done.
It should be ok now…
Now it works fine. Thank you so much
