madshi bug tracker

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IDProjectCategoryView StatusDate SubmittedLast Update
0000620madVRbugpublic2019-09-30 05:192019-10-01 17:38
Assigned Tomadshi 
StatusclosedResolutionno change required 
PlatformPCOSWindowsOS Version10 1908
Summary0000620: Dithering options have no effect when full screen on a 4K HDR display
DescriptionWhen you try to play a 4K HDR 10bit x265 movie on a 4K HDR compatible display as long as you are full screen, dithering options have no effect.
Steps To Reproduce1. Open a 2160p x265 file that is 10bit HDR in Media Player Classic with madVR enabled.
2. Search for a scene where you can easily spot banding (normally dark scenes like in the beginning of Creed II)
3. Check the dithering in window mode.
4. Check the dithering in full screen mode.
TagsNo tags attached.
madVR Version0.92.17
Media Player (with version info)MPC-HC 1.8.7
Splitter (with version info)LAV Splitter
Decoder (with version info)LAV Video Decoder
DecodingDXVA2 Copyback
Deinterlacingauto mode
DXVA2 Scaling Activeyes
Aero / Desktop CompositionOn
Problem occurs with modefullscreen exclusive mode
GPU ManufacturerNVidia
GPU ModelGTX 1080
GPU Driver Version436.30
Attached Filesjpg file icon Dither.jpg [^] (5,127,467 bytes) 2019-10-01 16:44

- Relationships

-  Notes
madshi (administrator)
2019-09-30 09:35

Does it help if you manually switch your "device\your display\properties" settings to 8bit instead of "auto" or 10bit?
OmbraRD (reporter)
2019-10-01 02:14

I have exclusive full screen mode enabled but even without it when i go full screen MPC reports (Ctrl+J) 10 bit mode but as soon as i switch to window mode it goes to 8 bit and the dithering works fine.
huhn (reporter)
2019-10-01 08:17

that's working as intended windows 10 supports windowed fullscreen 10 bit.

if you switch madVR to 8 bit it will not try to use 10 bit anymore.
OmbraRD (reporter)
2019-10-01 16:47

I get the same result in exclusive or windowed fullscreen. In both i get no dithering. Only in window mode (not fullscreen) because it switches to 8 bit.

I attached a photo to hopefully show better what i mean.
madshi (administrator)
2019-10-01 16:52

If you want support, it would help if you actually answered my questions... ;-)

I'm still waiting for a clear answer to the question I asked in my first post.
OmbraRD (reporter)
2019-10-01 17:08

Sorry madshi, you are totally right!

Just tested switching to 8bit and dither works correctly
madshi (administrator)
2019-10-01 17:19

That means that your display probably doesn't handle 10bit input correctly. Or alternatively it's also possible that either the OS or the Nvidia driver are screwing something up with 10bit output. In any case, don't worry about it, using 8bit output is perfectly fine.
OmbraRD (reporter)
2019-10-01 17:22

I understand. Display should support if fine. It is an LG OLED B7 but while investigating the gfx side i found this: [^]

I tried a bunch of options but it won't enable.

I guess i'll run it in forced 8bit then. Thank you!
madshi (administrator)
2019-10-01 17:25

We do not want the GPU driver to add dithering. If we need dithering, madVR will do that in higher quality. But if you output 10bit, madVR will automatically lower the amount of dithering, because 10bit needs 4 times less dither noise than 8bit. So it will *look* to you as if dithering is not working. But madVR actually will properly dither the output, in any case. But if someone (display, GPU, OS) breaks the 10bit chain, that will effectively remove madVR's dithering.

Short summary: It's not the dithering you need to worry about. It's the proper handling of 10bit. Which seems to be broken in your playback chain, for whatever reason.

In any case, don't worry about it, just use 8bit output instead. Problem solved.
OmbraRD (reporter)
2019-10-01 17:35

Alright, thanks

- Issue History
Date Modified Username Field Change
2019-09-30 05:19 OmbraRD New Issue
2019-09-30 09:35 madshi Note Added: 0002557
2019-10-01 02:14 OmbraRD Note Added: 0002560
2019-10-01 08:17 huhn Note Added: 0002561
2019-10-01 16:44 OmbraRD File Added: Dither.jpg
2019-10-01 16:47 OmbraRD Note Added: 0002562
2019-10-01 16:52 madshi Note Added: 0002563
2019-10-01 17:08 OmbraRD Note Added: 0002564
2019-10-01 17:19 madshi Note Added: 0002565
2019-10-01 17:22 OmbraRD Note Added: 0002566
2019-10-01 17:25 madshi Note Added: 0002567
2019-10-01 17:35 OmbraRD Note Added: 0002568
2019-10-01 17:38 madshi Status new => closed
2019-10-01 17:38 madshi Assigned To => madshi
2019-10-01 17:38 madshi Resolution open => no change required

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