Bug Report Full Screen Display Capture - Black with 4K/UHD Only

[Bob Denny]

Here is a video I made of the problem I have. Much easier than to try to explain it only to have "quick-look" readers respond to tell me to switch OBS to my Intel video adapter etc. I do not have a laptop. I do not have two video adapters. This PC has only the nVIdia 1070 and it's running 4K on my Samsung 4K monitor (see image below for my system specs). This is using Display Capture, which I need because I want to include a magnified overlay of part of the main display. The attached Black Display.log is from the initial run where the OBS display goes black, the Normal After Restart log is from when I restart it in the video. So out further ado:

Note it displays fine (and records 4K/60fps fine) until I open X-Plane into full-screen (presumably direct to the adapter) output. Oddly I have been able to get this to work intermittently. Yesterday I was able to record a 20 minute video with XP in full screen. The next one, no luck. I tried lots of things, changes to the nVIdia Program 3D settings for OBS, I even rolled back to 21.1.2 since lots of people are complaining of this after upgrading to the latest version. No luck with 2.1.12 either. Same problem.

I really love OBS and find it incredible. I am a donating user too. I use it regularly to stream video programs to my astronomy software customers.

 

[Osiris]

Fullscreen games cannot be captured with display capture. And you also seem to have multiple display captures, you can only use a single display capture source per monitor.

 

[Bob Denny]

Interesting. I was able to create a 20 minute video recording from my 4K UHD full screen using the scene with two Display Capture sources: one full screen, the other with a Crop into a rectangle that I stretched to 3X size as a magnified view. It worked beautifully. I even set up a keyboard shortcut to show/hide the second Display Capture magnified view. Then I discovered that my audio mixer had a meltdown and distorted the hell out of my audio. When I went back an hour later to repeat my success I could intermittently see the screen in OBS, but then on clicking into the big monitor it would disappear. During the video I was clicking into the big screen for 20 minutes.

Anyway, it is very close to working. In fact it will work under the right conditions (which I apparently have not been able to re-create). The recipe is a secret like Coca Cola ha ha.

I tried Game Capture and Window capture. Neither will let you have multiple sources coming from the same video. Dang, the magnified view was the whole reason I wanted to use OBS. I ended up using nVidia capture. Maybe when I have copious time (haha) I will grab the sources and see where it's getting jacked up. It's really close!!

 

[Bob Denny]

Post script: I just took a quick scan of the source code on GitHub. You may be mistaken with the absolute statement that you cannot do multiple captures from the same monitor. Look at this:

 

[Bob Denny]

So, I reproduced the test on a different system here:

Not a laptop, only the nVidia adapter. nothing more. Display Capture from the same simulator running full screen, and a second Display Capture from the same adapter/monitor working fine. I can click back and forth between the two. I show the sources properties to prove this is what I'm saying.

I'd really like to solve this one. When I get additional time I will start doing different things on the other system to see if I can narrow down what's happening

 

[Bob Denny]

Darn it... I tried changing the sim to 1080p (half resolution) as it is working on my office system with OBS (see above). Still no luck. I tried turning VSync on and off. No luck. This is sooooo close. I can start OBS on the smaller (1080p) screen and see the full UHD screen in OBS . I can make adjustments, add and move crop filters, etc. I can make recordings. However, the second I click in the simulator itself, on the big screen, poof, OBS goes to black screen, and will not recover without restarting it. See the video below.

Is there something I can turn on - a setting maybe - that would provide additional logging?

I have attached a video and the OBS log where OBS starts up showing the simulator then I click in the simulator on the big screen and OBS goes black. I can't see any evidence of this in the log. If you look at the time stamps, there are some errors listed during startup, but they don't seem to be relevant because it comes up showing the simulator fine at 11:26:22.396. Then I click in the sim, the OBS display goes black, and nothing in the log. Then at 11:31:15.093 I shut OBS down. No evidence of any errors.

 

[Osiris]

Post script: I just took a quick scan of the source code on GitHub. You may be mistaken with the absolute statement that you cannot do multiple captures from the same monitor. Look at this:

View attachment 39287

Yeah, but from my experience that doesn't always work.
This is also something I can't reproduce, if OBS is active i see X-plane and if X-plane is active I still see X-plane, though it goes black momentarily, it is possible that when it goes black momentarily one of your other display captures picks it up.

It might be better to use game capture to capture X-Plane, this works better.

 

[Bob Denny]

Yeah, but from my experience that doesn't always work.

Let's get it fixed ha ha!!

I have also tried Game Capture. I only have one Display Capture in the active Scene (see the log, it is the Basic scene that I am using in the above video). I am indeed seeing the main X-Plane screen go black for an instant. The OBS display capture goes black forever, requiring an X-Plane restart to even capture X-Plane Windowed!! I am praying for someone who can show me a trick to identify the issue. I work with Visual Studio every day, but I am really busy with ral work... one day I may bring down the sources and see what I can see, or at least add logging to help me spot what's getting hosed.

 

[Osiris]

Did you check your other scenes that have a display capture source that is set to capture the screen with X-Plane? To see if one of those picked up the image?

 

[Bob Denny]

No, I will do this in a test today and report back. Thanks for working with me on this! I really appreciate it. If I can get this going it will be good for others here.

 

[Bob Denny]

BOOYAH! I stripped out everything, removing the webcam source and having one display capture on the UHD 4K display. Here is what I did to get it to start functioning:

• Display Capture: 3840 x 2160 + Sampling filter down to 1920x1080, Lanczos, Undistort center. Thus the source is 1920x1080 at this point, and the rest of the chain runs at this resolution and FPS.
• Settings: Video - Canvas (base) 1920x1080, Output (scaled) 1920x1080, Bilinear (but no scaling right?), 60 FPS
• Settings: Output Streaming - NVEnc H264, no scaling of video
• Settings: Output Recording - Custom/FFMPeg, MP4, no scaling of video. Produces perfect 1920x1080/60FPS MP4.

Now, when I click in the full screen X-Plane on the UHD monitor, it flashes as before, and OBS screen capture on the other (HD) monitor goes black... for 2-3 seconds... then it comes back and continues to capture 100%.

@Osiris thank you for sticking with me and giving me a direction to head in. I plan to add a second display capture cropped and scaled down to 1920x1080 resolution to give me a magnified view of a small part of the screen (which is why I want OBS instead of the nVIdia native overlay capture). I'll let you know how it goes. I NEED TO PLAY AROUND MORE. I DO NOT WANT TO CREATE AN OLD WIVES' TALE HERE! DO NOT ASSUME THAT OBS CANNOT HANDLE UHD!

 

[Osiris]

If you want to use a display capture multiple times, when adding them you use the Add Existing option, they can be cropped individually.

 

[Bob Denny]

@Osiris that's brilliant! Thank you again :-) I will report back later today. I need to get to work now.

 

[Bob Denny]

Here's the final analysis on this:

• My primary display is 4K/UHD (3840x2160) and 60Hz. If I create a Display Capture and include a scaling filter to (immediately) reduce its resolution to 1080p HD (1920x1080), then I can do anything I want with it. It always works (with a 2-4 second delay after clicking within the big display).
• All of the other settings in OBS (streaming, recording, video) are set to 1920x1080 / 60fps.
• Recording at 1080p/60FPS works great, and no impact on FPS even with the 2:1 downsample scaling. Must use ffmpeg if you plan to edit in (e.g.) Sony Vegas though, or you get no audio when you bring it into Vegas ?!?!?!?!
• Streaming is fine as well.
• I tried @Osiris' suggestion above, but adding the crop caused both instances to be cropped, and also changing the name of the "added existing" change it everywhere. I ended up with only a cropped source.
• I did add a second Display Capture, added it's own scaling filter for 1920x1080, then added the crop filter in addition. This worked great. The magnified overlay is working as it should. Thus multiple Display Captures from the same display adapter is definitely supported.

Bottom line: Piping 4K/UHD into OBS can cause problems. Downsample to 1080P HD and all will be well.

 

[koala]

I tried @Osiris' suggestion above, but adding the crop caused both instances to be cropped, and also changing the name of the "added existing" change it everywhere. I ended up with only a cropped source.

Don't crop by adding the crop filter. Instead, hold down the ALT key and drag the border markers of the source in the preview with the mouse to crop. If you hold ALT, you crop. If you don't hold ALT, you resize. This kind of crop is not duplicated with "Add existing".

 

[Bob Denny]

Oh... I will try this. I want a magnified part of the screen, so I will try ALT-border followed by NotALT-border to make it bigger. I was unaware of the ALT trick thanks. In any case the actual second Display Capture+Crop+Expand works great. I'm real;ly busy this week, I'll try to post the results this weekend as a video. Thank you again for your help!!