OBS is crashing when I choose Blackmagic WDM Capture to stream our 6k Pro.

ChaplainTIG

ChaplainTIG

New Member
OBS is crashing when I choose Blackmagic WDM Capture to stream our 6k Pro. For some reason, the Decklink Video Capture option isn't working. So looks like the Blackmagic WDM Capture is the only option that shows camera output, but it brings up a crash notice immediately. After looking at the crash log, I updated to the most current version of Blackmagic Desktop video v12.4.2, but the problem repeats. Also, we are on the most current version of OBS v29.1.2.

Crash log
Unhandled exception: c0000005
Date/Time: 2023-06-07, 15:56:53
Fault address: 1B41D2829FA (c:\program files\blackmagic design\blackmagic desktop video\decklink64.dll)
libobs version: 29.1.2 (64-bit)
Windows version: 10.0 build 22621 (release: 22H2; revision: 1702; 64-bit)
CPU: AMD Ryzen 9 3950X 16-Core Processor

I greatly appreciate any solution you can think of :)
 
PaiSand

PaiSand

Active Member
According to the cutted crash report snippet you posted the crash happens in the Blackmagic product and causes OBS to crash.
You should contact them too.

Make sure it supports OBS latest versions.
 
ChaplainTIG

ChaplainTIG

New Member
PaiSand said:
According to the cutted crash report snippet you posted the crash happens in the Blackmagic product and causes OBS to crash.
You should contact them too.

Make sure it supports OBS latest versions.
Click to expand...
Excellent point. Thank you!
✅ Just emailed them too.
 
ChaplainTIG

ChaplainTIG

New Member
Not working yet, but update after working with Blackmagic dev team.

Here's their latest reply after I was able to successfully stream the camera footage through the Blackmagic SDK.

I appreciate the video! That shows us quite a lot of information, thanks!
(He's referencing a video I made to demonstrate the issue - video walkthrough: https://photos.app.goo.gl/9zPoQ9TD3WXkicxq6)

The 'Blackmagic Device' on OBS should be working, as this uses our SDK to control the card. The 'Video Capture Device' is using Windows to get generic video input devices connected to the system. Both should work.



For reference, there are two ways we facilitate interaction with the cards.

  1. Using our SDK/API to communicate directly to the card - providing direct driver control through code
  2. Through the operating system's multimedia framework. For Windows, this is using DirectShow filters.
The DeckLinkAPI is the preferred way to work with the card. However, for applications that haven't implemented our API, using the multimedia framework allows the DeckLink card to be listed as a generic "Video Capture Device" in the operating system.



The OBS team have implemented our API directly into their Software, which is why there's the "Blackmagic Device" option. This should work. I've tested OBS 29.1.2 with Desktop Video 12.4.2 and I see the video stream without issue when using the 'Blackmagic Device option'. It is a little concerning that this isn't working for you.



A couple of further things to try:

  1. In the Win folder of the SDK is a folder called 'samples'. Can you please check the CapturePreview sample application from the 'bin' folder and let me know if you can see a picture using this?
  2. Does capture work with MediaExpress? This will have been installed with the Desktop Video software.
  3. Finally, have you tested it directly from the camera using the HDMI input on the card (Bypassing the HDMI->SDI converter)?
I will set up a test today to capture 8-bit video at 1080p30 on the DeckLink Mini Recorder 4K card. I will let you know the results of the test once I have some data to share with you.
 
ChaplainTIG

ChaplainTIG

New Member
Additional things I've tried...

Here's what I've done...

I uninstalled OBS and Desktop video, restarted, downloaded and reinstalled them both, restarted and the problem remained.

I moved the decklink card to another PCI slot and the problem remained.

The problem remains that:
  1. With DecklinkCapture exe from the SDK, the video stream shows on both Decklink Video Capture and Blackmagic WDM Capture options perfectly in YUV 8-bit and YUV 10-bit.
  2. In OBS, the Decklink Video Capture option never shows any video output,
  3. and the Blackmagic WDM Capture option shows the video stream, but immediately pops up a crash message.
  4. 1686780942029.png
    The stream shows up perfectly from Media Express.
  5. The problem persists whether the camera is connected to Decklink through HDMI or SDI.
This one's melting my brain. hahaha
 
ChaplainTIG

ChaplainTIG

New Member
BlackMagic was kind enough to send me a new card and the problem remains.
They also cannot duplicate the issue with their own system, so it looks to be something specific to my setup, but it's not the capture card.
 
ChaplainTIG

ChaplainTIG

New Member
Thank you @PaiSand ... also, love your tagline! Appreciate the PDS reference and excellent advice.

FIXED - I ruled out hardware issue thanks to Blackmagic kindly sending me a replacement board. Out of frustration, I uninstalled OBS and completely removed all settings, and then reinstalled. Everything worked flawlessly after that. I had reinstalled twice before, but had not removed all settings, so there must have been some past setting or plugin that was gumming up the works.

Anyway, MASSIVE thank you to all of you who have helped me resolve this issue. Many, MANY thanks to you all!
 
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