Flickering output: Desktop Video 10.9+ and Black Burst sync

Hello!

A couple of weeks ago I experienced an issue with flickering output from Decklink cards_ when I tested a new hardware using CasparCG Server v2.2.0 Beta. After a bunch of tests and some chats with @Julusian and @ronag I finally found the issue and why the output flickered and wanted to share that information with you.

I can only confirm this when using video-mode 1080i5000 in CasparCG Server. I have also tested this by using CasparCG Server 2.0.7 Stable with same flickering results. All tests has been done using two completely different machines (see table below) to verify this issue.

The flickering seems to occur when using Black Burst-sync with Desktop Video v10.9+ and stops flickering if you use Tri-level-sync instead. However, using Desktop Video v10.8.x with Black Burst works well. Once again, I can only confirm this when using 1080i5000 and if somebody has more additional information please feel free.

Combinations: Sync-type and Desktop Video Versions

	Flickering: Black Burst	Flickering: Tri-level	Tested on
Desktop Video v10.11	Yes	No	Setup 1, Setup 2
Desktop Video v10.10	Yes	No	Setup 1, Setup 2
Desktop Video v10.9.x	Yes	No	Setup 1, Setup 2
Desktop Video v10.8.x	No	Unconfirmed	Setup 1, Setup 2

Setups

	Setup 1	Setup 2
Machine	HP Workstation Z4	HP Workstation Z440
CPU	Xeon W2135 3.7GHz 6C	Xeon E5-1650V4 3.6GHz 6C
Memory	32GB	16GB
Harddrive	HP Z Turbo Drive 256GB M.2 SSD	Samsung 850 Pro 256GB SSD
Graphics	Quadro P4000 8GB	Quadro M4000 8GB
Decklink	Quad2 and Duo2	Quad2 and Duo2
OS	Windows 10 LTSB	Windows 7 Pro

I'm experiencing something similar... I'm off on holiday tomorrow, however will return with some more information / behaviour to see if there is a fix. (I also came across another post where people have experienced similar and recommended downgrading driver / different sync / different power source)

It turned out to be a PCIe lanes thing for me... changed the slot I had my BMD card plugged into and it started working!