That was from one PC, out HDMI to splitter, one to a TV with output to headphones and other to Decklink. Never heard any scratching in the headphones from the TV's copy of the audio stream. But in testing and watching audio levels in OBS, I can see the audio peaking when it does that "glitching"
I've also recording video for an HOUR using Media Express to SSD and had it glitch several times (no HDMI splitter). I've also "passed" through the HDMI output on Decklink, but haven't had a chance to listen for and glitchy audio when capturing as I normally am not listening to that audio (but it is something to do, but doesn't change the fact that the card glitches when it should not happen).
Known facts: It will glitch (capture bad audio from HDMI source) given long enough time (30 minutes is usually enough to glitch once if not twice).
As I don't have SDI hardware I haven't been able to test SDI capture -- I hate to purchase SDI converter.. If it work with SDI input, then I should not have gotten the Decklink Studio 4K (which I got because it has HDMI input). **IF** should have gotten SDI input/output only and SDI converters, then it's way to late to exchange and get that. I already spent a sizable amount of money on this card.
--Doug (dx9s)