For your own good we enforced real-time protection…

Ostatnio spedzilem dosc duzo czasu na sprawdzaniu problemu z nieoczekiwanie slaba wydajnoscia w… Oh wait I am writing in English here. So, recently I spent rather a lot of time checking a problem with unexpectedly poor performance in a legacy DirectShow real-time video encoding pipeline based on NVIDIA GPU hardware encoding.

There was also a pre-history in this story. A colleague engineer in a contracted organization complained on a similar symptom and it took me not too much time to see that some third party antivirus is showing unexpected load numbers along with video recording activity. It appeared that it was not so easy to disable the antivirus because it was managed by his company on the corporate development system, so I just left him with suggestion to find ways to kill the offender.

However then later a similar thing happened on my own system as well. Even though it was a good reason to fine tune other aspects of the pipeline it came to my attention that freezing parts are happening in disk access to produced file in MP4 Multiplexer filter here.

The whole situation is ridiculous. Geraint designed these filter back in 2009 and then those would work nicely even ten years earlier if they existed earlier. Now with all the performance progress in hardware the same code exhibits extremely weird performance behavior because… of this thing:

Real-time protection of Windows defender interferes with recording so bad that it holds the entire upstream pipeline and forces frame drops in already a few second after start. This thing is also known to automatically re-enable itself if you turn it off so ironically even when I turn the switch on the image above off, after just a few minutes of rock solid operation it re-enabled the protection and the recording defect immediately returned back (okay, maybe it popped a notification about disabled protection and I accidentally clicked).

What’s wrong with this thing at all? Is it really that important to routinely check MP4 files being written with an impact so high that you can no longer use the hardware to do that original most important operation.

Knowing this, of course, it is important to restrain the scoundrel:

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