Toying with ffmpeg and hardware acceleration is intriguing. Why? because of experimenting, now we know that we can maximize the hardware we had.
By default, these chromium-based browser will not try to output more than stereo channel to your sound system. I've tested them myself with Edge. Turns out, you need to enable them to do it.
To enjoy Dolby Digital 5.1 Surround Sound via HDMI without the need of passthrough, we need some software to encode PCM/regular codec audio to Dolby Digital. In this tutorial, we will figure out what you need to install them.