[PM 25.8.1 x64] HTML5 sounds play through left speaker only

[freefrog]

It seems there's a problem with sound processing when playing HTML5 videos in Pale Moon. Some HTML5 videos only play mono sound through the left speaker. Apparently this problem happens on very specific hardware configurations only.

Here are two videos from the same site that produce different results.
Sound is working as expected: https://www.youtube.com/watch?v=49En0xjh0Xg
Left speaker only: https://www.youtube.com/watch?v=42hBaXqP50g

Tested on:
- Win7 x64 SP1
- Pale Moon 25.8.1 x64 (all extensions and plugins were disabled for this test)
- Razer Megalodon (USB headset), Realtek ALC889 - both produce the same result

Mozilla fixed this longstanding issue in FF40 release: https://bugzilla.mozilla.org/show_bug.cgi?id=979705

[Moonchild]

Thanks for the report. WASAPI support is actually relatively new for us so there's still a few glitches.
It's easy to fix though, by the looks of it. Expect this to be fixed in the v26 milestone.

(as an aside, the mono sample does play over both speakers for my setup in the YT HTML5 player in Pale Moon 25.8.1)

[freefrog]

GitHub commit: Copy mono channel to L+R channels for WASAPI channel upmixing

Thanks for the quick response. Since my hardware configuration is known to have this problem, I'll check these videos again after PM 26 release and post here if issues arise.

Happy holidays!