FMV audio desyncs

[Skirmisher]

Not totally sure where to put this issue; this repo seemed as good as any, since it has to do with running the game in Proton on Linux.

When running the FAF-patched ForgedAlliance.exe independently from the FAF client, I noticed that during the opening movies, the video starts falling behind the audio, with the delay adding up to a second or more if the movie played for long enough. Presumably this would affect any videos with audio in the game, such as campaign dialogue portraits, but I haven't tested further yet.

Notably, this doesn't happen with vanilla Forged Alliance from Steam (using the same Proton prefix as FAF); e.g. the opening movies have perfect A/V sync throughout.

Tested on a Steam Deck, as well as a laptop with an Intel Core i7-8550U running Fedora 39 (where the effect was substantially worse—the video was at least a second behind the audio after ~20 seconds of movie runtime). Both machines used Proton 9.0-4.