[TF2] [Linux] SDL_AUDIODRIVER=alsa results in black screen after recent 3.0 runtime update

[Poto-Feu]

Setting the environment variable SDL_AUDIODRIVER to alsa in TF2 launch options results in a black screen and no audio after one of the recent Steam Runtime 3.0 (Sniper) updates.
Removing the environment variable works. However, changing the SDL audio driver to ALSA fixes an issue related to the game sound occasionally no longer playing after alt-tabbing or after opening the Steam overlay.
This is clearly a regression as setting the environment variable worked before this update.

[smcv]

@slouken, does this seem familiar from a SDL point of view?

[smcv]

one of the recent Steam Runtime 3.0 (Sniper) updates

What is in steamapps/common/SteamLinuxRuntime_sniper/VERSIONS.txt in a non-working version?

Since last week, I would expect depot 3.0.20260331.220801 for the public beta, or depot 3.0.20260316.216289 for the stable release.

The stable release contains updates to SDL 3 (3.4.0 → 3.4.2) and SDL 2 ("classic" SDL → sdl2-compat), either of which could be relevant here. The next public beta release is likely to contain further SDL updates (3.4.2 → 3.4.4 and sdl2-compat 2.32.64 → 2.32.66) which might fix some relevant regression.

One thing you could try is setting the Launch Options to STEAM_COMPAT_RUNTIME_SDL2=classic SDL_AUDIODRIVER=alsa %command%, which reverts to the old ("classic") SDL 2.

changing the SDL audio driver to ALSA fixes an issue related to the game sound occasionally no longer playing after alt-tabbing or after opening the Steam overlay

That's a workaround, more than a fix: ideally SDL's default audio backend would work well after alt-tab or the Steam overlay.

What audio server are you using on the host system? (PulseAudio? Pipewire + pipewire-pulse? Something else?)

[Poto-Feu]

What is in steamapps/common/SteamLinuxRuntime_sniper/VERSIONS.txt in a non-working version?

depot	3.0.20260316.216289			# Overall version number
pressure-vessel	0.20260313.0			
scripts	0.20260313.0			# from steam-runtime-tools
sniper	3.0.20260316.216289	sniper	3.0.20260316.216289	# sniper_platform_3.0.20260316.216289/

One thing you could try is setting the Launch Options to STEAM_COMPAT_RUNTIME_SDL2=classic SDL_AUDIODRIVER=alsa %command%, which reverts to the old ("classic") SDL 2.

Using STEAM_COMPAT_RUNTIME_SDL2=classic fixes the issue so it seems to be related to SDL2-compat.

What audio server are you using on the host system? (PulseAudio? Pipewire + pipewire-pulse? Something else?)

pipewire 0.3.44 with pipewire-pulse (the version shipped with Slackware64-15.0) and wireplumber 0.4.7 (built from Slackbuilds).
Using the ALSA backend on other applications such as xine or Wine do not cause this issue.

[smcv]

an issue related to the game sound occasionally no longer playing after alt-tabbing or after opening the Steam overlay

Since you say you're using Pipewire, this original issue might have been libsdl-org/SDL#14916. If so, it's likely to be fixed in a future sniper beta by the update to SDL 3.4.4.

[smcv]

Still with depot 3.0.20260316.216289, If you set the Launch Options to SDL_VIDEODRIVER=x11 SDL_AUDIODRIVER=alsa %command% (do not override STEAM_COMPAT_RUNTIME_SDL2 this time), does that also work around this, or does the game still crash in that configuration?

[Poto-Feu]

After upgrading pipewire to a more recent version (from the Slackware 15 testing repository, not the stable one), it seems that this problem has disappeared. I can run TF2 with SDL_AUDIODRIVER=alsa without any other environment variable. This might have been a quirk of an older Pipewire version.