[Steam][SDL][OpenAL] Stuttering sound in many Linux games

Hello folks.
On my Linux system (up-to-date Arch Linux) I was having trouble with several open-al based games, namely Psyschonauts, Super Hexagon and FTL/Faster Than Light. All games were purchased via Steam. The problem was, that the games' sounds came out somehow garbled - stuttering to be more precise. All I could do was restarting the game once or twice and hope that it would finally do as intended. As there are several components involved and common to the stuttering sound (SDL, OpenAL, Steam, Pulse Audio, Linux), it was not easy for me to put the problem into words google could understand.

After doing a lot of research with no results of which none of them solved my problems, I finally stumbled about a small, german  forum post, that seemed somehow to be connected to this issue. It also mentioned high cpu load when these problems occur, which I could confirm espacially while playing FTL. The post was suggesting that it might help to go into Mixer/ Pavu Control, take the particular audio stream of the game (for steam games it is usually a steam-connected strem), and turn it down a little - from 100% to let's say 90%. And voilà: After following this advice I seem to have no troubles left with those games.
If you don't have a program calles "Pavu control" or Pulse audio Mixer yet, it is almost certain that you will find it in your distribution's repository.
And that's it!

But wait - what happened? As the mentioned post suggests, it is a problem of the sound overmodulating. I guess, there is an (artificial) limit set to the physical outgoing sound volume, that causes sounds which are too loud to be filtered. Since this is probably an expensive operation, intercepting the audio stream, filter it and continue to play it again, this will presumably cause the high cpu usage noticed before. I don't know why, but openAL seems to cause a lot of those too-high sounds to be generated (at least the version used by steam).
Now, by setting the limit of the virtual stream lower than before, this problem gets solved.

Happy playing!

Linux dual monitor: Don't stretch fullscreen over all monitors in SDL games (psychonauts, ftl, superhexagon)

[EDIT] Some time after I wrote this, I also found this article:
http://www.maketecheasier.com/run-fullscreen-games-in-linux-with-dual-monitors/
which is a lot nicer written.

Hello everybody!

I'm using two monitors on my Linux machine: The 13" 1366x768px inbuilt one of my laptop and my 24" full hd monitor. I don't need to say, that those do not really match to display one application over both of them. Unfortunately though, many games based on the well known sdl library try to do exactly this: When in fullscreen, they only offer me resolutions like "3286x1080" after the notebook's resolution (nothing in between). When opening in windowed mode, they calculate the middle of the screen by taking both screens into consideration, thus opening between them.
All I want to do, though, is having fullscreen games opening with full hd resolution on my external monitor, and windowed games in the middle of just this monitor.

I was quite happy lately, when I discovered that wine/crossover will open all windows on the external monitor if I tell xrandr, that it is my "--primary" screen, using "xrandr --output HDMI-0 --primary". This doesn't work for native, sdl-based games of course, although it kind of fits in here, so I thought to mention it.

So, today I got my bluetooth controller and I really wanted to play psychonauts with it. It, too, featured the said issue, and this time I just didn't want to give up. After some heavy googling, I finally came up with the SDL_VIDEO_FULLSCREEN_HEAD variable mentioned HERE (archwiki ftw!), and -thank god- it worked as expected. So for you it is:

$: SDL_VIDEO_FULLSCREEN_HEAD=0 ~/.steam/root/SteamApps/common/Psychonauts/Psychonauts

I hope this helps someone out there. I wish happy gaming.
Sincerely

suluke

Related: 
A topic on a mailing list also discussing a similar solution can be found here: http://icculus.org/pipermail/psychonauts/2012-June/000000.html