Topic on Engine talk:Source

So, my cousin wanted to have a ass-breaking surround experience with his 5.1 setup in CS:Go.
Even if using a 6 years old ALC662 I mean.. FEAR with ALchemy sounded good.

So I went to use the ordinary dsound.dll and dsound.ini even for this source game and I enabled the usual snd_legacy_surround option. However rear sounds were still everything but rear... I set 5.1 in the in-game settings too.. but still no luck.
After reading this anyhow, I realized there was something missing: the 7.1 in-game setting.

So I launched every source game I had and I realized that Valve cut this last option out between Left 4 Dead 2 (original build 4777) and Alien Swarm (build 4993).
And so I thought: why they should remove the only sound mode which requires hardware audio support to work? Well, probably they removed hw audio support altogether....

The only thing I'm wondering about is why games such as Nuclear Dawn (2011) and Garry's mod 13 (2012) still have 7.1 (thus hw sound?) supported
This could probably be explained since both of them are 3d party developers, so they must license the engine in advance and then release their games after the years long development ends (contrarily to Valve games which can ship with the latest version available at release time)

So, I hope you may test if my findings are correct

So, satsun ruled all this out. Hw sound is require only and exclusively if you have more than 6 channels. And provided you have it, it works nice in newer games.
Besides I found some nice parameter to investigate:

windows_speaker_config is connected to the in-game audio setting. 1 means headphones. 4 means 2 speakers. 3 means 4 speakers. 6 means 5.1. 7 means 7.1. Higher values just produce stereo sound. (and no, stereo and quadraphonic sound is not inverted)

snd_surround_speakers (not avaiable in Nuclear Dawn and in games before Alien Swarm) is also interesting but its purpose is widely debated

Is 7.1 surround known to actually work in any Source game that uses Miles Sound System? I read it's still just 5.1 surround with the front channels repeated onto an extra pair located farther away from the center for a "wide" 7.1 channel configuration that isn't the standard 7.1 we use nowadays and it doesn't exist after Windows XP. https://i.imgur.com/VbjDcdN.gif

So now it still just sets 5.1, but without changing the Windows speaker configuration since that was also broken/restricted after Windows XP. https://i.imgur.com/rNQcBc0.png

Another thing I've noticed is that judging by API calls, Source "supports" DirectSound3D, but apparently only uses objects/buffers for speakers/channels. https://i.imgur.com/hyhJkJ3.png

On newer builds, there's the snd_legacy_surround command, which can be set to 1 if using ALchemy/DSOAL. But it reports 1 channel and there have been reports of missing channels/incorrect mapping. But to be honest, I think it's better to keep it set to 0 since DSOAL can virtualize DirectSound (no 3D) channels and simple surround speaker output won't be messed up: https://i.imgur.com/8DpU9BS.jpeg

so anyway, I don't know if there are any benefits from using DSOAL/ALchemy with snd_legacy_surround 1 compared to 0, so here's my general rule of thumb: - In-game/main menu, execute the following command: soundinfo - If it doesn't report 6 channels, run in order: snd_legacy_surround 0 snd_surround_speakers 5 soundinfo