OSS or Open Sound System is the first sound API that was supported in Linux.
Forks of OSS are also used by the BSDs and Solaris.
It was eventually replaced by ALSA due to the main developer making some modifications proprietary,
leading Linux to switch to ALSA.
However, 4Front Technologies eventually made it open-source again.
Some were dissatisfied with ALSA and were complaining about the noticeable drop in sound quality.
This eventually led me to install OSS and stick with it.
The first time i rebooted my PC, i was able to hear the noise from my headphone.
The thing is with OSS, you can tweak the audio filter so it's a bit more "raw" or enable all the way up to remove any kind of noise.
OSS unlike ALSA actually shows you the defects of analog audio, without trying to hide it from you.
One huge issue i had with OSS is the fact that some packages like Firefox, Wine and proprietary games do not have by default OSS support.
It's either completely missing (Firefox) or not enabled in binary builds (Wine-stagting).
You can use an audio wrapper that wraps ALSA calls to OSS ones but there is a drop in quality and it doesn't work all the time.
Also, OSS is very CPU intensive with high-quality settings. vmix in particular is very slow when processing videos. (i still don't know why)
However, disabling vmix actually fixes the issue.
OSS also doesn't support audio via HDMI, which ALSA does and it has incomplete support for USB audio.
Despite the noticeable increase in audio quality, it does come at the price of performance (with vmix) and compatibility.
Compatibilities with applications is perhaps the first thing you'll run into with OSS, because most of them don't expect you to use OSS.
However, it should be noted that this is a bit different on FreeBSD where OSS is actually the default sound api
so if you like OSS, you might consider switching to FreeBSD.
To record a video with OSS, the only working way is to use both ffmpeg and ossrecord.
Note that you may have to soundoff & soundon
ffmpeg -video_size 1920x1080 -framerate 30 -f x11grab -i :0.0 -c:v ffv1 $HOME/capture.mkv &
ossrecord -s48000 -b16 -c2 -R -d/dev/oss/oss_hdaudio0/loop0 $HOME/capture.wav &
If an app use OpenAL (gzdoom), you can tell OpenAL to use OSS.
Edit /etc/openal/alsoft.conf and add this line (if it doesn't exist) :
drivers = oss
If OSS is acting funny, try to run soundoff & soundon in root. (or sudo)