hw.snd.vpc_0db crazy default?
aragon at phat.za.net
Sun Dec 6 09:44:06 UTC 2009
For a while I've been finding that more and more of my music has been
sounding really distorted at high volume levels. I initially shrugged
it off to bad mastering, but after playing some music that I know well
today, I finally got to the bottom of it.
In my hunt for the source I noticed that if I kept the volume level at
or below 50% in my player app, everything would sound fine. Anything
above that and distortion just gets progressively bad. So I started
digging into FreeBSD 8.0's new sound system and noticed the
hw.snd.vpc_0db tunable that defaults to 45.
Basically I'm gathering that at that default, when a sound app has its
volume level at 45%, the sound system performs zero gain or attenuation
to the app's output. Volume levels above that will cause source
material with a high recording level (just about all music these days)
to clip due to the sound system now applying soft gain. This strikes me
as crazy. Surely everyone who plays music on FreeBSD 8.0 must be
experiencing distortion above 45% volume levels because of this default?
Why does this default to 45% and not 100%, or maybe 95%?
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