Weird volume behaviour on 10.0-BETA4

[Randy Pratt]

On Sat, 07 Dec 2013 11:11:59 +0100
Julian Stecklina <jsteckli at os.inf.tu-dresden.de> wrote:

> 
> 
> Shane Ambler <FreeBSD at ShaneWare.Biz> wrote:
> >I have seen the same thing on 9.2 with vlc. Previously the volume
> >stayed at a stable level.
> >
> >But for a while now it always starts a new file at 45% volume.
> 
> Are you using USB audio?

I noticed this some time back particularly when playing multiple
audio files at the same time.  I have a few notes on it.  I'm not sure
if all of it is still relevant but it may help:
=============================================================
Restoring Sound to old behavior

The default behavior is to restore audio volume to a certain level
each time an application using sound is started.

Check default settings using sysctl -a. These are the particular
settings controlling VPC (Volume Per Channel)

     hw.snd.vpc_reset: 0
     hw.snd.vpc_autoreset: 1

See http://people.freebsd.org/~ariff/SOUND_4.TXT.html for more info
where I thought the following should restore the persistent volume
level behavior:

     # mv /var/db/mixer0-state /var/db/mixer0-state.disabled 
     # sysctl hw.snd.vpc_reset=1 
     # sysctl hw.snd.vpc_autoreset=0

Since I could not change at the command line:

     # sysctl hw.snd.vpc_reset=1
     hw.snd.vpc_reset: 0 -> 0

I added it to /etc/sysctl.conf:

     #Added to prevent mixer from resetting sound levels to default
     hw.snd.vpc_autoreset=0

Sound seems persistent across playing multiple files by changing "hw.snd.vpc_autoreset"
=============================================================

If something is different from above you might reply so that it
would help others.

Randy