Problem with audio apps and mixer

[Paul B. Mahol]

On 7/3/09, Alexander Best <alexbestms at math.uni-muenster.de> wrote:
> wow. thanks a bunch. this new feature of having each app use it's own volume
> setting is pretty cool. however i think i'd like to preserve the volume
> setting for each application and rather not have it reset. because i think
> this feature takes the pid of the app and preserves the volume for the pid.

Negative. Same application can open and close (different) channel(s) multiple
times causing volume to be changed. You can get some patches on freebsd forums
for mplayer and others ...

> mplayer and mpd however seem to fork a new instance after a song change or
> pausing etc. so so the volume get's reset while the app is still running.

Nope, there is no *forking*.

> i might be wrong, but i think there's a typo in this description of the
> feature i'm looking for:
>
>         hw.snd.vpc_autoreset (default=1, enabled)
>             0=disable, 1=enable
>             Notes: By default, channel volume will be reset to 0db
>                    relative after the channel is closed which means that any
>                    changes will be lost and not preserved. Setting this to
> '1'
>                    will preserve the volume at the cost of possible
> confusion
>                    for other applications trying to re-open the same
>                    device (see hw.snd.vpc_reset for possible 'panic' switch
> to
>                    fix the volumes).
>
> shouldn't it be:
>
>         hw.snd.vpc_autoreset (default=1, enabled)
>             0=disable, 1=enable
>             Notes: By default, channel volume will be reset to 0db
>                    relative after the channel is closed which means that any
>                    changes will be lost and not preserved. Setting this to
> '0'
>                    will preserve the volume at the cost of possible
> confusion
>                    for other applications trying to re-open the same
>                    device (see hw.snd.vpc_reset for possible 'panic' switch
> to
>                    fix the volumes).
>
> ????
>
> so after settings hw.snd.vpc_autoreset=0 each application uses it's own
> volume
> setting AND preserves it. just what i wanted. even better because i didn't
> know this cool new feature existed. :)

Doesn't work as expected because if you use multiple applications at same time
silenced channel may and may not become extremly noise at any time - this is
OSS and not FreeBSD fault and it is implemented as is in many if not all
multimedia applications; so you may look again in freebsd forums and use
ariff@ patch for mplayer. I don't remmember there was patch for mpd, but you
can always ask politely.

> thanks again for the hint.
>
> cheers.
> alex
>
> Paul B. Mahol schrieb am 2009-07-03:
>> On 7/3/09, Alexander Best <alexbestms at math.uni-muenster.de> wrote:
>> > hi there,
>
>> > i've never had a problem to adjust the volume with audio apps like
>> > mplayer
>> > or
>> > mpd. recently however i'm experiencing this strange behaviour. the
>> > app's
>> > volume doesn't match the volume that `mixer` reports. here's an
>> > example:
>
>> CURRENT have VPC.
>> You can completly disable such feature with this sysctl:
>> hint.pcm.X.vpc (default=undefined, enabled)
>>             0=disable, 1=enable
>>             Notes: The only place to enable/disable vpc.
>>                    Enabling/Disabling requires driver reload.
>
>> here is explanation with more details:
>> http://people.freebsd.org/~ariff/SOUND_4.TXT.html
>
>


-- 
Paul