Sound permission problem

Mikkel L. Ellertson mikkel at
Fri Nov 30 14:29:28 UTC 2007

Lars Bjørndal wrote:
>> Dumb question - is the first user's mplayer closed before the second
>> user tries to run their copy of mplayer? I am not familiar with the
>> error message, but I am guessing that the problem is that something
>> has a connection to the mixer open, and so you can not open another.
>> If that is the case, you may be able to do something using the jack
>> add-ons to alsa.
> To your question: I tried to run two instances of mplayer at the same
> time. And: I'm able to run two mplayer sessions at the same time from
> the same user. The problem raises if I first start mplayer for user1,
> then switches to user2 and start mplayer. Mplayer is still running on
> user1. Any suggestions?
> Lars
From your description, I suspect that the problem is not in the
permission of the ALSA devices, but in what the error message called
"IPC semaphore". I am guessing that this is a socket of some kind
that lets mplayer communicate with the mixer controls. Mplayer if
probably creating it in /tmp, and because user 1 has one there, user
2 can not create one, and does not have permission to use the one
created by user 1. (mplayer is probably trying to use the same name.)

Now, there is something called jack that lets you get fancy with the
ALSA and different audio sources. Think of it as an audio patch
panel. There is also a mplayer plugin that gives you a jack output.
I have never tried it, but it may let you combine the mplayer output
from two different users. I know it will let you mix the audio
output from several programs, each with its own level control. I do
not know if it will work with the speech-dispathcer. On the other
hand, if speech-dispathcer is not trying to control the mixer, it
may work with your current setup.


  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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