Sound permission problem - solved

Lars Bjørndal lars.bjorndal at broadpark.no
Fri Nov 30 09:19:35 UTC 2007


lars.bjorndal at broadpark.no (Lars Bjørndal) writes:

> "Mikkel L. Ellertson" <mikkel at infinity-ltd.com> writes:
>
>> Lars Bjørndal wrote:
>>> lars.bjorndal at broadpark.no (Lars Bjørndal) writes:
>>> 
>>>> Hi!
>>>>
>>>> I'm running Fedora F7, without X. I'm able to do 'mplayer <url>' for
>>>> one user at a time. However, I'm not able to do 'mplayer <url>' for
>>>> one user, and then 'mplayer <another-url>' as another user. Then I get
>>>> the following error message:
>>>>
>>>> [AO_ALSA] alsa-lib: pcm_dmix.c:831:(snd_pcm_dmix_open) unable to
>>>> create IPC semaphore
>>>> [AO_ALSA] Playback open error: Permission denied
>>>>
>>>> It's not important to me to play mplayer that way, however, I want to
>>>> be able to run speech-dispathcer (which, BTW should have an rpm pacage
>>>> for Fedora) and play mplayer at the same time. How could I solve this
>>>> permission problem?
>>>>
>>>> I've tried to put in /etc/security/console.perms.d/50-default.perms:
>>>>
>>>> <console>  0666 <sound>      0600 root,
>>>>
>>>> and ls -al /dev/audio gives:
>>>>
>>>> crw-rw-rw-+ 1 lrs root 14, 4 2007-11-29 10:00 /dev/audio
>>>>
>>>> Lars
>>> 
>> 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

I found the solution here: http://mpd.wikia.com/wiki/Configuration. I
created the file /etc/asound.conf, with the following content:

pcm.dmixer {
  type dmix
  ipc_key 1024
  ipc_key_add_uid false
  ipc_perm 0666                       # mixing for all users
  slave {
    pcm "hw:0,0"
    period_time 0
    period_size 1024
    buffer_size 8192
    rate 44100
  }
  bindings {
    0 0
    1 1
  }
}

pcm.dsp0 {
  type plug
  slave.pcm "dmixer"
}

pcm.!default {
  type plug
  slave.pcm "dmixer"
}
pcm.default {
  type plug
  slave.pcm "dmixer"
}
ctl.mixer0 {
  type hw
  card 0
}

Lars




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