Comments on: lsof |grep snd — how to free a Linux sound device

By: Aistis

Aistis — Thu, 25 Feb 2010 16:57:58 +0000

I luv this tutorial.. OneMegaThanksToYou !!!

By: theme

theme — Thu, 18 Jun 2009 14:28:21 +0000

Kamil: completely agree with you, that is a so dirty solution, but as you point it works. The pitty is that Matlab/java and/or Alsa team doen't manage to fix it. Let's hope they get any solution. Linux is for work and have fun and multitasking system so, we should be able to do both, working with matlab while enjoying great music.

Anyway thanks for the tip, i liked itvery much, sorry for the absence but i've been working in other issues, and now i've already focused again in matlab : )

THNX again

By: Kamil

Kamil — Sat, 09 May 2009 02:07:25 +0000

Hi Dimitris, in all likelihood your sound card can play and record at the same time, f.e. I can use, at the same time, mplayer for playback and gnome-sound-recorder for recording, without errors. The only thing that can get tricky are the mixer settings. Try un-muting all devices using alsamixer and set all the volumes to maximum to get started.

By: Dimitris

Dimitris — Fri, 08 May 2009 20:49:33 +0000

Any solution for me?

By: Kamil

Kamil — Fri, 01 May 2009 11:44:16 +0000

Good question, lets try a few things… if I play music using mplayer and then use say play (a sox based playback script) to play another audio file. Both play fine.

If I play music using mplayer and the start matlab and try to play any audio (even after mplayer finished) it fails like so:

>> x=wavread('sp10.wav');
Warning: The playback thread did not start within one second.
> In audioplayer.playblocking at 35
In audiovideo/private/playsnd at 16
In sound at 46
In soundsc at 48
>> Unable to open the audio device for playback: javax.sound.sampled.LineUnavailableException: Audio Device Unavailable

To get it to work, I have to quit matlab and start it again. On the other hand, if I start matlab first and then try to play audio using mplayer, then mplayer fails to play — it simply sits there with the following prompt: Starting playback…

Ok, so as mentioned previously it is matlab's java based playback libs that simply requires exclusive access to the audio device. A bit of googling confirms that this is a common problem, and that java and/or alsa are at fault for not handling these things nicely.

Alright, if I had to do it, then my hack would be as follows. I would create a matlab wrapper function file called play.m somewhere in matlab's path. The content of play.m would be something like this:

% Saves audio data to a wav file before playback.
%
% audio - audio samples
% fs - sampling rate (Hz) [default: 8000]
% nbits - precision (bits) [default: 16]
% wavfile - filename for the wav file [default: '/tmp/tmp.wav']
%
% usage: play(audio, fs, nbits, wavfile)

function play(audio, fs, nbits, wavfile)

% parse input arguments or use defaults
switch(nargin)
case 1, wavfile='/tmp/tmp.wav'; nbits=16; fs=8000;
case 2, wavfile='/tmp/tmp.wav'; nbits=16;
case 3, wavfile='/tmp/tmp.wav';
case 4,
otherwise, error(sprintf('usage: play(audio, 8000, 16, "/tmp/tmp.wav"\ntype: help play for further details…'));
end

% save audio to file, scale prior to writing to avoid clipping
audio = 0.999*audio/max(abs(audio));
wavwrite(audio, fs, nbits, wavfile);

% playback the audio
if(exist(wavfile, 'file'))
syscmd = sprintf('mplayer %s', wavfile); % uses mplayer for playback
%syscmd = sprintf('play %s', wavfile); % uses sox play for playback
system(syscmd);
else
error(sprintf('%s: file not found.', wavfile));
end

% EOF

In matlab, help play gives the following:

>> help play
Saves audio data to a wav file before playback.

audio - audio samples
fs - sampling rate (Hz) [default: 8000]
nbits - precision (bits) [default: 16]
wavfile - filename for the wav file [default: '/tmp/tmp.wav']

usage: play(audio, fs, nbits, wavfile)
Overloaded methods:
audiorecorder/play
audioplayer/play

So make sure that your play.m is in the path before the other ones, or call it something else…

Ok, it is not pretty, but it works.

Kamil

By: theme

theme — Fri, 01 May 2009 09:36:08 +0000

First of all,this post is awsome and i've learned great and useful things but, i wonder if there's any way to be able to work with matlab (playing sounds) and listening music with another program (f.i. firefox and streaming) without having to kill one of both.

By: Dimitris

Dimitris — Thu, 23 Apr 2009 17:10:36 +0000

Indeed it worked!
This means that i can't hear music at the same time that
i want to speak with the microphone?

I had this problem for a long time, and after i used the commands above
for the first time my aMSN closed alone, and when i reopened it (without music)
the recording and the camera, worked properly. But when i re opened music
i had again the same error " Could not gain access to /dev/dsp for writing." .
Do i have to follow this procedure every time that i open the music?

PLz answer to my mail or here…
Thanks in advance

By: Kamil

Kamil — Wed, 21 Jan 2009 03:00:02 +0000

Kim, take a look at: http://linux.dsplabs.com.au/no-volume-control-gstreamer-plugins-and-or-devices-found-no-sound-or-voume-control-bug-on-ubuntu-p31/

By: Kim

Kim — Tue, 20 Jan 2009 22:32:12 +0000

I have no idea what Im doing here, I keep getting "no volume control gstreamer plugins and or devices found" as an error message when I click on my speaker icon!! Can anyone explain in LAYMEN terms how I fix this pleeeease????

By: Wallace Silva

Wallace Silva — Thu, 04 Dec 2008 15:43:51 +0000

solution in my pc
i did have to install libsnack to alsa

# apt-get install libsnack2-alsa

and solved.

tks.

By: cynthia

cynthia — Tue, 28 Oct 2008 12:23:11 +0000

wow! I've been searching the net to find solution to this problem. My transcription software sometimes runs and sometimes not. A hassle when transcription assignment arrives; but this article saved me! Thanks a lot and more power for giving this support!

By: craig

craig — Fri, 17 Oct 2008 17:40:05 +0000

Thanks a bunch, I always resorted to closing down every program, or even rebooting. More uptime for me now!

By: Miguel

Miguel — Tue, 01 Jul 2008 22:11:02 +0000

Excellent!… It worked!…
I had to do one step more: locating the program lsof using the command: whereis.

By: Kamil

Kamil — Fri, 25 Apr 2008 03:20:47 +0000

what is the laptop model number and what is the sound card type? since your audio device is does not get detected by default it will be a fair bit trickier to get it to work… where I would start is googling to see if others have done it… for example I would search for "linux audio dell 9300 audigy sound blaster".

By: Anonymous

Anonymous — Fri, 25 Apr 2008 01:03:02 +0000

when i run this command:

cat /proc/asound/cards

the output is:

no soundcars

But i belive that i have sound card coz my laptop sound is working when i use windows

help me