Running mplayer at boot with systemctl. fails with alsa-lib error

Question

I am running Arch ARM on a raspberry pi and would like to use it as a headless music player.
I am trying to run mplayer in slave mode at start up and have in read from a fifo pipe which I could write to over SSH.
I have written this mplayer.service file:
[Unit]
Description='mplayer service'
[Service]
ExecStart=/usr/bin/tmux new-session -d -s mplayer 'mplayer -idle -input file=/systemdservice/mplayerfifo /systemdservice/1.mp3 &> /systemdservice/mplayererror.log'
User=user
Type=forking
[Install]
WantedBy=multi-user.target
When I start this service with 'sudo systemctl start mplayer.service' I get the following output:
MPlayer SVN-r36285-4.8.1 (C) 2000-2013 MPlayer Team
Cannot test OS support for SSE, disabling to be safe.
205 audio & 424 video codecs
mplayer: could not connect to socket
mplayer: No such file or directory
Failed to open LIRC support. You will not be able to use your remote control.
Playing /systemdservice/1.mp3.
libavformat version 55.7.100 (internal)
Audio only file format detected.
Load subtitles in /systemdservice/
==========================================================================
Opening audio decoder: [mpg123] MPEG 1.0/2.0/2.5 layers I, II, III
AUDIO: 44100 Hz, 2 ch, s16le, 32.0 kbit/2.27% (ratio: 4000->176400)
Selected audio codec: [mpg123] afm: mpg123 (MPEG 1.0/2.0/2.5 layers I, II, III)
==========================================================================
[AO OSS] audio_setup: Can't open audio device /dev/dsp: No such file or directory
[AO_ALSA] alsa-lib: confmisc.c:768:(parse_card) cannot find card '1'
[AO_ALSA] alsa-lib: conf.c:4248:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
[AO_ALSA] alsa-lib: confmisc.c:392:(snd_func_concat) error evaluating strings
[AO_ALSA] alsa-lib: conf.c:4248:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
[AO_ALSA] alsa-lib: confmisc.c:1251:(snd_func_refer) error evaluating name
[AO_ALSA] alsa-lib: conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
[AO_ALSA] alsa-lib: conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
[AO_ALSA] alsa-lib: pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM sysdefault
[AO_ALSA] Playback open error: No such file or directory
AO: [pulse] Init failed: Connection refused
[JACK] cannot open server
[AO SDL] Samplerate: 44100Hz Channels: Stereo Format s16le
[AO_ALSA] alsa-lib: confmisc.c:768:(parse_card) cannot find card '1'
[AO_ALSA] alsa-lib: conf.c:4248:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
[AO_ALSA] alsa-lib: confmisc.c:392:(snd_func_concat) error evaluating strings
[AO_ALSA] alsa-lib: conf.c:4248:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
[AO_ALSA] alsa-lib: confmisc.c:1251:(snd_func_refer) error evaluating name
[AO_ALSA] alsa-lib: conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
[AO_ALSA] alsa-lib: conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
[AO_ALSA] alsa-lib: pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM sysdefault
[AO SDL] Unable to open audio: No available audio device
DVB card number must be between 1 and 4
AO: [null] 44100Hz 2ch s16le (2 bytes per sample)
Video: no video
Starting playback...
A: 0.1 (00.0) of 1567.0 (26:07.0) ??,?% [J
A: 0.1 (00.0) of 1567.0 (26:07.0) ??,?% [J
MPlayer interrupted by signal 2 in module: play_audio
A: 4.5 (04.5) of 315.0 (05:15.0) 1.7% [J
Exiting... (Quit)
mplayer starts within a tmux window but I don't get any sound and have to stop mplayer from within tmux with CTRL+C which ends the process.
interestingly  when as user I run:
/usr/bin/tmux new-session -d -s mplayer 'mplayer -idle -input file=/systemdservice/mplayerfifo /systemdservice/1.mp3 &> /systemdservice/mplayererror.log'
it works perfectly.
If in mplayer.service I change the user  to root it also works perfectly.
user is a member of audio group.
I am confused as to what is causing this problem which appears due to a limit of users audio group privilages when a process is started via systemd.
Any help appreciated.
Thanks in advance.
Last edited by epoynton (2013-10-30 21:44:43)

Answer 1

Have you tried setting the audio output driver for mplayer explicitly? See:
mplayer -ao help
I would try
-ao alsa
ALSA doesn't use /dev/dsp anymore I don't think. On a Pi you will also need to make sure the mixer is set with amixer like:
amixer cset #
You can use
aplay -l
to see the available device IDs etc.
Hope this helps.
Last edited by Minsc (2013-11-11 17:02:08)