[pulseaudio-discuss] alsa-util.c: Unable to attach to mixer (was: main.c: daemon startup failed.)

Lennart Poettering lennart at poettering.net
Wed Jul 30 10:39:51 PDT 2008

On Sun, 27.07.08 14:42, Ben Finney (bignose+hates-spam at benfinney.id.au) wrote:

> The trouble seems (to my eyes) to begin at the error message "ALSA lib
> control.c:909:(snd_ctl_open_noupdate) Invalid CTL plug:hw:0".

That message is not really important. PA tries to find the right mixer
device for a PCM stream. ALSA has not real API for that. So we try a
few things, which unfortuncately results in a bit of debug messages by

> $ sudo /usr/bin/pulseaudio -vvvv --daemonize=false

-vvvvv? Better safe than sorry, heh?

> I: core-util.c: Successfully gained nice level -11.
> W: main.c: This program is not intended to be run as root (unless
> --system is specified).

Don't run PA as root!

> I: main.c: This is PulseAudio 0.9.10
> I: main.c: Page size is 4096 bytes
> I: main.c: Dude, your kernel stinks! The chef's recommendation today is Linux with high-resolution timers enabled!
> I: module-alsa-sink.c: Successfully opened device plug:hw:0.
> I: module-alsa-sink.c: Successfully enabled mmap() mode.

So you opened plug:hw:0 here. 

> ALSA lib control.c:909:(snd_ctl_open_noupdate) Invalid CTL plug:hw:0
> I: alsa-util.c: Unable to attach to mixer plug:hw:0: No such file or directory
> I: alsa-util.c: Unable to attach to mixer hw:(null): No such device
> I: sink.c: Created sink 0 "output" with sample spec "s16be 2ch 44100Hz"
> I: source.c: Created source 0 "output.monitor" with sample spec "s16be 2ch 44100Hz"
> I: module-alsa-sink.c: Using 4 fragments of size 4408 bytes.
> D: module-alsa-sink.c: Thread starting up
> D: rtpoll.c: Acquired POSIX realtime signal SIGRTMIN+29
> I: module-alsa-sink.c: Starting playback.
> I: module.c: Loaded "module-alsa-sink" (index: #0; argument: "device=plug:hw:0 sink_name=output").
> D: cli-command.c: Checking for existance of '/usr/lib/pulse-0.9/modules/module-hal-detect.so': success
> I: module-hal-detect.c: Trying capability alsa
> D: module-hal-detect.c: Not loaded device /org/freedesktop/Hal/devices/computer_alsa_timer
> D: module-hal-detect.c: Loading module-alsa-sink with arguments 'device_id=0 sink_name=alsa_output.pci_106b_3e_alsa_playback_0'
> D: alsa-util.c: Trying front:0...

And now you are trying to load another module for audio device 0? You
shouldn't have both hal-detect and module-alsa-sink in your startup
script. That usually makes no sense, unless you really know what you
are doing.

> At that point the daemon is running, accepts connections, but
> produces no sound. Eventualy I send it SIGINT and it closes.

Have you set all volume sliders correctly and unmuted all controls?
"alsamixer -c0"?  pavucontrol? Are you sure your stream is connected
to the right device?


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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