[SOLVED] USB sound card problems and audio setup

Question

I want to clarify and correctly set up my ThinkPad T61 sound system finally.
I'm running Arch64 + KDE.
There are two sound cards - the internal HDA Intel and external USB CM118.
aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Set [C-Media USB Headphone Set], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog]
Subdevices: 0/1
Subdevice #0: subdevice #0
card 1: Intel [HDA Intel], device 1: AD198x Digital [AD198x Digital]
Subdevices: 1/1
Subdevice #0: subdevice #0
First of all, why are there both analog and digital subdevices?
I just need playback and/or recording support for these applications: opera, firefox, skype, clementine, mplayer, vmplayer. As high quality as possible.
Per-application sound control would be nice but if that adds too much clutter, I could live without it. No need for audio streaming or any other luxuries.
All the applications should use the USB card whenever it's plugged in. The internal SC should take over when CM118 is unplugged.
The problem is that most of the time it doesn't work. For example, if I plug out the USB card and then run some application like Clementine or Firefox there would be no sound ("connection refused" in Clementine).
Here is my asound.conf:
defaults.pcm.card 0
defaults.pcm.device 0
defaults.ctl.card 0
Also kMix/amix should switch the master channel from HDA Intel Master to C-Media Master automatically. The only way to do this is to write some kind of script, right?
AFAIK the following audio components are installed: ALSA, OSS (for some unknown reason), Phonon, Gstreamer.
I guess I can uninstall OSS without worries as no one seems to need it (checked with "whoneeds").
What about that Phonon? Would it override the asoud.conf if I set default device there? Why there are so many different devices in the Phonon configuration list:
C-Media USB Headphone Set, USB Audio (Default Audio Device)
C-Media USB Headphone Set (USB Audio)
C-Media USB Headphone Set, USB Audio (IECblablabla)
hw:1,0
hw:1,1
default
Intel Analog
Intel Digital
blablalba
And that C-Media triplet for every USB port the CM118 has been plugged in.
Too much confusion! All that mess for just two different cards.
So what is the proper way of setting primary and secondary sound cards in this situation?
Thank you!
Last edited by andrisll (2012-07-19 08:48:28)

Answer 1

I am sorry for my very late response and the lack of structure in my post.
I did some investigation and found a rather acceptable workaround for one of my problems described below.
Here is the basic functionality I need:
1. Automatic (on the fly) switching to the external sound card when it's plugged in and automatic fallback to the integrated SC when usb is unplugged.
2. Automatic (on the fly) switching of the kMix's master channel according to the changes mentioned above.
As for the first problem, I found this udev rule:
KERNEL=="pcmC[D0-9cp]*", ACTION=="add", PROGRAM="/bin/sh -c 'K=%k; K=$${K#pcmC}; K=$${K%%D*}; echo defaults.ctl.card $$K > /etc/asound.conf; echo defaults.pcm.card $$K >>/etc/asound.conf"
KERNEL=="pcmC[D0-9cp]*", ACTION=="remove", PROGRAM="/bin/sh -c 'echo defaults.ctl.card 0 > /etc/asound.conf; echo defaults.pcm.card 0 >>/etc/asound.conf'"
This solution has some disadvantages but it is acceptible. If you know of any better solution, please tell me.
For the second problem, I found this script which uses qdbus org.kde.kmix /Mixers org.kde.KMix.MixSet.setCurrentMaster method to set the master channel. However, I think that constant monitoring for the usb SC being plugged is not very effective. So I thought appending the following code to the second line of the previous udev rule would do the work:
, RUN+="/usr/bin/qdbus org.kde.kmix /Mixers org.kde.KMix.MixSet.setCurrentMaster "ALSA::C-Media_USB_Headphone_Set:1" "Speaker:0""
But that results in some weird behaviour: master channel stays the same but there would be three new tabs in the kMix window now: USB Set", USB Set# and USB Set$.
Here's what log messages tell us:
07/14/12 12:25:13 PM localhost kernel [10889.749048] usb 3-1: new full-speed USB device number 13 using uhci_hcd
07/14/12 12:25:14 PM localhost kernel [10889.914921] input: C-Media USB Headphone Set as /devices/pci0000:00/0000:00:1a.1/usb3/3-1/3-1:1.3/input/input21
07/14/12 12:25:14 PM localhost kernel [10889.915454] generic-usb 0003:0D8C:000C.000C: input,hidraw0: USB HID v1.00 Device [C-Media USB Headphone Set ] on usb-0000:00:1a.1-1/input3
07/14/12 12:25:14 PM localhost mtp-probe checking bus 3, device 13: "/sys/devices/pci0000:00/0000:00:1a.1/usb3/3-1"
07/14/12 12:25:14 PM localhost mtp-probe checking bus 3, device 13: "/sys/devices/pci0000:00/0000:00:1a.1/usb3/3-1"
07/14/12 12:25:14 PM localhost mtp-probe checking bus 3, device 13: "/sys/devices/pci0000:00/0000:00:1a.1/usb3/3-1"
07/14/12 12:25:14 PM localhost mtp-probe checking bus 3, device 13: "/sys/devices/pci0000:00/0000:00:1a.1/usb3/3-1"
07/14/12 12:25:14 PM localhost mtp-probe bus: 3, device: 13 was not an MTP device
07/14/12 12:25:14 PM localhost mtp-probe bus: 3, device: 13 was not an MTP device
07/14/12 12:25:14 PM localhost mtp-probe bus: 3, device: 13 was not an MTP device
07/14/12 12:25:14 PM localhost mtp-probe bus: 3, device: 13 was not an MTP device
You see, the probe thing is running multiple times!
And here is an excerpt from udev debugger:
starting '/usr/bin/qdbus org.kde.kmix /Mixers org.kde.KMix.MixSet.setCurrentMaster '
'/usr/bin/qdbus org.kde.kmix /Mixers org.kde.KMix.MixSet.setCurrentMaster '(err) 'Could not connect to D-Bus server: org.freedesktop.DBus.Error.NotSupported: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11'
'/usr/bin/qdbus org.kde.kmix /Mixers org.kde.KMix.MixSet.setCurrentMaster ' [2769] exit with return code 1
'/usr/bin/qdbus org.kde.kmix /Mixers org.kde.KMix.MixSet.setCurrentMaster '(err) 'Could not connect to D-Bus server: org.freedesktop.DBus.Error.NotSupported: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11'
Some kind of X11 problem... And also happening twice! Why?
Running the setCurrentMaster method in terminal works very nicely, so the problem must be the way udev runs it.
One last thing - sometimes the usb SC automatically reconnects (disconnects and connects). I read somewhere that most probably the usb device makes the trouble, but maybe there are other possiblities?
Last edited by andrisll (2012-07-14 10:04:16)