FAQ001
From the ALSA wiki
| The FAQs have been reorganized. The new location of this question is FAQ#How can I see which audio [pcm], midi [seq] and mixer [ctl] devices my ALSA installation sees? |
How can I see which audio [pcm], midi [seq] and mixer [ctl] devices my ALSA installation sees?
You can't see all of them. ALSA has no complete device enumeration scheme. This is a failing of the current (2006-06) state of the project.
You can get ALSA to tell you what pieces of hardware it knows about, but this won't tell you about dmix and other software interfaces, and you have to interpret the list of hardware devices into ALSA device labels (such as hw:0,0 or default:0) yourself.
Looking via /proc
The hardware info is listed in ALSA's /proc interface. Use...
cat /proc/asound/cards
to see which cards are seen by your ALSA installation. Use...
cat /proc/asound/devices
to see which devices these cards have.
If you get errors like "No such file or directory" on the above commands, then your ALSA modules are probably not yet loaded (or perhaps you haven't even built and installed ALSA, or maybe you typed something wrong). Try browsing in /proc to see which other info your kernel provides. If there is no /proc/asound directory, ALSA is almost certainly not installed and running. Also check Takashi's explanation of /proc in the AlsaTips section.
proc asound documentation tries to explain what the output means and has some examples of how to translate the hardware device names into the ALSA device labels. Takashi's explanation of /proc in the AlsaTips section might also help.
In future /proc will be used for process information only, and the place to look for ALSA info will be sysfs. In the 2.6 kernel source, there's a file called Documentation/filesystems/sysfs.txt with some info about this. You can also use the aadebug script to provide a brief snapshot of your system suitable for emailing to someone else for help.
