[alsa-devel] how to enumerate useful ALSA devices?
aeikum at codeweavers.com
Wed Jan 4 20:49:56 CET 2012
> The 2008 audio guide recommends
> "Do not use the snd_card_xxx() APIs. For enumerating use
> snd_device_name_hint() (and related functions).
> snd_card_xxx() is obsolete... Bluetooth audio are not included"
> Is that correct advice?
> Wine still uses snd_card, so it knows only about "default" and
> "plughw:x,y". I believe that's wrong but don't know what should be
> used instead in order not to come up with a long list of artificial
> names mentioned in /usr/share/alsa/alsa.conf such as surround51 when
> the poor on-board card knows nothing but 16 bit stereo.
> I'm looking for a list of working devices on this machine, which likely
> should contain "default" (usually leading to PA on a recent Ubuntu machine),
> "plug:dmix" (PA getting out of the way when trying to use other devices),
> "hw:0,0" and presumably not much more.
Bump, still hoping for an answer to this.
I tried experimenting with snd_device_name_hint(). It gave me what
looked like a promising list, consisting of:
This is identical to the list from "aplay -L".
But, passing these to aplay fails if I have PulseAudio running
("device in use"). If I kill PA, then they don't fail, but give
warnings about rate conversion and suggest the plug plugin. So I stick
"plug:" in front of the device name, and they fail again ("unknown
parameter front:CARD"). Clearly I'm doing something very wrong. But I
don't know what!
Then it occurred to me that this list also contains neither "default"
nor the "pulse" device in my asound.conf. Both of these work when
passed to aplay.
Looking to other projects for help, I find that VLC uses the snd_card_
functions, just like Wine currently does. Of course, that fails to
find the "pulse" device from asound.conf. And mplayer's libao2 uses a
couple of hard-coded device names, which is even worse (right?).
So I'm really stuck here. Where am I supposed to get a list of devices
that I can present to the user, including their Bluetooth devices and
virtual devices from asound.conf?
 asound.conf from Arch Linux pulseaudio-alsa package:
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