Joined: 21 Jul 2002
|Posted: Mon Mar 25, 2013 9:35 pm Post subject: "Unknown PCM" issue with LADSPA? Here's a solution
|I was having issues with my LADSPA config. I'm using alsa (1.0.25-r1) and pulseaudio (2.1-r1).
In short - I was able to use my own PCM devices, set in ~/.asoundrc, as root, but not as a normal user. Even though I had already added the user into the audio group, when I tried something like speaker-test -c2 -Dladspa, I always got an error that said something like Unknown PCM ladspa; Playback open error: -17 File exists.
After a lot of trial and error (which felt like searching for a needle in a haystack), I solved this issue as follows. It seems that ~/.asoundrc (as well as /etc/asound.conf) is being loaded twice: once by /usr/share/alsa/alsa.conf and once by /usr/share/alsa/alsa.conf.d/51-pulseaudio-probe.conf.
As I said, I'm using pulseaudio, so I ended up editing /usr/share/alsa/alsa.conf and I commented line 19, which now contains #~/.asoundrc. Now it'll just be loaded once which is how it should be - no more File exists error.
This was enough to get my LADSPA PCMs to work again. Yay! I'm sharing this titbit of info lest anyone else who faces this problem has to go through the same boring trial-and-error search routine as I had to just now.
Additionally, these days I'm just way too much AFK. That won't change any time soon. Normally I'd report this on the bug tracker but I'm not sure (and unable to search) whether it is actually is a bug and whether the redundant loading of ~/.asoundrc can be replaced by something more accurate -- either by adding some kind of "has it already been loaded" test, or by commenting the line by default in either of said files.
Diplomacy is the art of letting the other party have things your way.
-- Daniele Vare