[RESOLVED] Audio Issues - mpd/ladspa crossfeed madness

[gutterslob]

Forgive me if this seems nooby, but it's honestly been a loooong time since I last configured mpd and alsa and may have missed something obvious.

Story goes something like this.
First noticed something was wrong when flash crashed in FF today. Then ncmpcpp didn't start, saying it couldn't connect to MPD. Then found out mplayer had issues also - some ladspa/eq error. That led me to check on alsaequal/libasound2-plugin-equal (alsamixer -D equal), which also reported an eq issue related to ladspa/caps (see second code snippet below). Seemed like a system-wide audio issue, so I removed my .asoundrc and most of the issues were resolved, (obviously I was missing systemwide equalization as a result).... except for mpd.

Has anyone experienced this on mpd recently?

Code: Select all

Setting up mpd (0.17.5-1+b1) ...
[....] Starting Music Player Daemon: mpd/usr/bin/mpd: relocation error: /usr/lib/i386-linux-gnu/i686/cmov/libavcodec.so.54: symbol avpriv_evaluate_lls, version LIBAVUTIL_52 not defined in file libavutil.so.52 with link time reference
 failed!
invoke-rc.d: initscript mpd, action "start" failed.
dpkg: error processing mpd (--configure):

Note that this error was displayed after I had purged mpd and attempted to reinstall it again, but I also received a similar "reallocation error" message when attempting to start mpd prior to the purge. Never received any libavutil or libavcodec errors with mpd before today, so I'm a bit stumped.

Not quite sure which bug all this is related to. Can't seem to find any report relating to my error for mpd, but I found a these for libasound2-plugin-equal and caps.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=685955
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=690115

Fwiw, report #685955 mentions the issue being resolved, and alsaequal being available to the user even without an ~/.asoundrc file now, so I attempted it (since I had removed my ~/.asoundrc to get back audio) again but still got the same error. ;

Code: Select all

geezer@sid:~/ > alsamixer -D equal
Unable to find label "Eq" in plugin library file "/usr/lib/ladspa/caps.so".

Re-instating my ~/.asoundrc caused system-wide audio loss again, like expected.

I know that mpd, libasound2-plugin(s), caps and some ladspa libraries were updated in the last few days - came in via standard apt-get upgrade, not dist-upgrade, just before the current Perl calamity arrived, iirc. Whether all these are inter-related to some degree, or totally unrelated, I do not know. At first glance, the mpd and ladspa/eq issues seem separate from one another, but the timing kind of makes me think otherwise, since they all cropped up at the same time.

My primary issue is getting mpd installed and started now. Only then can I begin to diagnose whether the audio issues are a libasound/ladspa/caps/EQ problem or something else.
It's not a big issue since this is on a laptop that I hardly use and am planning to give away in a few days, but it's still a tad mystifying. I don't seem to have these issues on my BBQ install on another machine, which also has mpd, alsaequal, mplayer and related dependencies installed.

Any advice?

Edit:
Fwiw, I recall this machine did have deb-multimedia sources enabled long ago, but not any longer (removed the mirrors a few months prior). I'd wager that whatever multimedia the standard contrib/non-free Sid repos have now would have superceded the deb-multimedia ones by now, but might it have something to do with the libavcodec/util reallocation errors I'm experiencing with mpd?

[machinebacon]

Educated guess: libasound2-plugin-equal is providing the ladspa/caps libraries in sid, and not the ladspa-plugin package. What if you purge a possibly existing ladspa-plugin package and (re)install libasound2-plugin-equal?

[gutterslob]

Thanks for taking the time, Baconator.

Alas, I've already tried that. Would not have posted the question if I hadn't already exhausted all possible avenues. The libasound2-plugin-equal and caps packages depend on one another, and don't work even if forced installed individually. I haven't tried the sources yet, though.

Getting mpd working was my main priority. I purged all AV related packages (mpd, mplayer, alsa libraries, etc) and started again. It's all installed fine now, though I'm now having issues with starting mpd as user. Should be easily sorted (hopefully) once I find some free time.

I'll wait for the ongoing perl plague to die out first, since I don't want to waste time cross-referencing more packages than necessary. After that, I'll get to the bottom of this ladspa/eq issue and post my findings.

[gutterslob]

Okay, I spoke to someone with similar issues, who in turn spoke to the alsaequal dev. It seems to be a problem affecting people who use ladspa's crossfeed/bs2b ability (great for headphones if you don't have a headphone amp or hardware-based equalizer attached) and have it defined in their ~/.asoundrc and ~/.mpdconf, like myself. Turns out there was a line in one of the sources that got accidentally commented out, resulting in a broken thread.

In Debian package naming terms, this affects libasound2-plugin-equal and bs2b-ladspa packages. The new (pushed yesterday, I believe) libasound2-plugin-equal 0.6-6 resolves this, though you'll need to force-reload alsa and kill all instances of mpd (or reboot) after updating. I'll mark the issue solved.

Edit:
Post updated to fix typos and include version number of libasound2-plugin-equal package which fixes the issue.

[machinebacon]

Thanks for the update - quite exotic :)

[gutterslob]

quite exotic :)

Hah!! You haven't even seen my asoundrc and mpd.conf yet. Ivan would be flabbergasted =P

[ivanovnegro]

^ I know it is solved but the above makes me a little curious. :)

[gutterslob]

^ First, check out these links;
http://www.meier-audio.homepage.t-onlin ... ssfeed.htm
http://bs2b.sourceforge.net/

If you want to give it a shot, read this;
http://takla.wordpress.com/tag/alsa/

It's mostly all on that page. Note that you don't have to build alsaequal from source like the author suggests, since you already have it in Sid (I'm sure you know since you already installed it). Only difference from my setup is that I've got an additional setting in my configs to output digital audio straight to my DAC (Digital Analog Converter) without employing ALSA at all (let the DAC do the work), but I only use that on my office comp. For a standard system without any external DAC and headphone amp, the config from that link should be more than enough.

Also, if you use ncmpcpp, you can enable/disable each of these settings via the "Outputs" screen (key 8):
1. Eq and Crossfeed disabled
2. Crossfeed enabled, Eq disabled
3. Eq enabled, Crossfeed disabled
4. Both Eq and Crossfeed enabled

Pay attention to cpu usage though, since having both crossfeed and equalization enabled will usually cause a slight increase in load. Oldest system I've tried it on is a Dual Core Pentium 2.0GHz (about 6 or 7 yrs old) and I get about 10 - 15% average cpu load playing a 16bit 44.1KHz flac file. With eq and crossfeed disabled, it's around 7 - 10% playing the same file. Not a scientific test by any means, but you might want to take that into consideration if you're concerned about resources remaining for other applications or battery life and whatnot.

Have fun~

Additional reading:
http://forums.gentoo.org/viewtopic-t-71 ... art-0.html
http://www.hydrogenaudio.org/forums/ind ... opic=38291

[ivanovnegro]

Wow! I did not really expect a response on this. :) Thank you Slob!

Who says, we (nix users) are not interested in kick-ass sound configurations. :)