Linux sound and multimedia
So. Sudddenly I got no sound from my laptop. I have had ALSA (the “advanced linux sound architecture”) act on me also before, so I suspected the master audio got muted, like happened ages ago.
But no. I search, run alsamixer, the Gnome mixer app, trying to figure out what the problem is.. but nothing. I even tried headphones, to see if the built in speakers are broken. Nothing seems to help. I am really starting to suspect the hardware has simply broken on this Thinkpad. All the software plays just fine, no error messages or anything - I just simply hear nothing. I try spells like “killall esd” and others, but in vain..
Then a friend wonders whether it could be that the digital output toggle of the sound driver would be somehow enabled, thus routing everything there.
I look again at the mixer, and now, once I enable *everything* to show in my mixer app (the defaults had just a main and dsp sliders, which is nice) and I toggle everything. Suddenly I hear music!
So it turns out that “Line Jack Sense” was the thing. Now, why does this get turned on by itself, and why I need to hunt down such a hidden setting anyway is a good question. I think in a few years we can all pat ourselves in the back and laugh at this kind of stuff.. 
August 28th, 2006 at 03:24
I had a problem like that with my laptop. Sound was fine, but DVDs were really quiet. I thought it was just the way the DVDs were designed until I rented The Aviator and it was barely audible. Once I enabled every single mixer control I found out that there were other controls (labelled VIA DXS 1-4) that only affected the sound if it had more channels than stereo.
August 28th, 2006 at 06:47
OMG, thank you! I’ve been without sound a couple weeks! Flash or whatever used /dev/dsp directly worked fine, so I figured it was something to do with esd or alsa.
September 3rd, 2006 at 04:37
I just got the same symptoms just by the same time I found the Line Jack Sense setting and (of course had to…) tried it.
Unchecking it doesn’t help though, but I just now found out that sound is actually working to headphones!
Check all progress here: http://www.ubuntuforums.org/showthread.php?p=1455105#post1455105
September 26th, 2006 at 16:38
The same happens with some VAIO laptops. For some reason you need to toggle the External Amplifier to make sound work. People that don’t know this, might start blaming Linux for not supporting their hardware.