[LAU] lost sound (it had been working) -fixed !!!

[Reid Vail]

Well, that fixed it. 

I captured the asound.state file from the liveCD and ran xxdiff against 
that file and the one from my production OS.  Although the files were 
the same size they were different in config.  Honestly, I haven't 
drilled that deeply but xxdiff shows right where to look.

I backed up the asound.state and copied the working version to that same 
name, ran alsactl restore and ... that's it.

So I'll try to go back and understand what changed.

Much obliged to everyone, and thanks for your patience.

Reid Vail

James Cameron wrote:
> On Tue, Jan 20, 2009 at 07:48:01PM -0500, Reid Vail wrote:
>   
>> I loaded Knopix 5 .1 and the sound worked perfectly right away...and  
>> that's not a very old version ( < 2 years I think).  So then I loaded  
>> the Ubuntu 8.10 liveCD and it also worked fine.
>>     
>
> Interesting, and useful data.
>
>   
>> So this is not a speaker problem or a hardware (MB "soundcard" problem)  
>> and it's not an old software vs. new software problem.  It can only be a  
>> configuration problem.
>>     
>
> Yes, that seems likely, unless your software is different to the Ubuntu
> 8.10 liveCD kernel, such as may happen if you have applied updates.
>
>   
>> Thinking of trouble-shooting scenario, I wonder if it makes sense to   
>> reload the liveCD, capture the config and then boot off the HD and  
>> compare what's in place to what worked on the liveCD?  If you think  
>> that's worthwhile can you let me know which configuration settings to  
>> capture.
>>     
>
> Okay.  We've been having this problem on the OLPC XO lately, so I'm up
> on it.  All the ALSA controls are stored on shutdown and restored on
> boot, for most distributions of Linux.  The command
>
> "alsactl store" saves the controls, and the command
>
> "alsactl restore" restores them.
>
> There's a --file option for telling it where to store into or restore
> from.  The default location is distribution specific.  Fedora in one
> place, Debian in another.  Ubuntu is derived from Debian.  It is easy to
> find, just run the command
>
> 	strace -e open alsactl store
>
> On an Ubuntu 8.10 test system here, the file is
> /var/lib/alsa/asound.state
>
> The file is text, in my experience, and can be compared with previous
> files.  The file content is sound card and driver version specific, but
> driver authors tend to accept the old file in new versions of driver.
> (Gross simplification).
>
> So on the assumption that your problem is ALSA controls, do a store in
> each of the operating system environments you have tried, and compare
> the output mechanically, e.g. with the diff command.  There are some
> handy graphical diff programs around, I use kdiff3 or emacs.  Capture
> all the files first before making any change, so that you can tell why
> it is happening.
>
> If you see a difference, try to understand it.  Try to restore that file
> on the non-working environment.  It may fix the problem.
>
> If you see a difference in that there are more or less controls, then
> the cause will be change in the driver between the different
> environments.
>
> If you see no difference at all, then the cause of your problem won't be
> ALSA controls, and you should look at drivers.
>
> There yet may be other causes.
>
>