Mysteries of sound in Fedora-9

[stan]

Timothy Murphy wrote:
> I'm still baffled by sound on my Fedora-9 + KDE ThinkPad T23.
> What puzzles me is that sound never works when I logon, 
> but starts at some point when I play with the sound settings.
>
> Today I muted the Front bar, and then unmuted it,
> and sound started working.
at this point, when it is working, run /sbin/alsactl store.  That will 
store the settings that are currently working as the setup to use at 
next startup.  If it isn't working again at startup, run alsactl restore 
to get back your settings.  If that doesn't work, something is blocking 
the sound card.
>
> But what I'd like to know is how I can test the sound system,
> to see where the problem arises?
One thing that gives a quick picture of your sound system is to run the 
script at this location
http://hg.alsa-project.org/alsa/raw-file/tip/alsa-info.sh
The script scans your machine and extracts out things relevant for 
diagnosis and puts them on a website.  It gives you a link to the 
information that you can post here or use yourself.

Another thing is to use aplay (man aplay).

In your case aplay -v -D plughw:0,0 some.wav should play something.
> Is it at driver level?
Unlikely in your case as sound works even though you have to fiddle a 
bit.  If the driver was bad, it would be bad. 
> Or is it something to do with pulseaudio?
Might be this as it blocks access to alsa when it runs.  Some things 
work with that, some don't.
> Or is it something to do with xine?
Not likely.
> What I'd really like is a suite of test programs
> which will check each stage along the "sound stack".
They don't exist (yet).  It is a bunch of reading and coding.  Alsa gets 
deep really fast, so it is a job to come up to speed unless you have 
familiarity with the jargon.
>
> Someone mentioned trying something like "cat foo.ogg > /dev/dsp".
> In my case, when sound is working this produces a white noise.
> Is this testing the sound driver
> (in my case snd_intel8x0 , I assume) directly?
>
> I guess what I'm looking for is a Fedora Sound FAQ,
> with Q1: I have no sound, what can I do?
The first thing is run the script above, and look at the output.  Once 
you have some understanding of alsa, it can point you to the problem.