[linux-audio-user] A most bizarre problem.

[Jos Laake]

Malcolm Baldridge wrote:

Hi again Malcolm,

I wrote earlier:
>>In my mixer (I'm using the KDE sound mixer) there are a bunch
>>of sliders, some with record buttons underneath.  If I use the
>>line-in slider ('Line' on my mixer) with the record button on,
>>I get the results you're talking about.
>>
>>BUT!!!
>>
>>If I turn on the record button under the 'Line' slider, but
>>leave the slider all the way down and instead use the slider
>>marked 'IGain', then my line-in signal goes into the recording
>>but *NOT* directly through to the line out. 

Malcolm wrote:
> Hrm, I have two problems here.
> 
> 1) This machine does not have X11, and cannot have X11 on it.  Let alone KDE.
> 
> 2) I don't see "IGain" in the alsamixer at all.  I think if I turn down the
> slider all of the way for "Line-In" I don't get any recorded audio from LINE-IN.

<...snippage...>

> I think I understand what you've done though, and I could probably figure
> out how to replicate how you've setup your volume controls with alsamixer's
> understanding of how things are configured on the sound hardware.  But it
> will be alot of trial-and-error. :(   Alas, this setup is used during the
> day so such experimentation will have to wait.  Maybe some kind soul knows
> what "IGain" is under the alsamixer?  Maybe it's "Capture Volume"?

Yes, it is.  It's kinda tricky, but I took the time to dink
around with alsamixer to try to get the same results.  Here's
what I came up with:

You need to use the slider marked 'line'.  Turn off the mute
(using the 'M' key so that the -MM- at the top pf the slider
is gone).  Turn on recording (they call it capture) by pressing
the space bar.  Turn the volume on this slider ALL THE WAY DOWN
so that the numeric readout shows "0<>0".  Scroll left among the
sliders using the right arrow key until you get to the slider
marked 'Capture'.  Unmute ('M') it and also select record on this
one. At this point, the top of the slider should show 'CAPTUR' in
red on BOTH the 'Line' slider *and* the 'Capture' slider.  Now
use the volume on the 'Capture' slider to set the recording
volume, and Voila!  You should get the line input in your
recording but NOT mixed directly through to the output.

Another bizarre little effect;  the 'Line-in' slider just to the
right of the 'Line' slider seems to add some kind of boost to
the input gain.  You might want to play around with that.  The
alsamixer calls it 'Line-In As Surround' in the caption in the
upper left of the screen, but that seems kinda bogus.  Also, the
on/off (controlled by the 'M' key) seems to be reversed on my
system which is to say, the boost appears to be on when alsamixer
sez it's off and off when alsamixer sez it's on.  Weird.

> OK, maybe I can get what I want my manually editing the asound.state file
> and doing an alsactl restore... So much for the GUI! :)

I've never messed much with alsamixer before (and don't care to
mess much more with it really.)  So you'll have to figure out
how to save your settings.

> I'd really like to see the source document referenced by the engineers who
> setup the volume control software for ALSA/OSS, because the appearance is
> one of total chaos and disorganisation.  This isn't rocket science, and we
> aren't talking about THAT many inputs, outputs, and mixers: there's a
> microphone input (mono, with selectable +20dB boost, and maybe optional
> power), line input (stereo), CD audio (stereo), PCM wave output (stereo),
> master output level (stereo).
>
> So what do I see under alsamixer?  A dozen sliders, some with tri-state
> toggles in addition to levels, with additional state for "record" or
> "capture", with non-obvious interdependencies when I switch "sources".
> 
> Crazy.

Totally crazy.  Alsamixer drove me so nuts that I finally gave
up on it.It's either really buggy or totally non-intuitive or
both.  Maybe somebody who's actually used a soundboard might
wanna try to redefine that interface so that it works like the
rest of us would expect it to?

Or better yet (for me anyway) how about a QT based GUI front
end that actually works like a mixer with mute and record and
solo buttons input select switches and a separate mastering
section?  (Hint:  Put the Master slider on the RIGHT.  That's
how *everybody* else does it.)

> Even the Dark Lord could not have designed a more intentionally
 > obfuscatory interface to audio hardware,

  Well, it certainly blocks the flow of *my* Force. ;-)

~Jos~