[linux-audio-user] determining source of latency (system info included)

LinuxMedia linuxmedia4 at netscape.net
Thu Jun 3 20:28:06 EDT 2004

 >>> i am experiencing the "system can't keep up"
 >>> messages like crazy, even recording a single
 >>> first track.
 >>> often when i speak into the microphone, what
 >>> comes out of the speakers sounds like it has
 >>> a crazy chorus effect on it.
 >>> i also wonder what the correct settings to use in
 >>> the alsamixer gui are.

 >> I also get chorus-like (and echo-like) effects
 >> when I'm doing...
 >> ecasound -i:/dev/dsp -o:/dev/dsp
 >> (in from card 1 and directly out to card 1)
 >> I have a soundblaster and this is what I did...
 >>- In KAMix
 >>     - Go to the "Capture" tab
 >>     - Turn off "Activate" under the "Wave Capture"
 >>       control (make sure both are "unchecked")
 >>- In alsamixer
 >>     - (de)activate capture on the "Wave" control
 >>       (Use the left or right keys to move to
 >>       "Wave", then press the space bar and it will
 >>       toggle "CAPTUR" at the top of the "Wave" "level
 >>       slider" (or whatever you call it)

> i'm afraid i don't even see a "Wave" item.  

 > i'm using gnome-mixer and alsamixer-gui.

Some of the mixers don't show all the controls.
If you You're running the KDE Desktop, then get
"KAMix". Otherwise try "QAMix" (KAMix is "QAMix
for the KDE Desktop"). If not then go to a shell
and type "alsamixer" (if installed) and use
my above approach. alsamixer will show all the
controls that your card offers (and even ones
that your card doesn't offer)

Again... QAMix or KAMix not only show all the
controls, but they're (much) easier to understand
than alsamixer.

> i am using "Line" for the input,

Stick with "line in". The mic input
is usually crappola.

> but i also seem to
> need something called "ADC" selected for any capture
> to happen at all.  but it always sounds horrendous.

I haven't run into that situation. I can't comment
on it.

> i don't know if all this is a separate issue from the
> latency issue or not.

When I did (the above), the sound improved immensly.
But I haven't done any recording since discovering
this. But I wouldn't be surprised if it is. If I'm
not mistaken, I think that the sound is being moved
around in channels that they don't need to be. And
with this, you may be saturating the situation with
too much sound. Anyways, I know the sound improved
when I shut off Wave Capture. There was no more
chorus-like effects.

Other things improved, but I don't want to confuse
the (current) set of issues we're trying to solve
for you.

Let me know how everything works out.


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