Re: [Alsa-user] Best supported cards?

[James S. <Sha...@ea...>]

> Here's what I have not been able to get to work:
> Full duplex,

Not sure about the full duplex part, as not all cards are full duplex.  My M-Audio Delta 44 says Full Duplex on the box.  And seems to be just that.  My laptop(ATI IXP) on the other hand can do full duplex, BUT... there's some bleed over of the playing track into the recorded track.  And there's just too much noise from the plug-in power / bias voltage that powers electret style microphones.  You might also try disabling the onboard soundcard in the bios/cmos.  Or otherwise indexing the Audiophile's alsa driver to card 0.  Or using defaults.pcm.card # in your asoundrc, where # is the card you want to use by default as shown in /proc/asound/cards.

# in /etc/modprobe.d/alsa_custom
# my own non distro supplied modules.conf style configuration

# for my Delta 44
options  snd-ice1712      index=0

# for my Mobile Pre
options  usb-audio        index=2
# note: my ati ixp takes up 0 AND 1 because of the ac97 modem part.

# end alsa_custom


# in ~/.asoundrc

# when I'm too lazy to use jackd or re-index my drivers
# or customize whatever sound app to use something other
# than the default card(0).
defaults.pcm.card         2
# where 2 is the card that I want to use
# as listed in /proc/asound/cards

# end .asoundrc



> Recording in Audacity without introducing clicks into the captured audio,
> Getting Audacity to play without a few second delay and a bunch of clicks and 
> pops,

I've found several things to cause this on my laptop.  The cable running to the mic not quite being fully shielded from RFI.  Even though it may claim to be shielded.  Just don't put the cable on/near your LCD or CRT.  The other cause is lack of realtime scheduling.  i.e. If I'm doing some network traffic while recording.  Solution below (for me anyway).

# in /etc/security/limits.conf

@audio  -  rtprio   99
@audio  -  nice     -10
@audio  -  memlock  unlimited

# end of limits.conf

In conjunction with using jackd -R -d alsa -d hw:0 -r 48000(as a user in the audio group, with the above mods.  Or as root without.), I can get around the clicks and pops.  You may have to recompile audacity to use port audio (v19) to use alsa natively.  If your distro doesn't already do that.  I find ardour to be a little more reliable in the recording department.

On a side note, using a cell phone in close proximity to my audio gear seems to introduce some RFI to my stereo.  Even having a cell phone that's on, but not currently in use will do some of that at random intervals.  I know it's the cell phone because moving it to the other room stops affecting the gear in my room, and starts affecting it in the other room.  Sort of a morse code D D as heard on my speakers when stereo is on and the cell phone is close enough to it.  Just random static when actually using the cell phone.  Apparently cell phones put out quite a signal.

HTH