[linux-audio-user] multichannel Audacity testing

[Daniel James]

We've done our first night of testing with the Delta 1010, with mixed 
results. The hardware is:

Asus P4PE motherboard (Intel 845 chipset)
Pentium IV 2.4B (2.4GHz, 533MHz FSB)
Seagate Barracuda IV 80GB
M-Audio Delta 1010 (IRQ 9)
Matrox G550 Dual DVI (IRQ 10)
SB Live (IRQ 11, for soundfonts in hardware with external MIDI 
keyboard)
All other hardware disabled in BIOS (USB, serial ports, parallel port, 
onboard sound etc) except for Broadcom onboard LAN sharing IRQ 9 - 
configured, but disabled for recording session with:

ifconfig eth0 down

cat /proc/interrupts

now shows only Delta 1010 on IRQ 9

Software:

Linux Mandrake 9.1 upgraded from 9.0
Multimedia patched 2.4.21-pre kernel
ReiserFS filesystem on / and /home
ALSA upgraded to 0.92 with Cooker RPMs
envy24control compiled from alsa-tools 0.93 tarball
wxGTK 2.40 compiled from tarball
Audacity 1.1.3 compiled from tarball 

With the Delta 1010 and two input tracks selected in the Preferences, 
it all works fine. Four input tracks also works. Select eight input 
tracks and it works fine initially, but after a while something weird 
happens to the recorded input - I've never seen this behaviour with 
Audacity in any other context. 
  
Suddenly the waveform is drawn as a rapid series of the same shape. 
Playing the track back, it sounds as it looks:

da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-

Can anyone replicate this bug, if it is a bug? With full duplex 
enabled, it was even more flaky. I did compile Audacity before the 
upgrade to Mandrake 9.1, so this may be related. On another computer 
with just a normal two-channel soundcard, Audacity can dummy 'record' 
eight channels in full duplex without problems, but then it isn't 
actually doing much work. 

Next, we're going to try Thac's RPMs of Audacity 1.1.3 and at least 
one other multichannel recorder app to see if this is my lack of 
compilation skills, a system problem or an Audacity problem.

Cheers

Daniel