[linux-audio-user] multichannel Audacity testing

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Subject: [linux-audio-user] multichannel Audacity testing
From: Daniel James (daniel_AT_mondodesigno.com)
Date: Wed May 07 2003 - 12:13:26 EEST


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


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