Simultaneously recording many tracks

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Subject: Simultaneously recording many tracks
From: Cassettes2CDs (
Date: Wed Jun 09 2004 - 00:42:33 EEST

Dear fellow Ecasounders,

I have this application where I need to record many
many 32-bit/44100 stereo channels at once with some
M-Audio delta 1010LT sound cards.

Here's an example of the command line I use (from a
nest of shell scripts):

ecasound -z:db -r -b 8192 -f 32,2,44100,i -i
"/dev/dsp$dsp" -f 32,2,44100,i -o "$outputfile"

I've managed to get eight stereo channels coming in
this way on a humdrum 1.2 Ghz Athlon with a no-name
hard drive without getting any "hiccups," which is
pretty good.

The Thing Is that the process seems to be very
fragile. If the computer is doing anything else that
involves the disk, then it'll screw up and
occasionally miss some audio and give me a "skip" or
repeated snippet of sound here and there. This is a
commercial enterprise (converting cassette tapes to
CD), so this is bad bad bad.

I really want to record more channels at once, since
it'll minimize the number of recording computers I'll
need. Synchronization -between- those channels isn't

I've got a throughput bottleneck in there somewhere,
but I'm clueless as to where it could be:
   o disk?
   o disk controller?
   o the OSS driver?
   o PCI bus?
   o IRQ's?
   o the sound card's internal buffer
     (M-Audio denies this)?
   o memory buffers in linux?

And on the same note, if I could -detect- when a
recording hiccup has happened, that could let me dodge
the problem too.

I'm putting this out there to see if anyone can give
me some hints as to what my issues could be. The
M-Audio people insist that I should be able to do 16
stereo channels at the same time with no problem.. in
WINDOWS! Green with envy I be!

Any and all comments are amply welcomed. If you have
some tapes you'd like converted to CD, then by all
means let me know and I'll do them for free.

Thanks in advance,

--Craig Meyer
  Customer Service

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