Subject: Re: [ecasound] Simultaneously recording many tracks
From: Eric Dantan Rzewnicki (eric_AT_zhevny.com)
Date: Wed Jun 09 2004 - 04:55:49 EEST
Some things to try if you haven't already:
ALSA drivers
Jackd
lowlatency/preemptive kernel configuration
tuning disks with hdparm or in your kernel config
test disks with hdparm
turn off anything else running on the box that is not essential
(hardware and software)
make sure your soundcard(s) is on the highest priority possible IRQs
typically this means IRQ 9
make sure your soundcard(s) is not sharing IRQ's with any other devices
google for linux audio users guide
read the archives of linux audio users and linux audio developers
mailinglists
join those lists and ask there
You should definitely be able to get the performance you're after. This
list is pretty low volume. You'll find much more activity on the lau and
lad lists.
hope this helps, and good luck. :)
-Eric Rz.
Cassettes2CDs wrote:
> 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
> important.
>
> 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?
> etc.
>
> 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
> Cassettes2CDs.com
>
> --
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