Subject: Re: [ecasound] multiple input sound recording
From: C.Lee Taylor (leet_AT_leenx.co.za)
Date: Sat Jun 07 2003 - 15:06:44 EEST
Hirendra Hindocha wrote:
>Hi,
>
Greetings ...
>We've been using ecasound to record audio from one audio source
>and now we're looking for a solution where we can record audio
>from multiple sources and write it to the hard disk . I saw
>recently on the list about Delta 1010 card and its use in Linux
>based systems. Being a novice in this area, can anyone point me
>to a list of multi input cards that work with Linux ?
>
Funny that somebody should ask this ask this today, I have been
working on a project that will require multi source recording. Our
current solution is to use multiple stero audio capture cards ( Off the
shelf sound cards ), then using ALSA, split the stero line into two
seperate channel inputs. Currently we have two sound cards for test,
but I beleive this shuld work for up to eight sounds cards, which should
give you sixteen mono channels. In my computer on my desk, I have one
on-board sound card, and five free PCI slots, which would mean I could
personelly test six device setup, which is 12 channels. Hoping to get
enough cards to test this. In all the docs I have read through, they all
warn about sync, xrun and latancy problems, but for what we will be
using it for, none of these are a problem.
>Is it possible for example to create a Linux based recording
>system that records from different audio inputs simultaneously ?
>If you have built one please share the info. If anyone can point
>me to other sources on the Net, so I can educate myself, please
>let me know.
>
I test last night, the ablity to record from the four channels
indepentantly to ogg, with each recording taking about 10% of my CPU
while in X, using an Athlon XP 2000+ with 256MB DDR RAM, which I think
is fine. ( Side note, I was also about to use ecasignalview at the same
time, which I have not been able to do before.
As for MultiChannel sound cards, that a look in the ALSA sound card
DB, and see what they have in there. I have seen a few people on this
list using a few differant ones. One of these cards, somebody in the
ALSA mail list used two of these 10Channel cards can worked a solution
to give them differant configurations that would be almost five 4channel
recorder. Again, through, there are alot of warnings about xruns (
which I don't really know what this means ), latancy problems ( which,
if I understand - means slow stop and start ) and sync problems, which I
think is got to do with all channels using the same clock source, but,
as I have said, this is not a problem with our project, but could be
with a pro mixer setup using Linux, but then it might be alot better to
use JACK.
I hope this helps.
Mailed
Lee
P.S. What an idot, I got so worked up, I did not give any details on how
I did it ...
Attched you will fine a copy of my around.conf, which splits the stero
channel input into to mono channel capture devices.
Following url describes the basics ...
http://alsa.opensrc.org/index.php?page=.asoundrc
Following url describes using Two cards as one, which with a little
google power, turn the other way around ...
http://alsa.opensrc.org/index.php?page=TwoCardsAsOne
You will need the following to setup Multiple cards in a system ...
http://alsa.opensrc.org/index.php?page=MultipleCards
Following url just plan tips for ALSA, which is good ...
http://alsa.opensrc.org/index.php?page=AlsaTips
Following url explains ALSA plugins, which I found too much for my
little grey matter ...
http://alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html
Following url gave me the basics to begin my little search ...
http://www.mail-archive.com/alsa-user_AT_lists.sourceforge.net/msg07437.html
And this gave me an explaination that made sense ...
http://www.mail-archive.com/alsa-devel_AT_lists.sourceforge.net/msg07207.html
Have fun ...
This archive was generated by hypermail 2b28 : Sat Jun 07 2003 - 15:00:34 EEST