22 Nov
2008
22 Nov
'08
8:42 p.m.
Greetings,
I need to make a headless rackmount mixer/router with some basic processing
capabilities that will have eight line-level inputs and four outputs; it
should be configurable (in real time) for routing one or more inputs to
one or more outputs, with mixing and optional equalization of the sources
(up to eight equalizers). The platform will use commodity PCI sound cards
and due to the need to use available materials, will be based on an
industrial form factor 2u rackmount ASUS Socket-7 PC with an AMD K6/300 CPU
and 256 MB ram. Sample rates will be 44.1 or 48 kHz (stereo) 16bit max.
At some point, it should be controllable using an arbitrary protocol over
UDP, and of course should not require any sort of GUI. For development
I am willing to live with remote shell execution, or in the extreme,
an X-window on a controlling host.
I am willing to drive all the sound cards from a single master xtal oscillator.
What can ALSA/LADSPA and plugins with an absolute trivial LADSPA host together
with 'jack' do for me in this regard? Will I need to combine the sound cards
as a single virtual card and if so, will I have the flexibility to route and
mix as described above? Latency should be less than 10ms or so through any
channel route if possible. Should I instead consider running a 'jackd' per card?
Will I be able to switch an equalizer into any 'graph' that I construct to
permit shaping any input before mixing and output?
As you can see, I am trying to build a device that I am sure could be purchased
from someone like Roland, but 'on the cheap'.
All replies appreciated.
Michael
in this regard? W
22 Nov
22 Nov
9:08 p.m.
New subject: 8 channel mixer/equalizer implementation suggestions needed
Hi!
I'm no expert on this, but here's a bit of brick-or-brack I've worked
with.
You could use Fons Adriaensons filters.so as an EQ. It's a parametric EQ
with four bands in a LADSPA-plugin. Worked quite well for me.
Ecasound has a simple bypass-switch, which works in realtime. So I can
decide to use or to bypass all effects placed in a "chain".
You could use JACKD and somekind of audio-application to do versatile
routing. Of course the simple routing can be done with jack_connect and
jack_disconnect alone. But you need the LADSPA-host in between. I'd suggest
ecasound, because it's commandline only, but it has a lot of stuff built-in,
more than you'll need. But I suppose, if you want to write an ap for yourself,
you could do a LADSPA-host with a hardcoded max-input and max-output number.
the routing might be done using some jack_connect code on the outside or
inside your app.
About the soundcards and JACK: Best way would be to have one soundcard.
Second best, I GUESS, would be to have two, but only one JACK and sync the
cards via wordclock. You could use ALSA to build a virtual device, at least
I've heard of it being done.
I hope generic and inprecise as it is, it might help.
Kindest regards
Julien
--------
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======== FIND MY WEB-PROJECT AT: ========
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======= AND MY PERSONAL PAGES AT: =======
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23 Nov
23 Nov
4:22 p.m.
New subject: 8 channel mixer/equalizer implementation suggestions needed
On Sat, Nov 22, 2008 at 06:42:32PM -0600, Michael Grigoni wrote:
Greetings,
I need to make a headless rackmount mixer/router with some basic processing
capabilities that will have eight line-level inputs and four outputs; it
should be configurable (in real time) for routing one or more inputs to
one or more outputs, with mixing and optional equalization of the sources
(up to eight equalizers).
Note that with Jack, you can add and remove clients while the
transport is running.
Ecasound is a single project that provides many of the
routing abilities you seem to be wanting using an abstraction
called 'chains', and can do it with or without Jack. As
Julian writes, you can bypass chain operators and mute
chains in realtime. You can add/remove LADSPA effects in
realtime if you can tolerate a "glitch". Note that the routing
(chain setup) cannot be changed with the engine running.
There are interfaces to LISP, Perl and Python and C.
You may also also be interested in routing abstractions or
other code I have written as part of a perl module extension
for Ecasound, Audio::Ecasound::Multitrack, that includes a
recorder-mixer application.
Hope this helps,
--
Joel Roth
5894
days inactive
5895
days old
linux-audio-user@lists.linuxaudio.org
2 comments
3 participants
participants (3)
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bolangi＠nic-nac-project.org -
Julien Claassen -
Michael Grigoni