Re: [LAD] alsa card order

On Wed, 2009-04-29 at 09:01 -0400, drew Roberts wrote:
> On Wednesday 29 April 2009 07:45:08 Simon Fielding wrote:
> > On Tue, 2009-04-28 at 21:22 -0400, drew Roberts wrote:
> > > > The naming system exists for a reason, i.e. to allow you to easily
> > > > identify devices without remembering any cryptic numbers. It also
> > > > allows you to change the name during runtime via sysfs in case you
> > > > want to fix them up.
> > > >
> > > > > 1. I *want* stable indices, and
> > > >
> > > > Why?
> > >
> > > Well, I don't care how I would do it so long as I can finally find a way
> > > to do it.
> > >
> > > I want to load up 1 box with 4 sound cards (preferably el cheapo USB
> > > cards) and hoot the outputs of 4 radios to the inputs of the cards. (I
> > > prefer identical cards if possible.) I want to tune each radio to a
> > > different station and record each 24x7. now I want the stations to record
> > > consistently.
> > >
> > > So far I have not run across a solution that didn't assume different
> > > cards. Any ideas anyone/
> > > all the best,
> >
> > As far as I am aware, the only way to do anything like this is with
> > udev. I don't have any spare sound cards in the office so I've done some
> > experimenting with 2 identical mice. Running the following command
> >
> > udevadm info -a -p $(udevadm info -q path -n /dev/input/mouse0)
> >
> > for each mouse (soundcard in your case) replacing mouse0 with mouse1,
> > mouse2 etc and comparing the results shows that the only way to uniquely
> > identify them is by the usb port number eg :-
> >
> > ATTRS{phys}="usb-0000:00:1d.0-1/input0"
> > and
> > ATTRS{phys}="usb-0000:00:1d.0-2/input0"
> >
> > Providing that your radio/soundcard/usb port triplets remain the same,
> > either by never unplugging them, or by labelling them so that the same
> > radio connects to the same soundcard connects to the same usb port every
> > time, you could use the above ATTRS to write udev rules
> > in /etc/udev/rules.d/ which will allow you to name your devices whatever
> > you wish eg :-
> >
> > /dev/radios/luxembourg /dev/radios/texasbigbeat etc.
> >
> > Caveat: I have never written a udev rule in my life so you may need to
> > do some research and testing of that yourself.
> >
> > Hope this is of at least some slight help and/or interest.
>
> Thanks, I have got to try this out... And remember to report back...
> >
> > Cheers,
> > Simon
>
>
> drew
>
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I've subsequently found this thread on alsa devel which may help

http://thread.gmane.org/gmane.linux.alsa.devel/44498

Cheers,
Simon
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Received on Wed Apr 29 20:15:01 2009