[Xastir] Soundmodem

[Andrew Errington]

On Sat, 07 May 2011 22:53:57 Mark White wrote:
> On 5/7/2011 5:04 AM, Andrew Errington wrote:
> > Hi all,
> >
> > Where should soundmodem development/bugs be addressed to?
> >
> > I am trying to create two modems, one on each of two USB audio devices. 
> > I want one on /dev/soundmodem0 and one on /dev/soundmodem1.  I can
> > configure what I want with soundmodemconfig and it is recorded correctly
> > in /etc/ax25/soundmodem.conf, but when I run soundmodem only the first
> > listed device is created.
> >
> > I tried this with version 0.10 (packaged with my distro) and 0.15 (built
> > from source).
> >
> > Aside from that I'd also like to report that soundmodem -h doesn't work,
> > and it is also not obvious how to get a version number.
> >
> > 73,
> >
> > Andrew
> > _______________________________________________
> > Xastir mailing list
> > Xastir at lists.xastir.org
> > http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
>
> Andrew
>
> It's been a while since I've used soundmodem but I don't think there is
> an official list to report bugs.  It pretty much "just works".  A long,
> long time ago, I did some development related to soundmodem and mkiss
> but my memory is a little fogged so bare with me.
>
> Since the ax25 stack is integrated into the Linux networking stack,
> applications like xastir use the standard networking API to send and
> receive packets.  On the bottom, you need a driver to send the actual
> data to the device.  For soundmodem, that driver is mkiss.  But it
> doesn't actually 'drive' a real hardware device; it sets up one end of a
> PTY (can't remember if it's the master of slave end).  Soundmodem sets
> up the other end and encodes / decodes data between the PTY and sound
> card.  Pretty ingenious in that all the heavy lifting is done in user
> land as opposed to down in the kernel.
>
> So, I'm not sure what you're trying to do constitutes a bug.  Since
> you're trying to drive two sound cards, it would seem that you need two
> instances of soundmodem running.  Never tried doing that and I'm not
> sure if that is possible with mkiss.  If it works, note that all traffic
> from ax25 apps will go out both sound cards.
>
> Pretty much all I remember.
> Mark

That's excellent!  Thank you.  I see that I can create a number of 
configurations in the configuration file, but for each modem I must run an 
instance of soundmodem.  I can use the -c option to choose which of the two 
configurations should be used.

I'm actually using KISS not MKISS, but I get what you are saying.

It's late here, but I will try tomorrow.  I think I will be able to do what I 
want.

I never heard anything back from this list about running two modems on the 
left and right channels of the same audio device, and I haven't found 
anything while Googling.  I shall assume soundmodem was not written to allow 
this (AGWPE does do this).  The USB sound cards are so cheap that it's 
probably just as easy to have one modem per card and ignore the 'spare' 
output channel.  Most of them have mono inputs anyway.

Many thanks and 73!

Andrew