[nas] synchronized or redirectable remote audio?

[Jon Trulson]

On Mon, 5 Nov 2001, Paul Fox wrote:

> Date: Mon, 05 Nov 2001 16:29:42 -0500
> From: Paul Fox <pgf at foxharp.boston.ma.us>
> To: nas at radscan.com
> Subject: [nas] synchronized or redirectable remote audio?
> 
>  
> i've been setting up a simple (?) home audio system based loosely on
> the capabilities of mpg123 (w/ nas support) and nas.
> 
> this system lets me, from a web page, direct an mp3 stream to the
> soundcard connected to one of several diskless systems around the
> house.  one of these is connected to the livingroom stereo, and it
> obviously gets the most exercise, but there are others in the kitchen
> and study that i use less frequently.
> 
> one of the things i naively tried was to use an mp3 rebroadcaster
> (icecast) to send the same stream to several destinations at once,
> thinking i'd get the equivalent of "remote speakers", and be able to
> listen to the same music all over the house.  silly me.  buffering and
> propagation delays make this completely unusable -- with a single
> source going to icecast, and being picked up by a couple of mpg123
> processes, and sent to two remote nas servers, i had a delay between
> the systems of well over a second -- this was not a subtle "delay"
> effect by any means.  :-)
> 
> so:  has anyone ever heard of any work done on synchronized remote
> audio?  i'm thinking of some sort of lightweight protocol among the
> clients that keeps them in sync during playback.
> 
> i fully expect that question to be answered with deafening silence. 
> :-)
> 

	[sound of crickets chirping on a quiet night] ;-)

	That question has been asked before, without any resolution of
course.  One thing that occurred to me would be to hack up the equivalent
of the X11 XSYNC extension into NAS which might be adequate.  Of course,
the ability to add extensions to NAS has long been on my 'dream' list...

> so, let's try for something maybe more tractable.  as a fallback, i'd
> like to be able to move the audio stream from (single) room to
> (single) room.  if, for example, i'm listening to music in the living
> room, and decide to go to the kitchen to make dinner, i'd like to be
> able to tell the mpg123 process that AUDIOSERVER has changed, on the
> fly, and that music should now go to a new destination, preferable
> fairly seamlessly.  clearly there's a bunch of closing/re-opening that
> has to happen, and i suspect the nas api's aren't capable of doing
> something like this.  anyone have any thoughts on clever ways to do
> this with existing tools, or not-too-extensive changes to nas client
> library internals that could make it possible?
> 

	Well, audiooss does something like this when it needs to reset
it's settings - it closes the current nas connection and reopens a new one
with the new parameters.  I'm not sure this is something that should be
handled by libaudio, since it can be easily done by the client.

	It almost sounds like that what you need would be some sort of nas
proxy client that could A) handle opening and closing connections to
multiple servers, and B) providing some simple synchonization between
them.  ie:  You use 1 mpg123 client to send data to the nas proxy, then
that proxy sends the data to one or more nas servers.  If there was a SYNC
protocol extension in NAS, then your proxy could also deal with keeping
the streams synchronized more precisely...


-- 
Jon Trulson    mailto:jon at radscan.com
ID: 1A9A2B09, FP: C23F328A721264E7 B6188192EC733962
PGP keys at http://radscan.com/~jon/PGPKeys.txt
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