[Noisebridge-discuss] a networked sound system idea

travis+ml-noisebridge at subspacefield.org travis+ml-noisebridge at subspacefield.org
Mon Oct 11 18:05:19 UTC 2010


Joe went back to his home with two new NSS speakers.

"Check this out", he said to his roommate Simplicio, plugging them in.

"Those are speakers?  Why are you plugging them in?  Where are the
 speaker cables?" said Simplicio.

"I'm plugging them in because they each have an amplifier inside them.
 And that's the beauty of it; there's no speaker cables.  Audio gets to
 the speaker in digital form, so no analog loss, no expensive cables."

"But how does the audio get there?"

"Well, built into the cabinet is a WiFi antenna, but as you can see,
 there's an ethernet jack that I'm plugging in now."

"So... they get audio over the network?" said Simplicio.

"Right.  A central computer, like my Mythbuntu box driving the TV
 right now, can send it audio.  Wait a moment while I plug it into the
 ethernet and I'll show you."

He plugged it into the network, and ran a command on his Mythbuntu
box.  It scanned the LAN, noticed the speakers, and acquired their
profile.  This allowed the speakers to tell the computer about their
unique amplifier and speaker response curve.  This meant that if the
speaker was not smart enough to correct the input, the computer could
do it.  It also told the computer whether it was capable of processing
OGG, MP3, OGG/FLAC, or simple WAV formats.

"Now the computer has found the new speakers.  I tell the computer
 what role they play - left and right - based on their MAC address,
 which is printed on the top like a serial number.  And at this point,
 I could also tell them what the WPA2 keys were, so that I could disconnect
 them from the ethernet.  Of course, I'd have to scan again if that were
 the case, so that it'd acquire their new IP.  But if one were so inclined,
 one could also statically map them to IPs in the WiFi router."

"So what else can they do?"

"Well, there's no limit on the number of speakers in such a system.
 The web-based GUI here shows that I can drive multiple sets in multiple rooms
 independently, or have them all play the same music.  In theory, I could
 add additional software that allowed the music to follow me from room to
 room, but I don't have the location gear needed to do that yet.

 Also, the VOIP phone system hooks in, so when it rings, I hear a mild
 ring throughout the house.  Of course you can limit the ring to certain
 places, or for certain lines, if you have multiple numbers.  The tone
 can also be customized to tell me who is calling, or it can read it
 out via text to speech.

 Further, there's a generalized response center hooked into it.
 Let me show you..."

A mild "whoop" sound filled the room.

"That was me logging into my server.  I can also tell snort to send IDS
 alerts through the system."

Simplicio: "Wow.  Hey, don't response curves change over time?"

"Well yes, if you're worried about that, you can plug a microphone in,
 run it out in front of the speaker, and the system can recalibrate itself."

Simplicio: "Hmm, and so how does it all work on the network?"

"It's simple IP traffic; in theory, these speakers could be remote, and
 I could be sending sound to a remote office, for example.  Or my mail client,
 when it receives a new email from my boss to me, could ping me while I'm
 here."

Prior art:
http://hints.macworld.com/article.php?story=20060602065532384

Possible problems:
Time synchronization between speakers

Possible solutions
Crossover ethernet - no intermediate switches
NTP and local clock
Subnet-directed broadcasts

Challenges:
Can someone make a generic module which will plug together with
  any speaker and power amp combo?  Would be nice to have a box
  which is "portable".
Can it be done with an arduino?
-- 
I find your ideas intriguing and would like to subscribe to your newsletter.
My emails do not have attachments; it's a digital signature that your mail
program doesn't understand. | http://www.subspacefield.org/~travis/ 
If you are a spammer, please email john at subspacefield.org to get blacklisted.
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