[pulseaudio-discuss] Controlling where module-rtp-send sends multicast packets?

Matthew Patterson matt at v8zman.com
Fri Feb 15 07:53:20 PST 2008

Ah, where to start:

Yes, the energy costs are part of my issue here. I just got through with 
building a hi efficiency core2 duo based machine that is my always on 
ubuntu server, so that was the reason I was trying to do it all on the 
PC. I figure I have plenty of extra processor cycles, and half the 
reason that machine is up is to store/stream my media content to other 
pc's in the house and my phone and work computers. Building this machine 
has saved me $28 a month on electricity, so you get the idea what sort 
of beast I had before :)

In order to keep the signals for each room as synced as possible I was 
going to do all the outputs (4 zones) by just getting a single high end 
7.1 audio card and using the remap module to create 4 stereo outputs, 
all on the same crystal to boot! From there I thought about running line 
level wires throughout the house, but don't want to pay for the high end 
balanced leads I would need to get quality, and the girlfriend wants as 
little intrusion into each room as possible. So I figured I would put a 
rack of amps right next to my pc, control them via 12v triggering/audio 
triggering (or maybe a pc controlled power switch), and run powered 
leads through the attic/crawlspace to all the rooms. For control I was 
going to buy a few touchscreen internet tablets like the noki 810's and 
place them in each room.

I already have a super simple web interface that allows my phone to 
stream my content down, so I figured I would expand it a little to make 
control of the various zones possible and more useable on a touchscreen 
device. In the meantime though I have written the python/php piece that 
allows me to select which zone connects to which music stream, and then 
I am running 4 instances of mpd which provide the playback for the zones.

As for why I am using multicast, it is because that seemed like the only 
way I could replicate streams to more than one sink. Please fill me in 
if I'm wrong since it seemed like a little overkill. I would before a 
simple copy stream module. This allows any single room to connect to any 
other room's currently playing audio on demand.

Your project looks awesome Jon! I am wondering what your BOM cost is for 
the end units that have both processing and amplification? Also, what 
are the specs on the audio codecs/dacs used in the boards, and what are 
the performance numbers on the amp units? I am a bit of an audiophile so 
stuff like that is important to me (although the girlfriend would never 
notice). I have been buying up NHT speakers and NAD/Carver amps for this 
project. Also, what sort of device/device synchronization accuracy are 
you getting? I was going to toss the outputs of my system on my scope 
and see just how good the syncing is, I'm just curious to see how the 
truly seperate device solution plays out.

So coming at this from another angle, since some of you are obviously 
going to be spewing multicast onto your networks and your routers don't 
complain, what make models do you guys have? All I need is the basic 4 
port 10/100 switch/wireless ap/firewall box.

The on PC firewall sounds interesting, and that is what I was going for 
by changing the kernel routing tables. I would prefer something more 
elegant though. I'm not afraid of the code either. If someone gives me a 
pointer to where to look in the code, where network device binding 
happens, etc. I might be able to add a parameter or something that 
allows device selection manually.


Jon Smirl wrote:
> On 2/15/08, Chris Ribe <chrisribe at gmail.com> wrote:
>>> You can also use x86 boxes but they are more expensive
>> Not if you already have them lying around :)  If I wanted to splurge on
>> dedicated hardware for whole house audio, there are already a number of
>> options out there.  The Sonos, Squeezebox, and Airport Express/Apple TV
>> (just to name a few)  are all pretty cheap and work wirelessly.
>> I'm more intrigued by the possibility of turning my dumpster bound PC
>> hardware into something useful using PulseAudio.
> Work out the electricity and AC costs and you won't think they are so cheap.
>> -chris
>> --
>> TV/IT Engineer
>> WCJB-TV Gainesville, FL
>> (352) 416 0648
>>  cribe at wcjb.com
>> _______________________________________________
>>  pulseaudio-discuss mailing list
>>  pulseaudio-discuss at mail.0pointer.de
>> https://tango.0pointer.de/mailman/listinfo/pulseaudio-discuss
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