Wifi streaming local, live audio to powered speakers.

[phoenix710]

All: I have been researching wireless audio streaming for several months now. While I'm comfortable with designing and building new HW around wireless chipsets (such as the Nordic nRF2460), the WL-520GU approach definitely has the edge in simplicity and cost!

The reason for this post, however, is to ask about the feasibility of using this project for a different task.

Rather than using this project to listen to internet radio, I want to use it for the sound system in our church (for the main speakers, as well as for floor monitors). This means that our multichannel mixer would source the audio, then a sound card/sound cards would do the ADC, then a Linux system would do the realtime MP3 encoding and be the live stream server, drive a local wifi hotspot, which would then send it to WL-520GUs located in (powered/amp'd) speakers. I envision the need for two parallel systems: one would be dedicated to the stream to main speakers, and the other to stream to the floor monitors. (These must be different streams, since the mix for the mains and the mix for the floor monitors will be different in most cases.)

So, here are my questions:

1. What are the recommendations for the realtime MP3 encoder and server? From recent reading, I think that I need something like shoutcast or icecast as the server, but my knowledge of what I can do on Linux is very limited. (I've used Ubuntu for about 2 1/2 years, but I'm definitely not a Linux guru. I do know how to use apt-get to install, and have sometimes built apps on the box if needed.)

2. We need independent volume control on each stream. Do I get this for free via the ADC, or do I need something at the WL-520GU receiving end as well?

3. Do I actually need two parallel systems (main and monitor), or can both signals be mixed on the same wifi signal, but automatically split by the receiving WL-520GUs? (perhaps by IP or port address on the source and/or destination?)

4. Since I can control both ends of this system, do I really need MP3 or can FLAC/OGG be used instead? Are there any compelling reasons either way? If the latter, what needs to be installed on the router to accommodate it? (My understanding is that FLAC is lossless, so potentially this should produce better audio.)

It's very important to note that since this is a LIVE system, and therefore can't drop audio - EVER. Since, by design, this system has it's own dedicated wifi network, I hope that this will not be a problem with the proper configs. This requirement, though, is the deal-breaker, so if you have suggestions on how this can be assured or pitfalls to avoid, please let me know. (Note, there are two other wifi networks in the venue, but are unused at the time we'll be using our wifi. Is this a potential issue?)

Has anyone used this project for live audio that you've sourced?

FYI: acquiring the router was easy. I found it on Amazon for $34 dollars and received it in 4 days (standard delivery).

Thanks!

[gerben]

Shoutcast is not meant for real-time transmission. My guess would be that the system you describe would have a 1-2 second delay, which I guess is unacceptable. Also the delay between main speakers and floor monitors might be different. I think you could look into VoIP, as an alternative.

[phoenix710]

gerben: Thanks much for the info. Yes, any delay greater than about 30mS would render the system unusable. Thanks for identifying a true "show stopper" in the original design concept. Well, it's "back to the drawing board..."

[pasdesignal]

If you really want to use some kind of IP protocol to distribute these streama around your venue, you will need to be build something as good as the AXIA LiveWire system, which has a guaranteed total delay of <10mS throughout the network.

This system is quite affordable to purchase, but I note they have now released some HW cards which can be integrated into components or used for DIY stuff like your project.

Links;
http://www.axiaaudio.com/routers/default.htm

http://www.axiaaudio.com/news/pr/2011_L ... ipping.htm

I have had a little experience trying out this type of technology and was very impressed by the simplicity and flexibility of it. No affiliation to the company by the way! But I thought it might give you some ideas....