I am working on this project where we are doing a live performance with about 6 musicians placed away from each other in a big space. The audience will be wearing their headphones and as they move around we want them to hear different kinds of effects in different areas of the place. For calculating the position of users we are using bluetooth beacons. We're expecting around a 100 users and we can't have a latency of more than 2 seconds.
Is such kind of a setup possible?
The current way we're thinking of implementing this is that we'll divide the place into about 30 different sections.
For the server we'll take the input from all the musicians and mix a different stream for every section and stream it on a local WLAN using the RTP protocol.
We'll have Android and iOS apps that will locate the users using Bluetooth beacons and switch the live streams accordingly.
Presonus Studio One music mixer - Can have multiple channels that can be output to devices. 30 channels.
Virtual Audio Cable - Used to create virtual devices that will get the output from the channels. 30 devices.
FFMpeg streaming - Used to create an RTP stream for each of the devices. 30 streams.
Is this a good idea? Are there other ways of doing this?
Any help will be appreciated.
First, you need to capture those six channels of audio into something you can use. I don't think your idea of virtual audio cables is sustainable. In my experience, once you get more than a few, they don't work so great. You need to be able to go from your mixer directly to what's doing the encoding for the stream, which means you need something like JACK audio.
There are two ways to do this. One is to use a digital mixer to create those 30 mixes for you, and send you the resulting stream. Another is to simply capture the 6 channels of audio and then do the mixing in software. Normally I think the flexibility of mixing externally is what you want, and typically I'd recommend the Behringer X32 series for you. I haven't tried it with JACK audio myself, but I've heard it can work and the price point is good. You can get just a rackmount package of it for cheap which has all the functionality without the surface for control (cheaper, and sufficient for what you need). However, the X32 only has 16 buses so you would need two of them to get the number of mixes you need. (You could get creative with the matrix mixes, but that only gets you 6 more, a total of 22.)
I think what you'll need to do is capture that audio and mix in software. You'll probably want to use Liquidsoap for this. It can programmatically mix audio streams pulled in via JACK, and create internet radio style streams on the output end.
You're going to need a server. There are plenty of RTP/RTSP servers available, but I'd recommend Icecast. It's going to be easier to setup and clients are more compatible. (Rather than making an app for example, you could easily play back these streams in HTML5 audio tags on a web page.) Liquidsoap can send streams directly to Icecast.
Keeping latency under 2 seconds is going to be a problem. You'll want to lower the buffers everywhere you can, particularly on your Icecast server. This is on the fringe of what is reasonably possible, so you'll want to test to ensure the latency meets your requirements.
100 clients on the same spectrum is also problematic. What you need depends on the specifics of your space, but you're right on the line of what you can get away with using regular consumer access points. Given your latency and bandwidth requirements, I'd recommend getting some commercial access points with built-in sector antennas and multiple radios. There are many manufacturers of such gear.
Best of luck with this unique project! Please post some photos of your setup once you've done it.