Feeding live audio through USB port to airport express

[kenoli]

I have several wireless mikes feeding into a mixer that we use for large group meetings, normally hard wiring the output from the mixer into a PA system.

What I would like to be able to do is to feed the sound from the mikes into a USB port on my mac and then feed the audio stream out through a wireless router to an airport express so that I can feed the stream wirelessly to a pair of self powered speakers.

I have a piece of software called Airfoil installed which will take the output of any mac software and feed it to the network just as iTunes feeds sound files or internet streams to the network. An interesting result of the way Airfoil feeds the audio through the mac system is that the audio is delayed by severals seconds.

I can't find a really good piece of software that will take the USB input and simply feed it to output as an audio stream. What I can do is to send a recording stream from a piece of software I downloaded called REC to Airfoil, which then sends it out to the airport express network. The problem here is that the delay results in feedback between the speakers and the mike that causes a dying echo of each sound fed into the mike.

Is there a way to avoid the delay (which airfoil says is inherent in the Mac sound wiring) that causes my echo problem?

Does anyone know of any software that can help me do what I want to do?

Thanks,

--Kenoli

 

[SocialistFish]

ah, didn't see that you mentioned airfoil in my first read through...

that was the only option i could think of off the top of my head...

 

[kenoli]

Airfoil, etc.

Thanks for your reply. Yes, the delay is the issue. It is OK if you are just sending audio from a file, but real time audio means you speak something and hear it seconds later through the speakers. It also makes it impossible to send the output of a video stream to external speakers as the audio gets out of synch with the video. I think this is inherent in something at the systems level in the mac and would need some software solution to compensate for it.

--Kenoli

 

[ChrisA]

The delay is going to kill you if you route through a computer. THere is no way around some delay bacause networks use "packets" to move data, the data is sent a block at a time and you have to fill the block before it can be sent. In any network this happens multiple times.

"Everyone" that does this uses simple wireless mics. These work on UHF. The best ones use what they call "diversity receivers" this means dual receivers each with it's own antenna. This fixes the drop out problem.

 

[kenoli]

ChrisA -- I think I see what you are saying. We are using wireless mikes, which, as you say streams UHF/FM. This gets the sound to our mixer. I thought it would be elegant if we could feed our speakers, which have internal amplifiers, wirelessly, rather than running a cable all the way across the room.

Are you saying that there will necessarily be a delay with networking because of the delay involved in filling packets. Are packets so big that they take several seconds to fill (this is the kind of delay we are dealing with here)?

Thanks,

--Kenoli

 

[ChrisA]

ChrisA -- I think I see what you are saying. We are using wireless mikes, which, as you say streams UHF/FM. This gets the sound to our mixer. I thought it would be elegant if we could feed our speakers, which have internal amplifiers, wirelessly, rather than running a cable all the way across the room.

Are you saying that there will necessarily be a delay with networking because of the delay involved in filling packets. Are packets so big that they take several seconds to fill (this is the kind of delay we are dealing with here)?

Thanks,

--Kenoli

Several seconds would be totally horrible. Tens of milliseconds are annoying. To put this in perspective, sound travels at 1 millisecod per foot. After 70 to 100 feet it sounds like an Echo. It is hard to run audio through a computer and not have an echo effect.

But the same wireless UHF technology that sends sound from the mic to the mixer can send sound to the speakers.

Any of the big pro-audio retailers can set you up.

 

[kenoli]

I actually did look around on the internet for stuff and found some UHF transmitters and receivers that are not too pricey. More stuff to buy, more radio waves flying around the room. I can almost feel my cells vibrate. The good ole American way . . .

--Kenoli