I'm trying to output 5 or more channels of mono audio to a receiver, but I want to play the same in the same room at different volume levels. I need to be able to control the volume of each channel independently and programmatically.

Imagine a single computer is hooked up to a 5 or 7 channel receiver in an open floor office and we want everybody to be able to hear the same music (in perfect sync). Since sync is an issue, something like Airplay isn't good and since we want nice speakers and have a single receiver, multi-cast wouldn't be ideal either.

When the phone rings in a certain area of the room, we'll have a script to lower the music volume in that portion of the room. However, we need a way to actually change the volume and drive all the channels. Right now, we just have a single volume level in the whole room but want many speakers all around the room so sound is more balanced.

  • What OS is running the music output? iOS/Mac/Windows? Physically what is a channel? If you have a budget for hardware or time to spend on this, it might help someone know what options to offer to you. Since a Mac can control an entire live music show - it's just a matter of software (ableton live and automation) and hardware (firewire/thunderbolt) and perhaps a midi controller to make the control easier than typing on a keyboard. – bmike Dec 30 '15 at 0:00
  • This is for OS X on a stock Mac Mini. Of course, given enough money I'm sure you can do many things. However given as little additional hardware as possible or none, what could I do from a Mini connected to a receiver that either takes 7 analog audio channels or coax / optical? I basically want Spotify to come out of 7 speakers - each with their own volume control. Then I need to be able to control the volume of each speaker from a script. – jon_wu Dec 30 '15 at 8:30

You could try using the Apple Audio MIDI Setup (found in the Utilities folder in most version of the Mac OS) to drive your sound levels differently. This will ONLY work if the Mac recognizes the output hardware as having discreet channels. Many audio receivers do not expose the discreet channels to your computer. That’s what the receiver is for.

If the receiver does expose the channels in a way the Mac can see then you should be able to set the volumes each independently with the Audio MIDI Setup.

You could also try to use Soundflower (16ch) and see if that will drive your receiver and/or speakers.

Here’s and example image showing Soundflower (16ch) configuration in the Apple Audio MIDI Setup interface. enter image description here

Also here’s a thread over on Apple’s support side about using AppleScript with the Audio MIDI Setup app: https://discussions.apple.com/thread/2582322?tstart=0

  • I tried this app earlier and you identified 2 issues I was having. 1) not getting more than 2 channels to show up. At the time I only had an analog output hooked up to my stock Mac Mini though. 2) controlling the GUI via AppleScript. That link definitely looks useful. Now, how do I get 5.1 or 7.1 to go out of the Mac over optical so the receiver gets all discrete channels? Maybe only 5.1 is possible according to m.reddit.com/r/hometheater/comments/3pslwi/… however, is it even possible to get OS X to create a 5.1+ channel DTS signal on the fly? – jon_wu Dec 30 '15 at 8:41
  • Yes, you can get 5.1 out of the Mac. I’ve done this for years. But, optical output won’t provide the connection you need (based on my previous audio work). What you need is an audio interface going out over Firewire, USB or Thunderbolt. The Mac works fine for this kind of thing, it’s all about the sending and receiving hardware. You will need high end audio equipment to pull this off. Also, for what you want to do 5.1 isn’t the right solution. You need desecrate speaker systems in each room or area. 5.1 was NOT designed for that, it’s meant for a single room. – kenjikato Dec 30 '15 at 9:55
  • Here’s a great link outlining some of the things you will need to think about when building out your audio interface. ehomerecordingstudio.com/best-audio-interfaces You should also look at getting a system designed for this like a Sonos. Here’s a quick example of multi area working with a Sonos. crutchfield.com/S-gUUtyD0y3rg/learn/… – kenjikato Dec 30 '15 at 10:04

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