10.4: Fun with Audio Units
May 02, '05 12:35:00PM
Contributed by: nevyn
You can do some mighty cool stuff with the new audio system in Tiger. Want to apply realtime AudioUnit effects such as reverb or pitch to your main sound out? Or perhaps you want to have quadrophonic sound by connecting two sound systems to your computer? Read on...
Here's how to play with real-time Audio Unit effects:
- Install the freeware Soundflower. You'll need this for virtual sound channels. It's a nifty tool; check it out even if you're not going to use it for this. Might require reboot to activate.
- Install Apple's Developer Tools. Even if you're not a developer, there's some real nifty stuff on there (Quartz Composer, etc.). What we want is the AU Lab application.
- Open up Audio Midi Setup (in /Applications/Utilities). In the Audio menu, go to Open Aggregate Device Editor. This lets you stuff audio streams together as if they were one single device. Create a new aggregate device, name it "Virtual + Built-in" or whatever. Put the Soundflower virtual device first (2ch or 16ch, doesn't matter), THEN the built-in audio (you can drag and drop). Don't forget to check the "Use" buttons!
- Click Done. Set the Default Output dropdown to the right to the new virtual device. Now you won't hear sound for a lil' while.
- Open up the nifty AU Lab tool over in /Developer/Applications/Audio. You'll now be wanting to create a new document. Use these settings:
- Audio Device: "Virtual + Built-in" (or whatever you named it).
- Outputs tab: Drag the red box to the two channels in Stream 2, these will be at the far right, either 17 and 18 or 3 and 4.
- Inputs tab: Click the "(+) Add Input" and drag that little red box to channel 1 and 2 in "Soundflower Input Stream #1". Click OK.
You should now be able to hear sound again.
- In the small green boxes with a "B" button before them in the Effects section, you can now add effects. I'll let you play with that on your own.
You could've done all this stuff with Audio Hijack Pro, too, but this way is more fun. To revert these settings, quit the Au Lab tool, and then just go to the Sound System Preferences panel, click the Output tab, and choose 'Built-in.' You can also remove Soundflower using the uninstaller on its disk image.
Read on for a 'bonus hint' to create "Quadrophonic" sound...
How to create Quadro-or-whatever-phonic sound ... so you're sitting there with both Built-in audio out and your shiny USB sound system. What a shame that you can't combine them to have four channels of sound. Or wait! You can! You might already have guessed how:
- Plug two speakers to the usual headphone jack on the computer.
- Plug two speakers to your USB/Firewire (an iVoice with stereo out or whatever)
- Open Audio Midi Setup
- Menu Audio: Open Aggregate Device Editor...
- Press the shiny "+" button (they're all shiny, aren't they?). Name the new aggregate device "I Can't Believe It's Not Surround!" or whatever.
- Put a box in "Use" for Built-in Audio and another box at the device corresponding to your USB device. (Checking Soundflower won't be much use, as those are virtual outputs, dummy...).
- Drag the device that you want as front speakers above the device that you want as rear speakers. Press Done.
- Properties For drop-down: Select your new aggregate device
- "Configure Speakers"-button
- Check all the checkboxes in the box at the top
- "Multichannel"
- "Stereo" dropdown
- choose "Quadrophonic"
- Click the buttons to make sure you get sound. Beware, the buttons are laggy. Don't click like a maniac.
- Press Apply and Done.
- Default Output: [name of your new aggregate device]
Congrats! You now got almost-surround. Go play some DVDs!
[robg adds: I tested the first part of this hint, but not the second. The first part worked well, and there are tons of settings to tweak for each Effects setting. Quite fun, if not entirely productive :) ]
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Mac OS X Hints
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