Live audio video broadcasting
This page describes the basic conditions how a set up should be build for an application similar to xmeeting or skype. This mainly concerns how to synchronize audio to video, and a way to prevent audio feedback.
Audio synchronize
Because the videocamera produces a stream of images with a slight delay (iSight with about 170 ms), the only possibility for audio to be in sync with the video is to delay it. This can be done completely with software, not requiring additional hardware.
Following software should be installed:
Follow these steps
Start JackPilot
Start AU lab (/Developer/Applications/Audio/), leave the 'Create New Document…' window as it is. This will come later.
Build an aggregate device
JackPilot→Menu: “Open Audio MIDI Setup…”
Audio→Menu→Open Aggregate Audio Device Editor→Merge Built-in Output and Built-in Onput into one device, Set clock to “Built-in Output”
Configure the audio input source. (Macbook Pro's line-in)
On the main Audio Tab→System settings, Default Input: JackRouter (This is where your audio source should refer to)
On the main Audio Tab→System settings, Default output: JackRouter (You can ignore this, the use of this is now not important)
In the small JackPilot window which shows the number of JackConnections and the CPU Load, click on Start. Then click on Routing
In Au Lab, set preferences, to output sound to the virtual Jack Audio rail
In Au Lab, create a new Document. For the delay-effect, you will only need to create one channel
Audio Device: JackRouter
Inputs→Add input→1
Output→1
in the Jack Connections Manager, create a stereo connection from line-in to Jack in
select in column 'Send Ports:' system, capture_1 and in column 'Receive Ports:' AU Lab, in1. Doubleclick on one of them, to establish a connection.
Repeat previous procedure for the other (Right) channel.
Audio Engine running?
JackPilot actively Routing?
Start the application which should receive the delayed audio (e.g. Skype or Quicktime)
Now route the Au Lab output to the application input
Bluetooth audio output