Multiple output devices under CoreAudio with Quicktime
Multiple output devices under CoreAudio with Quicktime
- Subject: Multiple output devices under CoreAudio with Quicktime
- From: Dave Addey <email@hidden>
- Date: Mon, 14 Apr 2003 09:46:12 +0100
Hi,
I'm just about to start porting some Carbon Audio code to take advantage of
CoreAudio, and I'm really struggling to get a grip on the best approach to
take... Any help much appreciated! Questions below, after a brief
explanation:
I've written a Mac DJ application called DJ-1800 (see
http://www.dj1800.com/) using REALbasic. It allows multiple output devices
for DJing, and emulates 4 DJ-style "CD players" for controlling MP3
playback.
I'm currently working with a QuickTime movieplayer, which contains a movie
with 3 MP3 tracks (all identical). I'm using MediaSetSoundOutputComponent
from the Quicktime API to assign a different output device to each channel.
(This allows my DJ application to play a song through a master device and a
cue device at the same time).
Via Quicktime, I'm looking for all OutputComponents of type 'sdev', but on
OS X there are only the two - Mac OS Audio HAL, and Mac OS Audio HAL
(system) - corresponding to the system out and the system alerts out
respectively. I'm using these two to allow users to use two audio devices
(typical their built-in device, and an iMic or similar) - one for
headphones, and one for master oputput.
This works to a point, on OS 9 and X using Quicktime. However, I have two
major problems:
1) Users would like to be able to use more than two devices (e.g. an M-Audio
Delta 1010lt soundcard (with 8 outputs)) to assign four different output
devices (one to each CD player) - not possible with the current approach. I
believe I need to use CoreAudio to access these extra "devices" under Mac OS
X. How can I find all available output devices under CoreAudio, and assign
them to the tracks of a QuickTime movie?
2) Ideally, I want to be able to assign multiple output devices to one track
in a QT movie, rather than the clunky multi-track approach I'm having to use
currently. Is this possible under CoreAudio?
As I say, any help much appreciated...
Thanks,
Dave.
------------------------------------
Dave Addey
email@hidden
DJ-1800
Complete MP3 DJ solution for the Mac
http://www.dj1800.com/
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