How to encode 2.1 source with CoreAudioToolbox?, Moderation: via qaac, currently giving error: unsupported audio format Options

[Anakunda]

HI! I need help to encode 2.1 audio with qaac. Passing it the source, I get an error: unsupported audio format.
Maybe there's a way to remap the channels to suit quicktime's scheme, or other workaround. Thankyou.

[nu774]

HI! I need help to encode 2.1 audio with qaac. Passing it the source, I get an error: unsupported audio format.
Maybe there's a way to remap the channels to suit quicktime's scheme, or other workaround. Thankyou.

qaac complains because 2.1ch is not available by AAC/ALAC encoder. As for qaac, you can use matrix mixer for downmixing to stereo (see usage page).
In this case, probably just dropping LFE channel is enough. so, you can use the following matrix:

CODE

1 0 0
0 1 0

If you are working with QuickTime pro, you can manually assign each channels, and specify output channel layout. If you are working with CoreAudio as a programmer, probably you have to implement mixer by yourself.