Automatically switch audio output between 2.0 and 5.1

[AdamJensen]

I hook up my macbook air to the receiver (Harman Kardon avr265) to watch movies on my home theatre which has a 5.1 audio setup. I have selected encoded output so for the formats that the receiver supports VLC sends an encoded audio stream via HDMI which works great.

For audio formats which the reciever does not support it gets sent as PCM to the receiver and to get the best out of my set up I need to switch OSX sound output to 6 channels if the video I'm watching has 5.1 sound. Similarly I need to switch OSX sound output to 2 channels if the video I'm watching has 2 channels, so that the receiver's nice conversion to 5.1 can be utilized.

Is there a way to automatically switch OSX sound output between 6 channels and stereo depending on the number of channels in the audio stream that is being played? Or is there another solution?

[mac_man_ad]

Can your receiver not be set to convert to 5.1 anyway? My Marantz can be set to assume the input is stereo and upconvert no matter what is actually coming in.

[AdamJensen]

No I don't see a way. How can the receiver know if its actually 5.1 with the other tracks silent or if its just stereo? If by some method you force it to assume the input is stereo and upconvert, then it will be ignoring any actually surround streams and instead try to upconvert from stereo which is silly when you have proper 5.1 input.

I'm wondering if I should create a custom vlc module that could do this, but I wish there were a simpler way.

[mac_man_ad]

I leave the OSX outputting as many channels as it wants (over HDMI - 7.1 i believe) and theres a button on my receiver remote to swap it between "Direct" (only output what it gets) and "Stereo" (with sub options for what to do - only out two, out front, out all). However, my receiver does appear to do a very good job of knowing what it incoming and often swaps itself. And always knows it AC3 or DTS is incoming, then it swaps to decode them itself. I guess different receivers do behave differently (my old box i had to swap manually), but in my experience the receiver should be easier to change than the mac.