How to Get Surround Sound

[tokteacher]

I am sure this has been asked before, but I could not find an answer.  I have downloaded numerous large video files that are labled as AC3, DTS, etc--that claim to have encoded surround sound.  When I transcode them for Apple TV Gen 3, they seem to all be 2 channel rather than multichannel. It seems that I have two problems:

1. Vuze is not encoding the video in 5.1, but downmixing to 2 channels--how can I get multichannel
   
2. I realize that I have been using Airplay and Homesharing, and these are probably 2 channel-any way to get a video on my PC to stream to an apple TV?
   

Thanks in advance for any help

Can anyone tell me how to