Playing AAC multichannel (5.1 surround) audio stream on Apple TV
I have a tvOS app that receives AAC 5.1 audio stream over the network and I am using AudioToolbox to decode (mFormatID = kAudioFormatMPEGAAC) to 5.1 channels. But I only hear 2 channels (Stereo) outputs on my 5.1 surround system (which is connected to the TV using an Audio Optical cable).
I am not sure why PCM multi-channel is not outputting from AppleTV. Am I missing anything?