The Xbox One will not support Dolby Digital 5.1 surround sound via its optical out port at launch.
Optical out is the red fiber-optic port most commonly used by surround sound home cinemas or headphone systems for true 5.1-channel audio. At launch, Xbox One’s optical port will only output stereo sound.
Microsoft director of product planning Albert Penello confirmed via a post onNeoGAF, “Dolby Digital is coming post launch.”
He went on, “This was a [software] scheduling issue pure and simple, and I know people are disappointed, but we will have it.