HD DVD
In the HD DVD format, Dolby TrueHD was a mandatory codec. The HD DVD specification permitted the sole (primary) audiotrack of a movie to be encoded in Dolby TrueHD, and the specification requires support for up to 2 channel (stereo) decoding. In practice all HD DVD players decoded multichannel (5.1) programming, and of the few HD DVD movies to be encoded with Dolby TrueHD audiotracks, all were multichannel.
The Phantom of the Opera, released April 18, 2006 on HD DVD, was the first movie to offer a Dolby TrueHD soundtrack.
Read more about this topic: Dolby True HD