Hi giorgio and mike,
Thanks for the compliment
The diatonis albums that come with a DVD is actually a hybrid disc...
meaning it contains both DVD-Video and DVD-Audio zones.
Hybrid discs will play in either player, normal DVD player or a DVD-Audio player.
The player will choose the zone to play.
The DVD-Audio zone doesn't play video because the bandwidth of the DVD is dedicated for audio: PCM usually at 96kHz / 24-bit depth compressed using a lossless MLP encoder.
The DVD-Video zone uses either PCM 48kHz/16-bits, Dolby Digital, or DTS and has video.
I think Robert Rich Somnium is, as mike mentioned, a DVD-Video disc. The audio is PCM at 48kHz/16-bits. There is no or very little video, a black image is a single frame of video repeated. The entire disc could hold about 7 hours of music because there is no video.