I never have figured out how it would know the difference between music or a movie.
The 861v4 preset model is described here:
http://www.Meridian-audio.com/568/V4_presets_usage.pdfIn short, certain assumptions are made for direct (non-SmartLink) analogue, PCM, and bitstream inputs:
2-channel analogue inputs are always Music2.
2-channel PCM inputs are always Music2.
6-channel analogue inputs are always Music6.
2-channel bitstream inputs are always Movie2.
6-channel bitstream inputs are always Movie6.
From a Meridian DVD player with a multi-channel digital connection, the type of disc is taken into account as well as the encoding. The preset category is then transmitted to the processor via SmartLink:
2-channel from a CD is Music2.
2-channel from a DVD-A is Music2 (including DTS 2.0).
6-channel from a DVD-A is Music6 (including DTS 5.1).
2-channel from a DVD-V is Movie2 (including DTS 2.0).
6-channel from a DVD-V is Movie6 (including DTS 5.1).
I don't know if SmartLink distinguishes between the DVD-A and DVD-V parts of a DVD-A disc. Presumably, a Meridian DVD-A player knows what the disc is even if it has been told (for some bizarre reason) to read the DVD-V part. To me, it would make sense for anything coming off a DVD-A to be treated as Music.
Edit: I added this to the Wiki
http://www.meridianunplugged.com/wiki/index.php/861