When the HDMI people (Silicon Image) set up the HDMI spec, they put down some ground rules. According to Section 6.6 of the HDMI 1.3 Specification document:
Black and white levels for video components shall be either “Full Range” or “Limited Range.” YCbCr components shall always be Limited Range while RGB components may be either Full Range or Limited Range. While using RGB, Limited Range shall be used for all video formats defined in CEA-861-D, with the exception of VGA (640x480) format, which requires Full Range.
ALL video stored on modern discs, be it DVD or Blu-ray, are stored as YCbCr with a range of 16-235
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I'll say it again: Blu-ray and HD DVD movie formats are limited to 8-bit 4:2:0 YCbCr.