Inconsistent black levels between Showtime HD and SD on Comcast
Comcast was running a special, and I subscribed to be able to watch the Showtime series Sleeper Cell, and in HD no less. The show looks spectacular in HD, but the ads for it and other Showtimes series that are played before and after it in SD (standard definition) look terrible.
I’ve calibrated the black level of my display by eye to the Showtime HD material (I don’t know of a way to get the motorola cable box/dvr to output suitable test patterns). When Showtime plays its ads in SD the black levels are much higher than those of the HD video. Maybe they’re broadcasting HD at 0 IRE and SD at the U.S. standard of 7.5 IRE? That’s a possible cause of the problem, although the difference looks much worse than that. The SD stuff just looks like foggy crud.
