I have a Sony Bravia HDTV, with DirecTV satellite service, and I've noticed many times dark colors either have crushed blacks, banding artifacts, or hue shifts. Is this a normal issue with the HDTV standards, or is my TV just weird, or is it something to do with DirecTV's decoding? I'm guessing it has something to do with color bit depth and the YCrCb color space. Anybody have any idea?
DirecTV carries hundreds of channels and has to squeeze them all on the feed to and from the "bird" (orbiting communication satellite). To do this, it uses lossy data compression, which transforms the image in a way that lets it discard information that it thinks you are least likely to notice. Unlike Netflix, which carries scripted programming produced days or weeks in advance, DirecTV also carries live sports, political talk shows, and entertainment industry awards. This means DirecTV can't fine-tune the compression days in advance and has to let the compression run on autopilot.
A bright scene might have 200 units from shadow to highlight. A dark scene might have only 40. A poorly tuned compressor might not recognize the dark scene as needing more information allocated to it. This produces banding in some dark scenes.
Super Famicom analogy: Imagine you have a sprite tool that decides whether to use 2bpp, 3bpp, or 4bpp for a particular set of background or sprite art. It can't always tell by itself that fine gradations are important. So it tries to guess how many colors are needed to adequately represent the shape and volume of the cels. And sometimes it guesses wrong. In the case of a game, where the artist has the opportunity to approve each cel, the guess can be corrected. But in the case of a live broadcast over Satellaview where the cels were only created minutes ago, that might not be so easy.
MP2 and MP4 deal really badly with dark colors when constrained by low bitrates. (Other video standards may too, I don't know)
Unfortunately, as the various TV providers try to cram in more content into the same bandwidth, this is one of the victims.