So sometimes when I'm watching a show in HD it looks pixelated and to be frank, it looks like crap, especially when there is a lot of motion. I don't notice any rhyme or reason to it either. Some channels/shows look fine, but some look like garbage. Does TWC compress select HD channels/shows? I know other cable companies are doing it, and I'm just assuming this is what I'm seeing.
That makes sense. SDV is ostensibly a way to conserve bandwidth by feeding certain channels only when customers are tuned to them. It only works well if all of the SDV channels are relatively unpopular so that few of them are being watched at any one time. But that's not how TWC is using it. They've assigned many popular channels to SDV. I presume they could feed different channels down different branches, but if at least one customer on a branch is tuned to a particular channel most of the time, then that channel has to be fed to the branch most of the time, so making it an SDV channel serves no purpose other than to frustrate CableCARD users who don't have a tuning adapter. Which may be the point.
To be fair, TWC is pretty much limited to adding only new channels to SDV since the FCC got after them for moving existing channels there, thus denying them to CableCARD users. That may change as tuning adapters get more common, especially if they don't charge extra for them or jack up the price of the CableCARDs to cover them.
I suspect that the SDV bandwidth is getting depleted by the near-constant demand for the popular SDV channels and TWC's only recourse is to severely cut each channel's bitrate. One way to test this is to pick a channel like Starz that repeats its shows a lot and watch a movie with a lot of action during primetime and again at a less popular time such as 4:00 AM. If the early-morning feed is cleaner that would point to SDV overload as the cause.
A better way would be if a channel that's causing trouble could be recorded to a file on a PC. The file could then be examined with the free TSReader Lite program to learn the bitrate. Perhaps the recording could be made using a cable STB with a functional Firewire port, provided the computer can record directly from the port. I expect all of these channels are flagged as Record Once at best.