Originally Posted by domino92024
They would have to replace a lot of STBs, and figure out how to do MPEG4 ClearQAM for existing TVs.
Well, the reason they would have to replace STBs is because they generally do not have MPEG-4 decoders in them (some MPEG-2 decoders have the ability to do both, but generally not anything but the most recent STBs will have those futured in).
I'm sure you probably realize that, but that is the same reason why Clear QAM at MPEG-4 in existing HDTVs will not ever work.
The best way for cable to migrate to MPEG-4 is probably to replace their STBs through attrition to STBs that can do both, which would be a many-year process, and even after transition to keep just the clear QAM channels on MPEG-2 for backward compatibility with current sets. Once 80% of STBs are MPEG-4-capable, then they could start to transition over all of the encrypted stuff.
It would seem that they could then fit up to 5 channels into a single QAM slot rather than 2 or 3 which gives them another 160 to 250% capacity. It would seem like other technologies than MPEG-4 might make more sense, but then many of them would also require a STB changeout, so maybe not.
Another significant obstacle is that the source signals are MPEG-2, so it would have be be somewhat of a coordinated change from the networks all the way to the STBs, otherwise they would have to convert incoming signals to MPEG-4 locally. Thats a lot of infrastructure. DBS only has to do it once, while cable would have to do it at each local MSO plant, that is unless they are big enough (Cox qualifies) to use some sort of "headend-in-the-sky" redistribution. Part of that will be taken care of eventually because DBS is also pushing for native MPEG-4 distribution from their networks, which are essentially the same networks cable uses.
I can tell you this, however; DirecTV has done such an unexpectedly marvelous job transitioning to MPEG-4 that no one, not even trained eyeballs, can seem to see the difference between original MPEG-2 and MPEG-2 converted to MPEG-4. And it really makes a difference in HDD space; I can get about 475 hours of HD on a 2 TB drive. The only real disadvantages are that channel acquisition times are a bit longer, and FFWD is choppy rather than smooth (faster decoders in DVRs may fix this in a year or two).