Comcast is rolling out an update to MPEG-4 compression in many markets, including Houston where I am located. It appears they are going to send out their HD content in MPEG-4. This is a more efficient codec, so this gives them the flexibility to add more HD content or improve picture quality.
If you have a TiVo, when they flip the switch your cable card won’t change, but if your TiVo can’t support MPEG-4 you won’t get HD channels.
If you have the TiVo Bolt or TiVo Roamio, you are compatible and you do not need to make any changes.
If you have a TiVo HD or TiVo HD XL and your TSN begins with 652 or 658, you are compatible.
If you have a TiVo Series 3, you will lose your HD channels. If you want to stay with TiVo, you need to either upgrade to a Bolt or Roamio. If you are affected by this, TiVo Customer Service will make you a deal on a Roamio. If you don’t want to stay with TiVo, you could always start leasing a DVR from Comcast to keep getting HD channels. Otherwise your box will only get standard def.
I’m a fan of owning my own equipment, but this points out that technology sometimes moves faster than what you own. If you’re going to buy a set top box, pick something current and not a refurb of a model that’s a few years old if you want to get the maximum life out of your investment.