There is actually some pretty good software that does this - it's just not very common because cable companies control the DVRs and they have to agree to rules

There is actually some pretty good software that does this - it's just not very common because cable companies control the DVRs and they have to agree to rules set by the networks. For example, the open sourice MythTV DVR does it. http://www.mythpvr.com/mythtv/taxonomy/term/4 http://www.mythpvr.com/mythtv/taxonomy/term/4