levision (3D-TV) will also require upgrades as subscribers purchase 3D-compatible televisions and as content in 3D becomes available. Improved compression and other techniques such as rate shaping provide the capability to carry additional video traffic. Rate shaping adds capacity by using a form of over-subscription. It's analogous to pouring one-and-a-quarter quarts of water into a pail that holds only a single quart. Rate shaping equipment discards bits in real time SO that adding eight megabits of traffic to a six-megabit channel does not impact quality. Supporting More Video by Converting to Digital Cable TV Competition from former telephone companies moving into their territories is driv- ing cable TV providers to focus on upgrading their infrastructure. This competition has resulted in lower prices and the drive to offer more channels of entertainment to match the offerings of their competitors. One way cable TV providers are gaining more capacity is by converting their infrastructure from analog to digital. Analog video requires an entire 6MHz channel for each movie or show. However, digital cable's increased capacity can transmit 10 to 12 channels of standard-definition video and two to four channels of HDTV or 3D video on each 6MHz channel. Standard-definition TV has lower resolution than high-definition television. Moreover, digital cable results in improved resolution because there is less interference from noise, which creates snow and shadows that appear on the television screen. Because of its higher capacity, cable providers such as RCN and Verizon have converted their entire infrastructure to digital. In areas where providers still transmit in both digital and analog formats, customers that sign up for the higher-priced digital cable pay an extra fee for premium channels only available in digital formats. A con- sumer can opt for set-top boxes with hard drives capable of storing content and playing it back at her convenience. Digital cable is also the basis for VOD. Nearly 100 percent of all cabl