Tivo Inc.'s eponymously named Tivo Personal video receiver is a consumer video component allowing users to capture television programming to internal hard drive storage. Tivo systems function similarly to VCRs, but use non-removable hard-disk storage, and generally contain more intelligence.
Tivos allow a user to specify programming to record by time, program name, or even more complex parameters. Utilizing an internal programming guide (updated nightly via phone connection to Tivo headquarters), the Tivo selects and records the desired programming. Programming may be stored until the large internal hard disk is filled to capacity, at which time Tivo must dispose of older programs. This practice of automatically recording programs for later viewing is often referred to as Time shifting.
In addition to recording specific programs, the Tivo unit constantly records the incoming television signal, allowing users to pause or rewind "live" TV within a short (generally 30 minute) buffer.
The Tivo unit was designed by Tivo Inc., which currently provides the Linux-based Tivo software and operates the subscription dial-up service (without which a late-model Tivo will not operate.) Tivo units are manufactured by various OEMs, including Philips and Sony, which license the software from Tivo Inc.
Tivo systems are based on PowerPC processors, connected to MPEG-2 encoder/decoder chips and high-capacity IDE hard drives. A typical Tivo unit can support up to two drives of varying capacity. Some Tivo systems are integrated with DirecTV receivers.
Some users are concerned about Tivo's ability to collect usage data from units via the telephone line; Tivo stipulates that (currently) all usage data is aggregated by zip code. Recently, some have complained about Tivo's agressive remote software-update system, which has the capability to add and remove features without customer's specific authorization. Early Tivo units were marketed as being capable of functioning without a subscription to the Tivo service (although functionality would be markedly reduced.) Newer units are designed to be non-functional without a connection, and customers who have had their older units remotely updated complain that Tivo is retroactively violating their promise.
Various groups exist to "hack" the Tivo box. Tivo has generally remained on good terms with these projects, although it has lately begun to clamp down on many of the "back doors" in the software.