What is DVR technology?

Digital video recorder
From Wikipedia, the free encyclopedia

A digital video recorder (DVR) (or personal video recorder (PVR)) is a device that records video without videotape to a hard drive-based digital storage medium. The term includes stand-alone set-top boxes and software for personal computers which enables video capture and playback to and from disk.

The first DVR was tested on July 8, 1965, when CBS explored the possibilities of instant freeze-frame and rewind for sporting event broadcasts. Ampex released the first commercial hard disk video recorder in 1967. The HS-100 recorded composite analog video onto a 14" diameter hard disk using FM modulation. It could store a maximum of only 30 seconds, but could record continuously, and play back 2x normal speed down to still frame. http://www.cedmagic.com/history/instant-replay-hs-100-deck.html http://www.sssm.com/editing/museum/ampex/hs100.html

In 1985, an employee of Honeywell’s Physical Sciences Center, David Rafner, first described a drive-based DVR designed for home TV recording, time-slipping, and commercial skipping. US Patent 4,972,396 [1] focused on a multi-channel design to allow simultaneous independent recording and playback. Broadly anticipating future DVR developments, it describes possible applications such as streaming compression, editing, captioning, multi-channel security monitoring, military sensor platforms, and remotely piloted vehicles.

[edit] Hard disk-based DVRs

The two early consumer DVRs, ReplayTV and TiVo, were launched at the 1999 Consumer Electronics Show in Las Vegas. Although ReplayTV won the "Best of Show" award in the video category, it was TiVo that went on to much greater commercial success. The devices have steadily developed complementary abilities, such as recording onto DVDs, commercial skip, sharing of recordings over the Internet, and programming and remote control facilities using PDAs, networked PCs, or Web browsers.

This makes the "time shifting" feature (traditionally done by a VCR) much more convenient, and also allows for "trick modes" such as pausing live TV, instant replay of interesting scenes, chasing playback where a recording can be viewed before it has been completed and skipping advertising. Most DVRs use the MPEG format for encoding analog video signals.

The two consumer DVR brands in the United States are the TiVo and DNNA's ReplayTV. In the UK TiVo has a small presence; Thomson, Topfield, Fusion, Pace and Humax also supply digital terrestrial (DTT) DVRs. BSkyB markets a popular combined EPG and DVR as Sky+. South African based Africa Satellite TV beamer Multichoice recently launched their PVR which is available on their Dstv platform.

Many satellite and cable companies are incorporating DVR functions into their set-top box, such as with DirecTiVo, DishPlayer/DishDVR, Scientific Atlanta Explorer 8xxx from Time Warner, Motorola 6xxx from Comcast, Moxi Media Center by Digeo (available through Charter, Adelphia, Sunflower, Bend Broadband, and soon Comcast and other cable companies), or Sky+. In this case there is no encoding necessary in the DVR, as the satellite signal is already a digitally encoded MPEG stream. The DVR simply stores the digital stream directly to disk. Having the broadcaster involved with (subsidizing) the design of the DVR—and directly recording encrypted digital streams—can lead to features such as the ability to use interactive TV on recorded shows, pre-loading of programs. It can, however, also force the manufacturer to implement non-skippable advertisements and automatically-expiring recordings.

[edit] Introduction of dual-tuners

In 2003 many Satellite and Cable providers introduced dual-tuner DVRs. These machines have two tuners within the same receiver to operate independently of one another. The main use for this feature is the capability to record a live program while watching another live program simultaneously or to record two programs at the same time while watching a previously recorded one. Some dual-tuner DVRs also have the ability to operate two separate television sets at the same time.

[edit] PCs