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Digital video recorder
A digital video recorder (DVR) or personal video recorder (PVR) is a device that records video in a digital format to a
disk drive or other memory medium within a device. The term includes stand-alone set-top boxes, portable media players
(PMP) and software for personal computers which enables video capture and playback to and from disk. Some consumer
electronic manufacturers have started to offer televisions with DVR hardware and software built in to the television
itself; LG was first to launch one in 2007. A digital camcorder combines a camera and a digital video recorder.
Also, mobile phones often have a camera as well as some digital video recording capability.
Hard-disk based DVRs
The two early consumer DVRs, ReplayTV and TiVo, were launched at the 1998 Consumer Electronics Show in Las Vegas.
Microsoft also demonstrated a unit with DVR capability but commercial availability of this software would have to wait
until the end of 1999 for full DVR features in Dish Network's DISHplayer receivers. TiVo shipped their first units on
March 31, 1999, and to this day the last Friday in March is celebrated as a company holiday known as 'Blue Moon'.
Although ReplayTV won the "Best of Show" award in the video category with Netscape co-founder Marc Andreessen
as an early investor and board member, it was TiVo that went on to much greater commercial success. While early
legal action by media companies forced ReplayTV to remove many features such as automatic commercial skip and the
sharing of recordings over the Internet, newer devices have steadily regained these functions while adding
complementary abilities, such as recording onto DVDs and programming and remote control facilities using PDAs,
networked PCs, and Web browsers. The label PVR has almost fallen completely into disuse in the US trade news media
(it is still use in the United Kingdom and South Africa) in favor of the more popular DVR descriptor. The name PVR
never really caught on, although its use has not entirely vanished. As of December 29, 2008, Armstrong Cable still
uses PVR terminology.
Hard-disk based DVRs make the "time shifting" feature (traditionally done by a VCR) much more convenient,
and also allow 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 of advertising. Most DVRs use the MPEG
format for compressing the digitized video signals. When there is recorded time left to be played it is often referred
to as "future credit" or "the power". Despite the yearnings of customers, one cannot purchase more "future credit"
from a service provider.
DVRs tied to a video service
At the 1999 CES, Dish Network demonstrated the hardware that would later have DVR capability with the
assistance of Microsoft software. Users would have to wait until June 1999 for simple time shifting capabilities
in the 7100, rebranded as the DISHPlayer satellite receiver, which also included WebTV Networks internet TV.
By the end of 1999 the Dishplayer had full DVR capabilities and within a year, over 200,000 units were sold.
In the UK, DVRs are often referred to as "plus boxes" (such as BSKYB's Sky+ and Virgin Media's V+ which integrates an HD
capability, and the subscription free Freesat+ and Freeview+). British Sky Broadcasting markets a popular combined EPG
and DVR as Sky+. TiVo launched a UK model in 2000, and while no longer on sale, the subscription service is still maintained.
South African based Africa Satellite TV beamer Multichoice recently launched their DVR which is available on their Dstv
platform. In addition to ReplayTV and TiVo, there are a number of other suppliers of digital terrestrial (DTT) DVRs,
including Thomson, Topfield, Fusion, Pace Micro Technology, Humax and AC Ryan Playon.
Many satellite, cable and IPTV companies are incorporating DVR functions into their set-top box, such as with DirecTiVo,
DISHPlayer/DishDVR, Scientific Atlanta Explorer 8xxx from Time Warner, Total Home DVR from AT&T U-verse, 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+. Astro introduced their DVR system, called Astro MAX, which was the first PVR in Malaysia.
Sadly, it was phased out two years after its introduction.
In the case of digital television, there is no encoding necessary in the DVR since the signal is already a digitally
encoded MPEG stream. The DVR simply stores the digital stream directly to disk. Having the broadcaster
involved with, and sometimes subsidizing, the design of the DVR can lead to features such as the ability to use
interactive TV on recorded shows, pre-loading of programs, or directly recording encrypted digital streams. It can,
however, also force the manufacturer to implement non-skippable advertisements and automatically-expiring recordings.
In the United States, the FCC has ruled that starting on July 1, 2007, consumers will be able to purchase a set-top
box from a third-party company, rather than being forced to purchase or rent the set-top box from their cable company.
This ruling only applies to "navigation devices," otherwise known as a cable television set-top box, and not to the security
functions that control the user’s access to the content of the cable operator.
The overall net effect on DVRs and related technology is unlikely to be substantial as standalone DVRs are currently
readily available on the open market.
Introduction of dual tuners
In 2003 many Satellite and Cable providers introduced dual-tuner DVRs. In the UK, BSkyB introduced their first PVR
Sky+ with dual tuner support in 2001. 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. The PVR manufactured by UEC (Durban, South Africa) and used by Multichoice has the ability to view two programs while recording a third using a triple tuner. With some machines, such as the Scientific Atlanta 8300DVB PVR, it is possible to view one program whilst recording two other programs according to the users preference.
Integrated LCD DVR
DVRs integrated into LCD displays also exist. These systems let the user to simplify the wiring and
installation, and they have to use only one device instead of two.
There are examples of security systems integrated into such DVRs, and thus they're capable of recording more input streams
in parallel. Such devices can also be used as disguised observation systems, displaying pictures or videos as typical store
VESA Compatible DVRs
VESA compatible DVR are designed small and light enough to mount to the back of an LCD monitor that has clear
access to VESA mounting holes (100x100mm). This allows users to use their own personal monitor to save on cost and space.
Software and hardware is available which can turn personal computers running Microsoft Windows, Linux, and Mac OS X
into DVRs, and is a popular option for home-theater PC (HTPC) enthusiasts.
The article is based on materials from matroska.org, wikipedia.org.