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A digital video recorder (DVR) is an
electronic device The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
that records video in a digital format to a
disk drive Disk storage (also sometimes called drive storage) is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is ...
,
USB flash drive Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply ( interfacing) between computers, peripherals and other computers. A bro ...
, SD
memory card A memory card is an electronic data storage device used for storing digital information, typically using flash memory. These are commonly used in digital portable electronic devices. They allow adding memory to such devices using a card in a so ...
,
SSD A solid-state drive (SSD) is a solid-state storage device that uses integrated circuit assemblies to store data persistently, typically using flash memory, and functioning as secondary storage in the hierarchy of computer storage. It is a ...
or other local or networked
mass storage In computing, mass storage refers to the storage of large amounts of data in a persisting and machine-readable fashion. In general, the term is used as large in relation to contemporaneous hard disk drives, but it has been used large in relati ...
device. The term includes
set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of s ...
es with
direct to disk recording A hard disk recorder (HDR) is a system that uses a high-capacity hard disk to record digital audio or digital video. Hard disk recording systems represent an alternative to reel-to-reel audio tape recording and video tape recorders, and provide n ...
,
portable media player A portable media player (PMP) (also including the related digital audio player (DAP)) is a portable consumer electronics device capable of storing and playing digital media such as audio, images, and video files. The data is typically stored o ...
s and TV gateways with recording capability, and digital
camcorder A camcorder is a self-contained portable electronic device with video and recording as its primary function. It is typically equipped with an articulating screen mounted on the left side, a belt to facilitate holding on the right side, hot-sw ...
s.
Personal computers A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...
are often connected to video capture devices and used as DVRs; in such cases the
application software Application may refer to: Mathematics and computing * Application software, computer software designed to help the user to perform specific tasks ** Application layer, an abstraction layer that specifies protocols and interface methods used in a ...
used to record video is an integral part of the DVR. Many DVRs are classified as consumer electronic devices; such devices may alternatively be referred to as personal video recorders (PVRs), particularly in Canada. Similar small devices with built-in (~5 inch diagonal) displays and SSD support may be used for professional film or video production, as these recorders often do not have the limitations that built-in recorders in cameras have, offering wider codec support, the removal of recording time limitations and higher bitrates.


History


Hard-disk-based digital video recorders

The first working DVR prototype was developed in 1998 at Stanford University Computer Science department. The DVR design was a chapter of Edward Y. Chang's PhD dissertation, supervised by Professors
Hector Garcia-Molina In Greek mythology, Hector (; grc, Ἕκτωρ, Hektōr, label=none, ) is a character in Homer's Iliad. He was a Trojan prince and the greatest warrior for Troy during the Trojan War. Hector led the Trojans and their allies in the defense o ...
and Jennifer Widom. Two design papers were published 2017 VLDB conference, and 1999 ICDE conference. The prototype was developed in 1998 at Prof.
Pat Hanrahan Patrick M. Hanrahan (born 1954) is an American computer graphics researcher, the Canon USA Professor of Computer Science and Electrical Engineering in the Computer Graphics Laboratory at Stanford University. His research focuses on rendering ...
's CS488 class: Experiments in Digital Television, and the prototype was demoed to industrial partners including SONY, Intel, and Apple. Consumer digital video recorders
ReplayTV ReplayTV was a former DVR company that from 1999 until 2005, produced a brand of digital video recorders (DVR), a term synonymous with ''personal video recorder'' (PVR). It is a consumer video device which allows users to capture television progr ...
and TiVo were launched at the 1999
Consumer Electronics Show CES (; formerly an initialism for Consumer Electronics Show) is an annual trade show organized by the Consumer Technology Association (CTA). Held in January at the Las Vegas Convention Center in Winchester, Nevada, United States, the event t ...
in
Las Vegas, Nevada Las Vegas (; Spanish for "The Meadows"), often known simply as Vegas, is the 25th-most populous city in the United States, the most populous city in the state of Nevada, and the county seat of Clark County. The city anchors the Las Vega ...
. Microsoft also demonstrated a unit with DVR capability, but this did not become available until the end of 1999 for full DVR features in Dish Network's DISHplayer receivers. TiVo shipped their first units on March 31, 1999. ReplayTV won the "Best of Show" award in the video category with
Netscape Netscape Communications Corporation (originally Mosaic Communications Corporation) was an American independent computer services company with headquarters in Mountain View, California and then Dulles, Virginia. Its Netscape web browser was on ...
co-founder
Marc Andreessen Marc Lowell Andreessen ( ; born July 9, 1971) is an American entrepreneur, investor, and software engineer. He is the co-author of Mosaic, the first widely used web browser; co-founder of Netscape; and co-founder and general partner of Silico ...
as an early investor and board member, but TiVo was more successful commercially. ''
Ad Age ''Ad Age'' (known as ''Advertising Age'' until 2017) is a global media brand that publishes news, analysis, and data on marketing and media. Its namesake magazine was started as a broadsheet newspaper in Chicago in 1930. ''Ad Age'' appears in mul ...
'' cited
Forrester Research Forrester is a research and advisory company that offers a variety of services including research, consulting, and events. Forrester has nine North America locations: Cambridge, Massachusetts; New York, New York; San Francisco, California; McLe ...
as saying that market penetration by the end of 1999 was "less than 100,000." Legal action by media companies forced ReplayTV to remove many features such as automatic commercial skip and the sharing of recordings over the Internet, but 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. In contrast to VCRs, hard-disk based digital video recorders make " time shifting" more convenient and also allow for functions such as pausing live TV, instant replay, chasing playback (viewing a recording before it has been completed) and skipping over
advertising Advertising is the practice and techniques employed to bring attention to a product or service. Advertising aims to put a product or service in the spotlight in hopes of drawing it attention from consumers. It is typically used to promote a ...
during playback. Many DVRs use the
MPEG The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by ISO and IEC that sets standards for media coding, including compression coding of audio, video, graphics, and genomic data; and transmission and f ...
format for compressing the digital video. Video recording capabilities have become an essential part of the modern
set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of s ...
, as TV viewers have wanted to take control of their viewing experiences. As consumers have been able to converge increasing amounts of video content on their set-tops, delivered by traditional '
broadcast Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...
' cable,
satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...
and terrestrial as well as IP networks, the ability to capture programming and view it whenever they want has become a must-have function for many consumers.


Digital video recorders 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. 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, digital video recorders 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+). Freeview+ have been around in the UK since the late 2000s, although the platform's first DVR, the Pace Twin, dates to 2002. British Sky Broadcasting marketed a popular combined receiver and DVR as Sky+, now replaced by the
Sky Q Sky Q is a subscription-based television and entertainment service operated by British satellite television provider Sky, as a part of its operations in Austria and Germany, Ireland, Italy and in the UK. The name also refers to the Sky Q set- ...
box. TiVo launched a UK model in 2000, and is no longer supported, except for third party services, and the continuation of TiVo through
Virgin Media Virgin Media is a British telecommunications company which provides telephone, television and internet services in the United Kingdom. Its headquarters are at Green Park in Reading, England. It is owned by Virgin Media O2, a 50:50 joint ventu ...
in 2010. 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
Technicolor SA Vantiva SA, formerly Technicolor SA, Thomson SARL, and Thomson Multimedia, is a French multinational corporation that provides creative services and technology products for the communication, media and entertainment industries. Vantiva's headq ...
,
Topfield Established in South Korea in 1998, TOPFIELD Co., Ltd. is a consumer electronics manufacturer making broadcasting receivers, other video and audio related apparatus. Their main business is making products such as set top boxes (STBs) and persona ...
, Fusion, Commscope,
Humax Humax (휴맥스) is a consumer electronics company. Founded in South Korea in 1989, it manufactures set-top boxes, digital video recorders and other consumer electronics. It is publicly traded on KOSDAQ. Listed on the Korean stock exchange ( ...
, VBox Communications, AC Ryan Playon and
Advanced Digital Broadcast Advanced Digital Broadcast (ADB) is a company which provides software, system and services to pay-TV and telecommunication operators, content distributors and property owners around the world. The company specializes also in the development of dig ...
(ADB). Many satellite, cable and
IPTV Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded med ...
companies are incorporating digital video recording functions into their
set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of s ...
, such as with
DirecTiVo TiVo digital video recorders encompass a number of digital video recorder (DVR) models that TiVo Corporation designed. Features may vary, but a common feature is that all of the units listed here require TiVo service and use its operating system. ...
, DISHPlayer/DishDVR, Scientific Atlanta Explorer 8xxx from Time Warner, Total Home DVR from AT&T U-verse, Motorola DCT6412 from Comcast and others, Moxi Media Center by Digeo (available through Charter, Adelphia, Sunflower, Bend Broadband, and soon Comcast and other cable companies), or Sky+.
Astro Astro may refer to: Entertainment and media * Astro (South Korean band), a South Korean boy band * Astro (UB40) (1957–2021), member of the British reggae band UB40 * Astro (Chilean band), a Chilean indie rock band * Astro (Japanese band), ...
introduced their DVR system, called
Astro MAX Astro MAX was a personal video recorder (PVR) service for Astro launched in July 2006. It marked the first PVR system ever to be introduced in Malaysia, though LG's PVR-integrated Time Machine TV introduced later that year. Its successor is th ...
, which was the first PVR in Malaysia but 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 digital video recorder 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 digital video recorders and related technology is unlikely to be substantial as standalone DVRs are currently readily available on the open market. In Europe
Free-To-Air Free-to-air (FTA) services are television (TV) and radio services broadcast in unencrypted form, allowing any person with the appropriate receiving equipment to receive the signal and view or listen to the content without requiring a subscripti ...
and
Pay TV Pay television, also known as subscription television, premium television or, when referring to an individual service, a premium channel, refers to subscription-based television services, usually provided by multichannel television providers, b ...
TV gateways with multiple tuners have whole house recording capabilities allowing recording of TV programs to Network Attached Storage or attached USB storage, recorded programs are then shared across the home network to
tablet Tablet may refer to: Medicine * Tablet (pharmacy), a mixture of pharmacological substances pressed into a small cake or bar, colloquially called a "pill" Computing * Tablet computer, a mobile computer that is primarily operated by touching the ...
,
smartphone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whi ...
, PC, Mac, Smart TV.


Introduction of dual tuners

In 2003 many Satellite and Cable providers introduced dual-tuner digital video recorders. In the UK,
BSkyB Sky UK Limited is a British broadcaster and telecommunications company that provides television and broadband Internet services, fixed line and mobile telephone services to consumers and businesses in the United Kingdom. It is a subsidiary of ...
introduced their first PVR Sky+ with dual tuner support in 2001. These machines have two independent tuners within the same receiver. 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, possibly while watching a previously recorded one. Kogan.com introduced a dual-tuner PVR in the Australian market allowing free-to-air television to be recorded on a removable hard drive. Some dual-tuner DVRs also have the ability to output to two separate television sets at the same time. The PVR manufactured by UEC (
Durban Durban ( ) ( zu, eThekwini, from meaning 'the port' also called zu, eZibubulungwini for the mountain range that terminates in the area), nicknamed ''Durbs'',Ishani ChettyCity nicknames in SA and across the worldArticle on ''news24.com'' from ...
, South Africa) and used by
Multichoice MultiChoice is a South African company that operates DStv, a major satellite television service in Sub-Saharan Africa and GOtv, a minor service operating in over 9 countries of this area and Showmax service. MultiChoice was formed out of the s ...
and
Scientific Atlanta Scientific Atlanta, Inc. was a Georgia, United States-based manufacturer of cable television, telecommunications, and broadband equipment. Scientific Atlanta was founded in 1951 by a group of engineers from the Georgia Institute of Technology, a ...
8300DVB PVR have the ability to view two programs while recording a third using a triple tuner. Where several
digital subchannel In broadcasting, digital subchannels are a method of transmitting more than one independent program stream simultaneously from the same digital radio or television station on the same radio frequency channel. This is done by using data compres ...
s are transmitted on a single RF channel, some PVRs can record two channels and view a third, so long as all three subchannels are on two channels (or one). In the United States, DVRs were used by 32 percent of all TV households in 2009, and 38 percent by 2010, with viewership among 18- to 40-year-olds 40 percent higher in homes that have them.Battaglio, Stephen. "Why the New Shows Aren't Working" ''
TV Guide TV Guide is an American digital media company that provides television program listings information as well as entertainment and television-related news. The company sold its print magazine division, TV Guide Magazine LLC, in 2008. Corporat ...
''; October 18, 2010; Pages 6–7


Types


Integrated television sets

DVRs are integrated into some
television set A television set or television receiver, more commonly called the television, TV, TV set, telly, tele, or tube, is a device that combines a tuner, display, and loudspeakers, for the purpose of viewing and hearing television broadcasts, or using ...
s (TVs). These systems simplify wiring and operation because they employ a single power cable, have no interconnected ports (e.g.,
HDMI High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controlle ...
), and share a common
remote control In electronics, a remote control (also known as a remote or clicker) is an electronic device used to operate another device from a distance, usually wirelessly. In consumer electronics, a remote control can be used to operate devices such ...
.


VESA compatibility

VESA VESA (), formally known as Video Electronics Standards Association, is an American technical standards organization for computer display standards. The organization was incorporated in California in July 1989To retrieve the information, searc ...
-compatible DVRs are designed to attach to the VESA mounting holes (100×100 mm) on the back of an LCD television set (TV), allowing users to combine the TV and DVR into an integrated unit.


Set-top boxes

''Over-the-air'' DVRs are standalone set-top-boxes that record broadcast television programs. Several companies have launched over-the-air DVR products for the consumer market over the past few years. Some pay-TV operators provide set-top boxes that allow subscribers to attach their own
network-attached storage Network-attached storage (NAS) is a file-level (as opposed to block-level storage) computer data storage server connected to a computer network providing data access to a heterogeneous group of clients. The term "NAS" can refer to both the tech ...
(NAS) hard drives or solid-state or flash memory to record video and other media files (e.g., audio and photos).


PC-based

Software and hardware are available which can turn personal computers running
Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...
,
Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...
, and
Mac OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lap ...
into DVRs, and is a popular option for home-theater PC (HTPC) enthusiasts.


Linux

There are many free and
open source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Open ...
DVR applications available for
Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...
. For example, TV gateway interfaces to DVB tuners and provides network tuner and TV server functions, which allows live viewing and recording over IP networks. Other examples include MythTV, Video Disk Recorder (VDR),
LinuxMCE LinuxMCE (Linux Media Center Edition) is a free and open source software platform with a 10-foot user interface designed to allow a computer to act as a home theater PC (HTPC) for the living-room TV, personal video recorder, and home automation ...
, TiVo,
VBox Home TV Gateway VBox Home TV gateway is a network-enabled live TV tuner and PVR HDTV set-top-box produced by VBox Communications Ltd. The VBox Home TV Gateway is also known as: * V@Home TV Gateway PVR * V@Home TV Gateway * VHome TV Gateway * VBox TV Gateway * ...
, and Kodi (formerly XBMC).


macOS

Geniatech makes a series of digital video recording devices called EyeTV. The software supplied with each device is also called EyeTV, and is available separately for use on compatible third-party tuners from manufacturers such as Pinnacle, TerraTec, and Hauppauge. SageTV provided DVR software for the Mac but no longer sells it. Previously sold devices support the Hauppauge HVR-950, myTV.PVR and HDHomeRun hardware with its DVR software. SageTV software also included the ability to watch YouTube and other online video with a remote control. MythTV (see above) also runs under
Mac OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lap ...
, but most recording devices are currently only supported under Linux. Precompiled binaries are available for the MythTV front-end, allowing a Mac to watch video from (and control) a MythTV server running under Linux. Apple provides applications in the FireWire software developer kit which allow any Mac with a FireWire port to record the MPEG2 transport stream from a FireWire-equipped cable box (for example: Motorola DCT62xx, including HD streams). Applications can also change channels on the cable box via the firewire interface. Only broadcast channels can be recorded as the rest of the channels are encrypted. ''FireRecord (formerly iRecord)'' is a free scheduled-recording program derived from this SDK.


Windows

There are several free digital video recording applications available for
Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...
including GB-PVR, MediaPortal, and Orb (web-based remote interface). There are also several
commercial Commercial may refer to: * a dose of advertising conveyed through media (such as - for example - radio or television) ** Radio advertisement ** Television advertisement * (adjective for:) commerce, a system of voluntary exchange of products and s ...
applications available including CyberLink, SageTV (which is no longer available after Google acquired it in June 2011), Beyond TV (which is considered discontinued despite an official announcement from SnapStream since the last update was October 2010 and they are concentrating on their enterprise search products), DVBViewer, Showshifter, InterVideo WinDVR, the
R5000-HD {{Unreferenced, date=November 2007 The Nextcom R5000-HD is a popular Windows-based system for digitally capturing HD ( high-definition) and SD (standard-definition) TV content from satellite TV and cable TV sources. A modification is required to ...
and Meedio (now a dead product – Yahoo! bought most of the company's technology and discontinued the Meedio line, and rebranded the software Yahoo! Go – TV, which is now a free product but only works in the U.S.). Most TV tuner cards come bundled with software which allows the PC to record television to hard disk. See TV tuner card. For example, Leadtek's WinFast DTV1000 digital TV card comes bundled with the WinFast PVR2 software, which can also record analog video from the card's
composite video Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channe ...
input socket. Windows Media Center is a DVR software by Microsoft which was bundled with the Media Center edition of Windows XP, the Home Premium / Ultimate editions of
Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...
, as well as most editions of
Windows 7 Windows 7 is a major release of the Windows NT operating system developed by Microsoft. It was Software release life cycle#Release to manufacturing (RTM), released to manufacturing on July 22, 2009, and became generally available on October 22, ...
. When Windows 8 was released in 2012, Windows Media Center was not included with Windows 8 OEM or Retail installations, and was only available as a $15 add-on pack (including DVD Playback codecs) to Windows 8 Pro users.


Embeddable

An ''embeddable'' DVR is a standalone device that is designed to be easily integrated into more complex systems. It is typically supplied as a compact, bare circuit board that facilitates mounting it as a subsystem component within larger equipment. The control keypad is usually connected with a detachable cable, to allow it to be located on the system's exterior while the DVR circuitry resides inside the equipment.


Source video

Television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertising, ...
and
video Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) sy ...
are terms that are sometimes used interchangeably, but differ in their technical meaning. Video is the visual portion of television, whereas television is the combination of video and audio modulated onto a
carrier frequency In telecommunications, a carrier wave, carrier signal, or just carrier, is a waveform (usually sinusoidal) that is modulated (modified) with an information-bearing signal for the purpose of conveying information. This carrier wave usually has a ...
(i.e., a television channel) for delivery. Most DVRs can record both video and audio.


Analog sources

The first digital video recorders were designed to record
analog television Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog ...
in
NTSC The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
, PAL or
SECAM SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...
formats. To record an analog signal a few steps are required. In the case of a television signal, a television tuner must first demodulate the radio frequency signal to produce baseband video. The video is then converted to digital form by a
frame grabber A frame grabber is an electronic device that captures (i.e., "grabs") individual, digital still frames from an analog video signal or a digital video stream. It is usually employed as a component of a computer vision system, in which video fram ...
, which converts each video image into a collection of numeric values that represent the
pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the ...
s within the image. At the same time, the audio is also converted to digital form by an analog-to-digital converter running at a constant sampling rate. In many devices, the resulting digital video and audio are compressed before recording to reduce the amount of data that will be recorded, although some DVRs record uncompressed data. When compression is used, video is typically compressed using formats such as H.264 or MPEG-2, and audio is compressed using AAC or MP3.


Analog broadcast copy protection

Many consumer DVRs implement a copy-protection system called ''Copy Generation Management System—Analog'' ( CGMS-A), which specifies one of four possible copy permissions by means of two bits encoded in the
vertical blanking interval In a raster scan display, the vertical blanking interval (VBI), also known as the vertical interval or VBLANK, is the time between the end of the final visible line of a frame or field and the beginning of the first visible line of the next fra ...
: * Copying is freely allowed * Copying is prohibited * Only one copy of this material may be made * This is a copy of material for which only one copy was allowed to be made, so no further copies are allowed. CGMS-A information may be present in analog broadcast TV signals, and is preserved when the signal is recorded and played back by analog VCRs. VCRs do not understand the meanings of the bits but preserve them in case there is a subsequent attempt to copy the tape to a DVR. DVRs such as TiVo also detect and act upon analog protection systems such as
Macrovision TiVo Corporation, formerly known as the Rovi Corporation and Macrovision Solutions Corporation, was an American technology company. Headquartered in San Jose, California, the company is primarily involved in licensing its intellectual property ...
and DCS Copy Protection which were originally designed to block copying on analog VCRs.


Digital sources

Recording digital signals is generally a straightforward capture of the binary
MPEG The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by ISO and IEC that sets standards for media coding, including compression coding of audio, video, graphics, and genomic data; and transmission and f ...
data being received. No expensive hardware is required to quantize and compress the signal (as the television broadcaster has already done this in the studio). DVD-based PVRs available on the market as of 2006 are not capable of capturing the full range of the visual signal available with
high-definition television High-definition television (HD or HDTV) describes a television system which provides a substantially higher image resolution than the previous generation of technologies. The term has been used since 1936; in more recent times, it refers to the g ...
(HDTV). This is largely because HDTV standards were finalized at a later time than the standards for DVDs. However, DVD-based PVRs can still be used (albeit at reduced visual quality) with HDTV since currently available HDTV sets also have standard A/V connections.


ATSC broadcast

ATSC television broadcasting is primarily used in North America. The ATSC data stream can be directly recorded by a digital video recorder, though many DVRs record only a subset of this information (that can later be transferred to DVD). An ATSC DVR will also act as a
set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of s ...
, allowing older televisions or monitors to receive digital television.


=Copy protection

= The U.S.
FCC The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdictio ...
attempted to limit the abilities of DVRs with its " broadcast flag" regulation. Digital video recorders that had not won prior approval from the FCC for implementing "effective"
digital rights management Digital rights management (DRM) is the management of legal access to digital content. Various tools or technological protection measures (TPM) such as access control technologies can restrict the use of proprietary hardware and copyrighted works. ...
would have been banned from
interstate commerce The Commerce Clause describes an enumerated power listed in the United States Constitution ( Article I, Section 8, Clause 3). The clause states that the United States Congress shall have power "to regulate Commerce with foreign Nations, and amo ...
from July 2005, but the regulation was struck down on May 6, 2005.


DVB

DVB Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) o ...
digital television Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative adva ...
contains audio/visual signals that are broadcast over the air in a digital rather than
analog format Analog recording is a technique used for the recording of analog signals which, among many possibilities, allows analog audio for later playback. Analog audio recording began with mechanical systems such as the phonautograph and phonograph. L ...
. The DVB data stream can be directly recorded by the DVR. Devices that can use external storage devices (such as
hard disks A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magneti ...
, SSDs, or other flash storage) to store and recover data without the aid of another device are sometimes called telememory devices.


Digital cable and satellite television

Recording satellite television or digital cable signals on a digital video recorder can be more complex than recording analog signals or broadcast digital signals. There are several different transmission schemes, and the video streams may be encrypted to restrict access to subscribers only. A satellite or cable
set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of s ...
both decrypts the signal if encrypted, and decodes the MPEG stream into an analog signal for viewing on the television. In order to record cable or satellite digital signals the signal must be captured after it has been decrypted but before it is decoded; this is how DVRs built into set-top boxes work. Cable and satellite providers often offer their own digital video recorders along with a service plan. These DVRs have access to the encrypted video stream, and generally enforce the provider's restrictions on copying of material even after recording.


DVD

Many DVD-based DVRs have the capability to copy content from a source DVD (ripping). In the United States, this is prohibited under the Digital Millennium Copyright Act if the disc is encrypted. Most such DVRs will therefore not allow recording of video streams from encrypted movie discs.


Digital camcorders

A digital
camcorder A camcorder is a self-contained portable electronic device with video and recording as its primary function. It is typically equipped with an articulating screen mounted on the left side, a belt to facilitate holding on the right side, hot-sw ...
combines a camera and a digital video recorder. Some DVD-based DVRs incorporate connectors that can be used to capture digital video from a camcorder. Some editing of the resulting DVD is usually possible, such as adding chapter points. Some digital video recorders can now record to solid state flash memory cards (called ''flash camcorders''). They generally use Secure Digital cards, can include wireless connections (Bluetooth and Wi-Fi), and can play SWF files. There are some digital video recorders that combine video and graphics in real time to the flash card, called DTE (Direct To Edit), DTE or "direct to edit". These are used to speed-up the editing workflow in video and television production, since linear videotapes do not then need to be transferred to the edit workstation (see Non-linear editing system).


File formats, resolutions and file systems

DVRs can usually record and play H.264/MPEG-4 AVC, H.264, MPEG-4 Part 2, MPEG-2 .mpg, MPEG-2 .MPEG transport stream, TS, VOB and ISO images video, with MP3 and Dolby AC-3, AC3 audio tracks. They can also display images (JPEG and Portable Network Graphics, PNG) and play music files (MP3 and Ogg). Some devices can be firmware, updated to play and record in new formats. DVRs usually record in proprietary file systems for copy protection, although some can use File Allocation Table, FAT file systems. Recordings from standard-definition television usually have 480p/i/576p/i while HDTV is usually in 720p/1080i.


Applications


Security

Digital video recorders configured for physical security applications record video signals from closed-circuit television cameras for detection and documentation purposes. Many are designed to record audio as well. DVRs have evolved into devices that are feature rich and provide services that exceed the simple recording of video images that was previously done through VCRs. A DVR CCTV system provides a multitude of advanced functions over VCR technology including video searches by event, time, date and camera. There is also much more control over quality and frame rate allowing disk space usage to be optimized and the DVR can also be set to overwrite the oldest security footage should the disk become full. In some DVR security systems remote access to security footage using a PC can also be achieved by connecting the DVR to a LAN network or the Internet. Some of the latest professional digital video recorders include video analytics firmware, to enable functionality such as 'virtual tripwire' or even the detection of abandoned objects on the scene. Security DVRs may be categorized as being either PC-based or embedded system, embedded. A PC-based DVR's architecture is a classical personal computer with video capture cards designed to capture video images. An embedded type DVR is specifically designed as a digital video recorder with its operating system and
application software Application may refer to: Mathematics and computing * Application software, computer software designed to help the user to perform specific tasks ** Application layer, an abstraction layer that specifies protocols and interface methods used in a ...
contained in firmware or read-only memory.


Hardware features

Computer hardware, Hardware features of security DVRs vary between manufacturers and may include but are not necessarily limited to: * Designed for 19-inch rack, rack mounting or desktop configurations. * Single or multiple video inputs with connector types consistent with the analogue or digital video provided such as coaxial cable, twisted pair or optical fiber cable. The most common number of inputs are 1, 2, 4, 8, 16 and 32. Systems may be configured with a very large number of inputs by networking or Bus (computing), bussing individual DVRs together. * Looping video outputs for each input which duplicates the corresponding input video signal and connector type. These output signals are used by other video equipment such as matrix switchers, multiplexers, and video monitors. * Controlled outputs to external video display monitors. * Front panel switches and indicators that allow the various features of the machine to be controlled. * Network connections consistent with the network type and utilized to control features of the recorder and to send and/or receive video signals. * Connections to external control devices such as Computer keyboard, keyboards. * A connection to external pan-tilt-zoom drives that position cameras. * Internal CD, DVD, VCR devices typically for archiving video. * Connections to external storage media. * Alarm event inputs from external security detection devices, usually one per video input. * Alarm event outputs from internal detection features such as motion detection or loss of video.


Software features

Software features vary between manufacturers and may include but are not necessarily limited to: * User-selectable image capture rates either on an all input basis or input by input basis. The capture rate feature may be programmed to automatically adjust the capture rate on the occurrence of an external alarm or an internal event * Selectable image resolution either on an all input basis or input by input basis. The image resolution feature may be programmed to automatically adjust the image resolution on the occurrence of an external alarm or an internal event. * Compression methods determine quality of playback. H.264 hardware compression offers fast transfer rates over the Internet with high quality video. * Motion detection: Provided on an input by input basis, this feature detects motion in the total image or a user definable portion of the image and usually provides sensitivity settings. Detection causes an internal event that may be output to external equipment and/or be used to trigger changes in other internal features. * Lack of motion detection. Provided on an input by input basis, this feature detects the movement of an object into the field of view and remaining still for a user definable time. Detection causes an internal event that may be output to external equipment and/or used to trigger changes in other internal features. * Direction of motion detection. Provided on an input by input basis, this feature detects the direction of motion in the image that has been determined by the user as an unacceptable occurrence. Detection causes an internal event that may be output to external equipment and/or be used to Event-driven programming, trigger changes in other internal features. * Routing of input video to video monitors based on user inputs or automatically on alarms or events. * Input, time and date stamping. * Alarm and event logging on appropriate video inputs. * Alarm and event search. * One or more sound recording channels. * Archiving, Archival.


Privacy concerns

Some (very few), but certainly not all, digital video recorders which are designed to send information to a service provider over a telephone line or Internet (or any other way) can gather and send real-time data on users' viewing habits. This problem was noted back in 2000 and was still considered a problem, specifically with TiVo, in 2015.


Television advertisements

Digital video recorders are also changing the way television programs advertise products. Watching pre-recorded programs allows users to fast-forward through commercials, and some technology allows users to remove commercials entirely. Half of viewers in the United States, for example, use DVRs to skip commercials entirely. This feature has been controversial for the last decade, with major television networks and movie studios claiming it violates copyright and should be banned. In 1985, an employee of Honeywell's Physical Sciences Center, David Rafner, first described a drive-based DVR designed for home TV recording, time shifting, and commercial skipping. U.S. Patent 4,972,396 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. The first DVR which had a built-in commercial skipping feature introduced in 1999 by
ReplayTV ReplayTV was a former DVR company that from 1999 until 2005, produced a brand of digital video recorders (DVR), a term synonymous with ''personal video recorder'' (PVR). It is a consumer video device which allows users to capture television progr ...
at the
Consumer Electronics Show CES (; formerly an initialism for Consumer Electronics Show) is an annual trade show organized by the Consumer Technology Association (CTA). Held in January at the Las Vegas Convention Center in Winchester, Nevada, United States, the event t ...
in Las Vegas. In 2002, five owners of the ReplayTV DVR sued the main television networks and movie studios, asking the federal judge to uphold consumers' rights to record TV shows and skip commercials, claiming that features such as commercial skipping help parents protect their kids from excessive consumerism. ReplayTV was purchased by SONICblue in 2001 and in March 2003, SONICblue filed for Chapter 11 bankruptcy after fighting a copyright infringement suit over the ReplayTV's ability to skip commercials. In 2007, DirecTV purchased the remaining assets of ReplayTV. A Third-party software component, third-party add-on for Windows Media Center called "DVRMSToolbox" has the ability to skip commercials. There is a command-line program called Comskip that detects commercials in an MPEG-2 file and saves their positions to a text file. This file can then be fed to a program like MEncoder to actually remove the commercials. Many speculate that television advertisements will be eliminated altogether, replaced by Product placement, advertising in the TV shows themselves. For example, ''Extreme Makeover: Home Edition'' advertises Sears, Roebuck and Company, Sears, Kenmore Appliances, Kenmore, Kohler Company, Kohler, and Home Depot by specifically using products from these companies, and some sports events like the Sprint Cup Series, Sprint Cup of NASCAR are named after sponsors. Another type of advertisement shown more and more, mostly for advertising television shows on the same channel, is where the ad overlays the bottom of the television screen, blocking out some of the picture. "Banners", or "logo bugs", as they are called, are referred to by media companies as Secondary Events (2E). This is done in much the same way as severe weather warnings are done. Sometimes, these take up only 5–10% of the screen, but in the extreme, can take up as much as 25% of the viewing area. Some even make noise or move across the screen. One example of this is the 2E ads for ''Three Moons Over Milford'' in the months before its premiere. A video taking up approximately 25% of the bottom-left portion of the screen would show a comet impacting into the moon with an accompanying explosion, during another television program. Because of this widely used new technology, advertisers are now looking at a new way to market their products on television. An excerpt from the magazine ''Advertising Age'' reads: "As advertisers lose the ability to invade the home, and consumer's minds, they will be forced to wait for an invitation. This means that they have to learn what kinds of advertising content customers will actually be willing to seek out and receive." With ad skipping and the time-sensitive nature of certain ads, advertisers are wary of buying commercial time on shows that are heavily digitally video-recorded. However, technology today makes it possible for networks to insert ads dynamically on videos being played in DVRs. Advertisers could inject time-relevant ads to recorded programs when the program is viewed. This way the ads could be not just topical but also personalized to viewers interests. DirecTV in March 2011 signed an arrangement with NDS Group to enable the delivery of such addressable advertisement. It is believed that viewers prefer to forward ads, than to switch the channel. By switching channels, viewers will have the probability of skipping the beginning of their program. Users might switch to a channel that is also showing ads. Having the ability to pause, rewind, and forward live TV gives users a chance to change the channel fewer times. Forwarding ads can have a later effect on the viewer. Ads that get the viewers' attention will influence the viewers' to rewind and watch what was missed. In January 2012, Dish Network announced Hopper service, costing $10 extra per month, which recorded prime-time programming from the four major broadcast networks. With the Auto Hop feature, viewers can watch the programs they choose without commercials, without making the effort to fast-forward. On May 24, 2012, Dish and the networks filed suit in federal court.


Patent and copyright litigation

On July 14, 2005, Forgent Networks filed suit against various companies alleging infringement on , entitled "Computer controlled video system allowing playback during recording". The listed companies included EchoStar, DirecTV, Charter Communications, Cox Communications, Comcast, Time Warner, and Cable One. Scientific-Atlanta and Motorola, the manufacturers of the equipment sold by the above-mentioned companies, filed a counter-suit against Forgent Networks claiming that their products do not violate the patent, and that the patent is invalid. The two cases were combined into case 6:06-cv-208, filed in the United States District Court for the Eastern District of Texas, Tyler Division. According to court documents, on June 20, 2006, Motorola requested that the United States Patent and Trademarks Office reexamine the patent, which was first filed in 1991, but has been amended several times. On March 23, 2007, Cablevision Systems Corp lost a legal battle against several Hollywood studios and television networks to introduce a network-based digital video recorder service to its subscribers. However, on August 4, 2008, Cablevision won its appeal. John M. Walker Jr., a Second Circuit judge, declared that the technology "would not directly infringe" on the media companies' rights. An appeal to the Supreme Court was rejected. In court, the media companies argued that network digital video recorders were tantamount to video-on-demand, and that they should receive license fees for the recording. Cablevision and the appeals court disagreed. The company noted that each user would record programs on his or her own individual server space, making it a DVR that has a "very long cord." In 2004, TiVo sued EchoStar Corp, a manufacturer of DVR units, for patent infringement. The parties reached a settlement in 2011 wherein EchoStar pays a one-time fee (in three structured payments) that grants Echostar full rights for life to the disputed TiVo patents upon first payment(as opposed to indefinite and escalating license fees to be constantly renegotiated), and Echostar granted TiVo full rights for life to certain Echostar patents and dropped their counter-suit against TiVo. In January 2012, AT&T settled a similar suit brought by TiVo claiming patent infringement (just as with Echostar) in exchange for cash payments to TiVo totaling $215 million through June 2018 plus "incremental recurring per subscriber monthly license fees" to TiVo through July 2018, but grants no full lifetime rights as per the Echostar settlement. In May 2012, Fox Broadcasting Co. v. Dish Network, LLC, Fox Broadcasting sued Dish Network, arguing that Dish's set-top box with DVR function, which allowed the users to automatically record prime-time programs and skip commercials, was copyright infringement and breach of contract. In July 2013, the 9th circuit rejected Fox's claims.


See also

* Set-top box * Home theater PC (Media PC) * Digital media player * Smart TV * Comparison of PVR software packages * 10-foot user interface * Content Reference Identifier, CRID * Direct-to-disk recording * DTE (Direct To Edit) * DTVPal * Freeview+ * Freesat+ * Hopper (DVR) * * Media server (Consumer) * Time shifting * Space shifting (place shifting) * Remote storage digital video recorder * MythTV * Network video recorder * SubRip * Sky+ * Tablo (DVR) * TiVo * TV-Anytime * PVR-resistant advertising * Remote control * USB hard disk * USB On-The-Go * Vu+ * Video server (Broadcast) * Kodi (software) * Xbox One


Notes


References


Free-to-Air Television and other PVR Challenges in Europe
, technical report of the European broadcasting union {{DEFAULTSORT:Digital Video Recorder Digital video recorders, Digital media, Video recorder Set-top box Television terminology