Digital video recorder

A digital video recorder, or DVR, is a term that defines a client electronics item or application program that may record video as a digital file to a USB drive, SD Card for data storage, disc storage.And it’s not the full list of the memory devices. This recorder also has another name – personal video recorder, or PVR, which is used in marketing in order to boost sales. This notion consists of set-top boxes which allow straightforward recording to a disc, handy media players allowing recording, camera-recorders which allow recording to SD Card for data storage and programs for PCs which offer an option for video capturing and playbacking to and from a hard disk device. LG released a TV set that has a video-recording equipment set in 2007. This technology became an example for other manufacturing companies.

Recently, the use of DVR has increased greatly. Thus, according to expert estimates, in January 2006 the share of U.S. households equipped with a DVR was equal to 1.2%. In February 2011 this share had raised significantly and was equal to 42.2%.

The history of digital video recorder

The introduction of consumer DVRs that have facilities for replaying TiVo and TV was made in 1999 in the United States. Microsoft launched an item having DVR facility as well. However it become possible to get an access to this item in 1999 when DISH Player-DVR receivers became accessible. First devices of TiVo came to the market the same year. ReplayTV also made attempts to launch some video recording facilities, but after a short period of time the company had to delete numerous options, including a possibility to spread recording via the Internet. However when new items were worked out, the developers used these options again, as well as added new ones. Thus, it was possible to program, record onto DVDs, execute remote control via web browsers, PCs connected to network and PDAs.

DVRs based on hard disc device has an option of time-shift keying. It’s very beneficial, because enables the users to immediately replay necessary scenes, pause live TV, remove advertising and chase playback. The digitized video signals are compressed in the MPEG format in DVRs.

Now a set-top box can’t work effectively without video recording facilities, because the owners of TV sets always had a desire to exercise control over what they watch. The option of capturing video and watching it then when the viewer has such a desire is now an obligatory facility for all owners of the TV sets. So the consumers converge great volume of video information by means of set-tops. This video may be delivered from various networks.

In 1999, Dish Network showed the hardware which could have DVR facility in future with the help of Microsoft programs. By the end of the same year the Dish player was equipped with all DVR features. As a result, more than 200,000 items have been sold for one year.

In the UK, DVRs are frequently regarded as plus boxes. British Sky Broadcasting markets enjoy wide popularity because of the mix of EPG and DVR as Sky+. This design was introduced in 2000 by TiVo, but it was discontinued. However even nowadays user maintenance exists.

Besides TiVo and ReplayTV, AC Ryan Playon, Pace Micro Technology, Topfield, Thomson, Advanced Digital Broadcast Fusion, and Humax also became the manufactures of digital terrestrial DVRs.

A lot of cable, IPTV and satellite providers build DVR facilities into the set-top boxes produced by them. The range of these providers is quite long. Some of their products became popular, others not, but it was an important stage of the development of DVRs.

Talking about digital television, it should be mentioned that encoding is not needed in DVR, because the signal is encoded in a digital format creating a MPEG file. The DVR acts saving the digital flow straightforwardly to disc. As the DVR is equipped with transmitting apparatus, this allows to enlarge its useful capabilities, including a possibility to preload television programmes, use interactive TV on recorded content and straightforwardly record encrypted bit streams. That’s why the manufacturers try to use advertisements that the user can’t skip, as well as recordings that expire in an automated mode.

In the US, the FCC issued a decree that allows consumers to buy a set-top box within a non-affiliated company. Consumers can’t be compelled to buy a set-top box within the cable company the services of which they use. This decree became valid on July 1, 2007. The regulation just obtains regarding navigational aids and doesn’t imply the safety features which may control the accessibility of the cable operator content. It’s hardly probable that the effectiveness of DVRs with related technology will exceed the effectiveness of self-supporting DVRs which are nowadays commercially available.

Numerous Satellite and Cable companies launched dual-tuner DVRs in 2003. BSkyB, the UK company, launched its first PVR Sky+ equipped with dual tuner in 2001. The devices are equipped with 2 autonomous tuners at the same receiver. This option is targeted on recording a live programme when the user is watching another on at the same time or on recording 2 programmes simultaneously, when the user is watching a programme recorded earlier. Kogan Technologies started to sell a dual-tuner PVR on the Australian market. It enables the users to record free television on a exchangeable hard disc drive. There are dual-tuner DVRs that can be output to 2 autonomous TV sets simultaneously. A few digital subchannels are broadcasted on a single RF channel. There are PVRs that feature an ability of recording 2 channels, while watching a third one. In the US, the share of DVRs use raised from 32 to 38% for one year – from 2009 to 2010.

Integrated television set

It’s a common practice to equip LED and LCD TV-sets with DVRs. This allows the user to easily wire and install what is necessary, as there is no need to apply ports. So the users may apply just one device, power and one remote control (earlier there were 2 ones). Some safety systems exist which are built into DVRs. Consequently these devices can record more input flows simultaneously. DVRs may have wireless ports, including Wi-Fi and Bluetooth, hence these devices record and play files to or from mobile phones and not only. These items may be also applied as disguised observation systems which display videos and pictures.

VESA-compliant DVR

Design of VESA-compliant DVR is compact. It’s a lightweight device. That’s why it can be fixed on the LCD monitor’s back which makes VESA mounting holes accessible. Their dimensions are 100×100mm. So the consumers have a possibility to apply own personal monitors in order not to waste money and save space in the house.

PC-based DVR

It’s possible to find hardware and software that may transform PCs operating on Mac OS X, Linux, and Microsoft Windows into DVRs. The owners of home-theater PCs especially like this useful option.

NAS digital video recorder

More and more pay-TV operators are giving their customers an opportunity to develop own digital recording platform that will be able to store photos, video and audio. Adjustable software and hardware platforms allow the customers to hook up NAS hard drive devices or solid-state and flash memory to set-top boxes if they are not equipped with own internal storage. This approach allows an operator to cut expenses allowing the customers to find a digital recording solution which satisfies all their needs.

Linux is compatible with numerous DVR applications which are free of charge. They refer to open source software, such as XBMC, MythTV, LinuxMCE, Mac OS and VDR.

Elgato manufactures multiple DVR items which have the name of EyeTV. Software that goes with every item also have the same name. It can be applied autonomously on compliant third-party tuners made by different manufacturers, including Hauppauge, Pinnacle, and TerraTec.

SageTV developed DVR programs for the use on the Mac, but now they are discontinued. The items that have been sold already are compatible with HDHomeRun, Hauppauge HVR-950, and myTV.PVR. The programs of mentioned company also provided an option of watching YouTube and other video content in the Internet with remote regulation.

MythTV operates on Mac OS X. However nowadays the major part of recording items operate just on Linux. The external interface of the MythTV has precompiled binaries that makes possible watching and controlling video from a MythTV server, while operating on Linux.

Apple offers apps in the FireWire software developer kit that enables any Mac equipped with a FireWire port to make recordings of the MPEG2 transport flow from a cable box with FireWire. Apps may also replace channels on the cable box throughout the FireWire interface. It’s possible to record just broadcast channels, because the other channels are encrypted.

Microsoft Windows has a few DVR applications which are free of charge. They are Orb, GB-PVR, and MediaPortal.

One can also distinguish a few commercial applications, such as CyberLink, Showshifter, the R5000-HD, InterVideo WinDVR, DVBViewer. There were some other similar applications but currently they are not available on the market. The major part of TV tuner cards makes up a set with software that enables a PC to make television recording to hard disc drive. Windows Media Center refers to a DVR program developed by Microsoft and it makes up a set with the Media Center edition of Windows XP, the Home Premium / Ultimate editions of Windows Vista, as well as most editions of Windows 7.

Source video

Very often, people interpret video and television as a single notion. However these notions have different technical essence. Video can be defined as a visual element of television. And television can be defined as a mix of audio and video which are transposed onto a central frequency, or in other words a television channel, for broadcast. DVRs are unique to some extent, because they record both of them.

The original DVRs were developed for recording analog television in PAL, SECAM and NTSC formats. Recording of an analog signal consists of several irreplaceable stages. TV tuner card alines into a needed frequency and after this works as a frame grabber. It breaks the lines making individual pixels and then discretizes them to a format which may be supported by the computer or other device. After this the groups of frames, as well as the audio, have to be subject to compression in order to receive a well-handled format, such as MPEG-2.

A lot of DVRs are targeted on mass consumption, so that they have a copy-protection system, widely known as CGMS-A. It encrypts a pair of bits to the VBI of the analog video signal. It has some types settings which have to be mentioned. Copying can be made without restrictions or it can be forbidden. Or it’s possible to copy just one material. It may also be stated that one copy of material has been already made and it’s forbidden to make other copies.

CGMS-A can be available in analog broadcast TV signals. It will be saved once a signal have been recorded. One can also playback it by analog VCRs. However there are some limitations on copying the tape onto a PVR.

TiVo refers to DVRs that function on analog protection systems, including DCS Copy Protection and Macrovision. These systems were initially developed for blocking any attempts of copying on analog VCPs.

If one records digital signals, this usually means a direct capturing of the binary MPEG information that have been received earlier. There is no need to purchase costly hardware for discretizing and clamping together the signal.

PVRs based on DVD are purchasable from 2006. But their facilities don’t allow them to capture all variety of the visual signals which are present in HDTV. This happened, as HDTV standards were worked out after creation of DVDs standards. But these PVRs may be applied with HDTV, because nowadays these TV sets are usually equipped with standard A/V connections.

Generally, ATSC television broadcasting is peculiar to North America. It’s possible to straightforwardly record the ATSC information flow applying a DVR. However, a lot of DVRs may record just a capsule version of received information. It can be also shifted to DVD. Mentioned DVR can function as a set-top box, hence if somebody has old monitor or TV set, he or she can enjoy digital television as well.

In the US, FCC tried to restrict the DVRs capabilities. The idea was to prohibit selling of the DVRs which couldn’t carry out digital right management. However this rule has been revoked.

DVB digital television consists of audio and visual signals which are transmitted in a digital format and rarely in analog format. DVR may straightforwardly record the DVB information flow. Self-supporting devices which may be kept in an external fixed disk storage can be defined as a telememory.

It has to be noted that it’s more difficult to record digital or satellite cable signals than to record analog signals or broadcast digital signals. One can determine a few transmission schemes. It’s possible to encode the video flows in order to limit the accessibility just for the users.

Cable set-top box can decode the signal that has been encoded earlier and decrypts the MPEG stream turning it into an analog signal in order it could be watched on the TV. For recording satellite digital signals, it’s necessary to capture a signal once it has been decrypted. It’s a principle of functioning of a set-top box equipped with a DVR. The providers of satellite and cable services generally provide own DVRs with attached service plan. The encrypted video stream is accessible with the help of these DVRs. Also, the devices compel the limitations of the provider. Thus, copying of material after it has been recorded can be prohibited.

A lot of DVRs which are based on DVDs can copy content from a DVD source. For instance, in the US the Digital Millennium Copyright Act bans copying in case that the disc has been encrypted. That’s why these DVRs don’t enable the users to record video streams from encrypted discs.

A digital camera recorder is a universal device featuring a DVR and a camera. There are DVRs based on DVDs that have built-in connectors which are employed for capturing digital video from a camera recorder. It’s generally possible to edit the received DVD, for example, add chapter points. There are also DVRs that are capable to record to flash camcorders. As a rule, they employ Secure Digital cards, may be equipped with wireless connections, such as Wi-Fi and Bluetooth, and are capable to play files in SWF format. It’s possible to find DVRs which make combinations of graphics and video recording them to the flash card. These devices are employed to fasten the editing workflow in television programmes and video. It’s not necessary to transfer linear videotapes to the edit workstation.


File formats

Generally, DVRs record and play MPEG-2 .TS, MPEG-4 Part 2, VOB and ISO images video, H.264, and AC3 and MP3 audio tracks. Also, the devices may display PNG and JPEG images and play MP3 files. There are DVRs that have an additional feature: it’s possible to update them in order to record and play the files in new formats. As a rule, DVRs make recordings by means of patented file systems in order to guarantee copy security. But some of the devices employ FAT file systems. TV DVRs work in accordance with the electronic programming guide.

DVR applications

DVRs formed for physical protection apps can record video signals from closed-circuit television cameras in order to detect and document different processes. A lot of the devices are also developed in order to record audio. The improvement of DVRs is obvious, because currently these devices have numerous capabilities and options and can render a lot of services. Now it’s a complicated devices and video recording is just one of its multiple functions. A DVR CCTV system offers many improved options through VCR technology. Thus, one can look for video by camera, time, even and date. This allows the users to control frame rate and quality and optimize the disc space usage. Also, one can adjust DVR for rewriting security footage. If one hooks up the DVR to the Internet or a LAN network, security footage will become accessible remotely. It’s possible if a security system of the devices allows this. There are newest professional DVRs that contain video analytics firmware enhancing effectiveness.

One can distinguish two types of security DVRs: embedded and PC-based. An embedded DVR is developed as a DVR which has own operating system and application programs that can be found in read-only memory and firmware. A PC-based DVR has a structure that resembles a usual personal computer equipped with video capture cards for capturing video.

Security DVRs made by different manufacturers have different hardware characteristics. Here are some of these characteristics, but it’s not a full list. The device is developed in such a way in order to allow rack mounting. It has different desktop configurations. It’s possible to input one or more video material by means of the connectors compatible with digital or analog video. The range of the cables that can be applied includes optical fiber cable, coaxial cable and twisted pair cable. 32, 16, 8, 4, 2 and 1 are the most widespread numbers for inputs. Short-circuit and networking are the ways of configuration of the systems. Moreover, the configuration has a great number of inputs. The output signals are employed by different video devices, including video monitors, matrix switchers and multiplexers. The system controls outputs to external video display monitors. Front face-plate indicators and commutators enable the users to exercise control over different capabilities of the device. Connectors of network are compatible with the kind of the network. They are employed in order to control the capabilities of the item, as well as receive and send video signals. Keyboards are used for connecting to external control devices. Cameras positioning is also possible by means of connecting to an external pan-tilt-zoom drive. The user may archive video employing internal VCR, DVD and CD devices. DVR may also be connected to external storage media. Alarm event inputs and outputs are available.

Different manufacturers also offer software with different characteristics. Some of them are listed further, but it’s not a complete range. The user may choose image capture rate. It can be programmed, so that the capture rate could be configured in an automated mode if external alarm or internal event happens. Image resolution may also be chosen. This characteristic can be programmed for configuring the image resolution in an automated mode if external alarm or internal event happens. Techniques of compression affect the playback quality. If the user chooses H.264 hardware compression, this ensures quick transfer rates via the Internet and results in video of top quality. Motion detection option registers motion in the image. Generally, it offers sensitivity adjustments. Detection leads to an internal event. It can be applied for activating changes in internal capabilities.

Motion detection shortage registers how an object moves into the viewing area and is kept still for a period of time determined by user. Detection leads to an internal event. It can be applied for activating changes in internal options.

The user may direct motion detection registering it in the image which has been distinguished by him as an event that can be suitable. Detection leads to an internal even and its use is similar to that in previous situations.

It’s possible to rout input video to video monitors which are grounded on the inputs of the user. Also, everything can be made in an automated mode by means of events and alarms. The user may stamp time, date and input; log alarms and events on correct video inputs, look for events and alarms, select one or more sound recording channels and archive video. The option of solving privacy issues is also available.

There are DVRs that may collect and send adequate information necessary for the user because these devices are developed for sending data to a service provider throughout the Internet or telephone.

Future TV Ads

DVRs became a product that promotes evolution of the TV advertisements. When the user watches a pre-recorded program, he or she may rewind promotional materials. There are technologies that enable the users to delete commercials completely. In recent years this option became speculative. The most of TV networks and film companies started to affirm that such a practice infringes law of copyright and hence must be prohibited.

1985 was marked by an important event in DVR development: David Rafner featured a drive-based DVR worked out for TV recording and commercial removal at home. Model of device highlighted availability of numerous channels enabling autonomous recording and playback at once. Then DVR evolved and new features have appeared, such as compression of video streams, possibility to capture, edit, observe multi-channel safety.

ReplayTV was the first company that launched DVR equipped with commercial skipping facility. The launch occurred in 1999. In 2002 the owners of the company filed lawsuit against the major TV networks and film companies defending consumers rights for recording TV programmes and commercials skipping. In their opinion, a possibility to remove commercials could help to reduce the level of consumerism, especially among children.

Comskip refers to software that identifies commercials in an MPEG-2 format saving their locations to a text format. After this the file will be send to a program, such as MEncoder, in order to skip commercials completely.

There is a discussion that TV commercials will be removed soon and instead of them TV shows commercials will be used. Also, the advertisements in the bottom of the TV screen are becoming more and more popular. These advertisements don’t allow to normally watch the picture. In some cases they account for 5-10% of the screen space, in others – up to 25% of it. These advertisements may move or even make sounds. A lot of the advertisers learn this technology and search for the new methods to promote their products on TV. The users try to use commercial skipping technologies, while the advertisers purchase commercial time on TV programmes which are very popular and often recorded by television viewers. Modern technologies allow the networks to add dynamic advertisements on videos which are played by means of DVRs. Also, advertisers may add time-sensitive advertisements to recorded shows when they are watched. Advertisers even try to personalize commercials in accordance with the interests and preferences of the viewers. In March 2011, DirectTV entered into contract with NDS Group in order to allow the use of these ads. The experts think that the viewers more often hasten commercials than change the channel. If the viewers change channels, they may miss the beginning of the show or programme. However if the viewer changes channel, there is a probability that at this moment ads are shown.

In 2005, Forgent Networks brought a case before a court against different companies claiming contravention of U.S. Patent 6,285,746. The list of these companies is quite long. In turn, Scientific-Atlanta and Motorola, which are the companies, manufacturing the equipment that is sold by the companies from the list, brought a counterclaim against Forgent Networks affirming that their equipment doesn’t contravene the patent. Besides this 2 cases, there were other similar discussions between the TV networks, movie studios and manufactures that lead to a court, where they debated over the issues of DVRs use. And these discussions continue till present time. Among the most recent, there is a case between AT&T and TiVo in January 2012. For AT&T it resulted, among others, in commitment to repay $215 million to TiVo till 2018.