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HISTORY The first DVR was tested on July 8th, 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 analog video onto a digital hard disk and could store a maximum of only 30 seconds. PERSONAL VIDEO RECORDER (PVR) The personal video recorder ('''PVR''') or '''digital personal video recorder''', is a Consumer Electronics device that records Television shows to digital storage. Hard disk-based PVRs 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 DVD s, 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, 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+ . Many satellite and cable companies are incorporating DVR functions into their Set-top Box , such as with DirecTiVo , DishPlayer/DishDVR, Scientific Atlanta Explorer 8xxx, 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. DVD-based PVRs DVD-based PVRs, which can record onto CD or DVD blanks, first appeared on the consumer market in 1999 in Japan , and then in 2000 in the rest of the world. Early units were priced between 2500 and 4000 USD . As of early 2006 , substantial increases in the quantities available and in the number of retail outlets selling DVD-based PVRs have resulted in price reductions of approximately 90% compared to prices in 2000. The DVD-based PVR was anticipated to be the natural successor to the VCR for several technical reasons:
One disadvantage of DVD-based PVRs compared to VCRs is cost. Prices, however, drastically reduced (in the UK, the majority of recorders are around the £100 mark with some available for as little as £69.99). The downward pressure on the prices of recorders and recordable discs due to increased supply and market competition is likely to soon eliminate any disadvantage of having a DVD Recorder over a VCR. Another notable disadvantage is that DVD-based PVRs require some extra time both to initially format the disc for recording and to finalize the disc once recording has been stopped. This disadvantage does not apply to DVD-RAM disks, which behave more like a hard disk and require no finalization. PCs Software and hardware is available which can turn personal computers running Microsoft Windows , Linux and Macintosh into PVRs, and is a popular option for Home-theater PC (HTPC) enthusiasts. Linux and GPL -licensed DVR applications for Linux . KnoppMyth Linux distribution provides a out of the box MythTV based PVR solution Brightbox , a Consumer Electronics device, uses an OEM Linux solution from SageTV. Commercial Linux version available from SageTV based on Gentoo Linux. Macintosh Elgato makes a series of DVR devices called EyeTV (400 / 500 / DTT etc.). The software supplied with each device (but available separately) is also called EyeTV . Elgato have recently released version 2.0 of their EyeTV software, with a redesigned interface, better program guide (built into the program) and a 'One Click' to iPod video feature. Various rumor sites from the Mac Rumors Community have suggested Apple is working on PVR software, dubbed a ' TIVO -killer' and that this may be added to Front Row 2.0 and included with a 'Media Center' edition of the Mac Mini. Apple provides applications in the FireWire software developer kit which allows any Macintosh with a FireWire port to record the MPEG2 transport stream from a FireWire equipped cable box. Only broadcast channels can be recorded as the rest of the channels are encrypted. Windows Microsoft Windows has several free DVR applications including GB-PVR and MediaPortal . DScaler has also DVR support in works. There also are several , Meedio (now a dead product - Yahoo bought most of the company's technology and discontinued the Meedio line), InterVideo WinDVR , Recordit Plus and the R5000-HD . There is also a separate version of Microsoft Windows called Windows XP Media Center Edition which has DVR capabilities. Source video Television and Video are terms that are sometimes used interchangeably, but differ in their technical definitions. Video is the visual portion of television, whereas television is the combination of video and audio Modulated onto a Carrier Frequency (i.e., a television channel), so that multiple frequencies (i.e., multiple channels) may be transmitted at the same time. Analog television --> To record an analog signal a few steps are required. A TV Tuner Card Tunes into a particular frequency and then functions as a Frame Grabber , breaking the lines into individual pixels and Quantizing them into a format that a computer can comprehend. Then the series of frames along with the audio (also Sampled and quantized) are compressed into a manageable format, like MPEG-2 , or WMF , usually in software. Some TV tuner cards like the DVR-250/350 or the TiVo chip deliver an ''MPEG-2'' or other compressed stream directly to the computer, performing both the frame grabbing and compression In Silico . This greatly reduces the Load on the CPU allowing an overall cheaper implementation. Analog Broadcast Copy Protection Many mass-produced consumer DVRs implement a copy-protection system called CGMS-A ('''Copy Generation Management System--Analog'''). This encodes a pair of bits in the VBI of the analog video signal that specify one of the following settings:
CGMS-A information may be present in analog broadcast TV signals, and is preserved when the signal is recorded and played back by analog VCR s, which of course don't understand the meanings of the bits. But the restrictions still come into effect when you try to copy the tape onto a PVR. Digital television Digital Television is audio/visual signals that are broadcast over the air in a Digital rather than Analog format. Recording digital TV is generally a straightforward capture of the binary MPEG-2 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). The MythTV DVR supports both European DVB signals and American ATSC signals while the ''HDTV Tivo'' supports only the ATSC signals. In the U.S. , the FCC attempted to place a road-block before digital DVRs with its " Broadcast Flag " regulation. Digital video recorders which had not won prior approval from the FCC for implementing "effective" Digital Rights Management would have been banned from Interstate Commerce as of July 2005. The regulation was struck down on 6 May 2005. 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 (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. Satellite or Digital Cable Recording Satellite or Digital Cable signals on a digital video recorder is more complex than recording analog signals or broadcast digital signals. This is so because the MPEG-2 stream is usually encrypted to prevent people from viewing the content without paying for it (usually via subscription to a valid satellite decryption box and a decoder card). The satellite or cable decoder box does two things. First it decrypts the signal. Second, it decodes the MPEG-2 stream into an analog signal for play on the television. In order to record cable/satellite digital signals you would need to get the signal after it is decrypted but before it is decoded (between steps one and two). An alternative is that some satellite/cable decoder boxes have a FireWire port that can be connected to a computer. The MPEG stream could be relayed to the computer via this firewire port although there is as yet few, if any, current cards or devices that allow for a firewire connection to the computer from this box. DVD Many DVD-based DVRs are equipped with two DVD drives or an additional internal hard drive. This arrangement can be used to copy content from a source DVD, which is disallowed in the US under the Digital Millennium Copyright Act if the disc is encypted. Most such DVRs will hence not allow recording of video streams from encrypted movie discs. Digital camcorders Some DVD-based DVRs incorporate a Firewire connector which can be used to capture digital video from a Mini DV or Digital 8 camcorder, possibly recording a simple DVD as the camcorder is played back. Some editing of the resulting DVD is usually possible, such as adding chapter points. SECURITY APPLICATIONS In 2003 , the Yakima, Washington Police Department began using DVRs in their patrol cars to record the activities of officers and suspects. Since then, many other police departments have followed suit, due to the increased reliability and decreased cost compared to analog video systems. 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. Security DVRs may be categorized as being either PC based or Embedded . A PC based DVR’s architecture is a classical personal computer with Video Capture Card s designed to capture video images. An embedded type DVR is specifically designed as a digital video recorder with its Operating System and Application Software contained in Firmware or Read Only Memory . Hardware Features Hardware features of security DVRs vary between manufacturers and may include but are not necessarily limited to:
Software Features Software features vary between manufacturers and may include but are not necessarily limited to:
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