A digital video recorder (DVR) (or Personal Video Recorder (PVR)) is a device that records video without videotape to a hard disk based digital storage medium. The term includes stand-alone set-top boxes and software for personal computers which enables video recording and playback to and from your hard drive.
History
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The first DVR was testedJuly 8, 1965, when CBS carries the possibility of an immediate freeze and go back to the sporting event explored. Ampex released the first commercial hard disk video recorder in 1967. The HS-100 recorded analog video stored on a digital disk drive and can be a maximum of only 30 seconds.
Hard drive-based DVR
The first two consumer DVRs, ReplayTV and TiVo were launched at the 1999 Consumer Electronics Show in Las Vegas. Although ReplayTV won the "Best of Show" in videoCategory, it was TiVo that went into a much bigger commercial success. The devices are always complementary skills, such as DVD recording, commercial skip, sharing of recordings over the Internet and the possibility of programming and remote control via handheld devices, networked PCs or web-browser development.
This makes the "time shifting" feature (traditionally done by a VCR) much more convenient, and also allows the mode "trick", as Pause Live TV, instant replay of interestingScenes and skip commercials. Most DVR with MPEG format for encoding analog video signals.
The two consumer DVR brands in the United States are the TiVo and ReplayTV is dnna. In Britain, 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 + Sky. South Africa Africa Satellite TV beamer Multichoice recently launched their PVR DSTV is available on theirPlatform.
Many satellite and cable companies are incorporating DVR functions into their set-top boxes, such as Direct, DishPlayer / DishDVR, Scientific Atlanta Explorer 8xxx, Motorola 6xxx from Comcast, Moxi Media Center Dige (available through Charter, Adelphia, Sunflower, band Bend large, and soon Comcast and other cable companies) or Sky +. In this case there is no need for coding in the DVR, as the satellite signal is already encoded digital MPEG stream. The DVR simplystores the digital data stream directly to disk. Once the transmitter involved (subsidies) the design of the DVR - and directly recording encrypted digital streams - can be used for functions such as the possibility of interactive TV programs recorded, perform pre-loaded programs. But it can also force the manufacturer to implement non-skippable ads and hit autorun.
The software is available for transferring programs from DVR to PC Hardware or register(For example, TiVoToGo and DVArchive).
PC
Software and hardware available for PCs running Microsoft Windows, Linux and Macintosh can be transformed into PVR, and is a popular choice for home theater PC (HTPC) enthusiasts.
Linux
There are many open-source, GPL licensed DVR applications for Linux:
MythTV Freevo DVR VDR KnoppMyth - provides an out of the box MythTV based PVR solution
Commercial version of Linux available SageTVbased on Gentoo Linux. Brightbox, a consumer electronics device using SageTV. Macintosh
Elgato makes a series of DVR devices called EyeTV (400/500 / DTT, etc..) Software supplied with each unit (but sold separately) is also called EyeTV. Elgato has recently released version 2.3 of their EyeTV software, iPod with a revised interface, better program guide (integrated in the program) and a "One Click" to video function. Miles makes the hardware running EyeTV DVRSoftware and DVR units, to use the software.
Other products include DVR myTV.PVR Plextor ConvertX PVR and EskapeLabs. MythTV (see above) also works under OS X, but most recording devices are currently supported on Linux. Precompiled binaries are available for the MythTV frontend, so that watching videos from a Mac (and control) of a MythTV Linux servers.
Apple provides applications in the FireWire software developer kit, which allows allMacintosh with a FireWire port to record the MPEG2 transport stream from a FireWire cable box (for example Motorola 62xx, including HD streams). Applications can also be channels on the decoder via FireWire. Only the recorded broadcast channels, like the rest of the channels are encrypted. iRecord is a free program in the recording of the program derived from this SDK.
Windows
Microsoft Windows has several free DVR applications, including GB-PVR, Got All Media and MediaPortal.DScaler has DVR support in the works.
There are also some proprietary applications such as SageTV, SnapStream Beyond TV, ChrisTV, show shifter, Meedo (now dead product - Beginning purchased much of the technology and the company broke the line and re-branding of Singapore Software Meedo Go - TV which is now a free product), InterVideo WinDVR, RECORDIT Plus and R5000-HD.
There is also a separate version of Windows as Microsoft Windows XP Media Center Edition, which hasDVR functionality.
And Microsoft Windows Vista extends the standard version of Media Center features.
Video Source
Television and video are terms that are sometimes used interchangeably, but differ in their technical definitions. The video is the visual part of the television, while television is the combination of video and audio modulated on a carrier frequency (ie a TV channel), so that multiple frequencies (ie more channels)transmitted simultaneously.
Analog TV
Analog television formats NTSC, PAL and SECAM, analog cable, or regular VHS tapes with a signal fed directly to the electron beam within the television. There are a number of details, as this is done, but at the end of each line in each frame, a certain fraction of the time is within range.
To record an analog signal a few steps. A TV tuner card tracks in a specific frequency and thenIt works like a frame grabber, breaking the lines into individual pixels and quantizing in a format that a computer can understand. Then the series of images with the audio (also sampled and quantized) are manageable in a format such as MPEG-2, or WMF, usually compressed in software. Some TV tuner cards such as TiVo or DVR-250/350 chips to provide an MPEG-2 or other compressed directly to the computer, performing both the frame capture and compression in silico. Thisreduces the load on the CPU provides a comprehensive implementation cheaper.
Analog broadcast copy protection
Many mass-produced consumer DVRs implement a copy protection system called CGMS-A (generation of Copy Management System - Analog). It codes for a couple of bits in the VBI of the analog video signal that specify the following settings:
Copying is freely permitted Copying is prohibited A single copy of this material may be made This is a copy of the materialthat one copy could be made so that no additional copies are allowed.
CGMS-A analog broadcast TV signals into information, and is preserved when the signal is recorded by analog VCRs and understand what is not, of course, played the meanings of the bits. But the restrictions come into force when you try to copy the tape on a player. Digital TV
Digital TV has audio / video signals that are transmitted digitally over the airinstead of analog format. Recording digital TV is usually a simple recording of the binary MPEG-2 data received. No expensive hardware is required in order to quantize and compress the signal (such as the broadcaster has already done in the studio). The MythTV DVR supports both international DVB signals and American ATSC signals while the HDTV Tivo supports only the ATSC signals. In the U.S., the FCC has tried to place a block before digital DVRs place with its "broadcast flag"Regulation. Digital video recorders which had not obtained prior approval from the FCC to implement management "effective" digital rights would have been banned from interstate commerce since July 2005. The regulation was adopted on 6 May 2005 Taken.
DVD-based PVRs on the market since 2006 is not able to capture the entire spectrum of the visual signal for high-definition television (HDTV) are. This is largely because HDTV standards at a later time than the completed ones wereStandard for DVDs. However, DVD-based PVRs are still in use (albeit lower quality) with HDTV since currently available HDTV set connectors Standard A / V
Satellite or digital cable
Recording satellite or digital cable signals on a digital video recorder is more complex than recording analog signals or digital signals transmitted. This is because the flow of MPEG-2 or MPEG-4 is usually encrypted to prevent people from viewing the content without paying(Usually by subscription).
The set-top cable or satellite does two things. First, decode the signal. Second, it decodes the MPEG stream into an analog signal, DVI or HDMI to display on your TV. For cable / satellite record digital signals you must get the signal after it has been decrypted, but before being decoded (between steps one and two), which is like DVR set-top boxes built work.
The alternative is that some satellite or (more commonly) cable set-topBoxes have a FireWire port can be connected to a computer. The recorded MPEG stream can be transmitted to the computer via the FireWire port, although they live in can be done, this is often used for the transmission of programs from a set-top boxes with built-in DVR. (For instructions on how to do it on a popular set-top box with DVR, please see the Wikibook entry How to use a Motorola DVR, some of the ideas that can be applied to other set-top boxes as well.)
DVD
Many DVD-based DVRs are equippedwith two DVD discs, or an additional internal hard drive. This arrangement can be used to provide content from a DVD source, which is not allowed by the U.S. Digital Millennium Copyright Act, if the disk is encrypted copy. Most of these DVR therefore not allow recording of video streams from encrypted disks films.
Digital Cameras
Some DVD-based DVRs include a Firewire port, you can make digital video from a MiniDV or Digital 8 camcorder, possibly recording aDVDs as simple as the camera is played. Some editing functions of the resulting DVD is usually possible, such as adding chapter points.
Security Applications
Digital video recorder to record video signals from physical security CCTV cameras for detection and documentation. Many are designed to record audio. DVRs are devices that are feature rich and provides services that exceed the simple recording of video images developedthat was previously done through VCRs. A DVR CCTV system provides a set of functions over VCR technology including advanced video search event, date, time and camera. There are also a lot more control over quality and frame rate allowing disk space usage and to optimize the DVR can be ignored for the movie's oldest security if the disk is full. In some DVR security systems remote access to security video using a PC can also be obtained by connecting the DVR,LAN or Internet.
Security DVRs may be embedded or PC-based classification. A PC-based DVR is a classical computer architecture staff with video capture cards to capture video images. A type of embedded DVR is specifically included as a digital video recorder with its operating system and application software in firmware or read-only memory designed.
Hardware Features
Hardware features of security DVRs by manufacturer and caninclude but are not necessarily limited to:
Designed for rack mounting or desktop configurations. Single or multiple video inputs with connector types consistent with the analog video or digital, such as coaxial cable, twisted pair or fiber optic cable. The most common number of inputs 1, 4, 8, 16 and 32. The systems can be configured with a large number of inputs in the network or bussing individual DVRs. Looping video outputs for each input which duplicatesthe appropriate video input signal and connector type. These output signals are used by other video devices such as routers, multiplexers, and video monitor. Outputs controlled by external video monitor. Switches and indicators on the front, the various machine functions can be controlled. Network connections in accordance with the type of network and are used to control the functions of the recorder and to send and / or receiving video signals. Connectionsexternal control devices such as keyboards. Links to external pan-tilt-zoom cameras that drive position. Internal CD, DVD, VCR devices typically for archiving video. Connections to external storage media. Alarm on input from external security detection, usually one for each video input. Alarm outputs from internal detection function, such as motion detection or video loss.
Software Features
Features of the software according to the manufacturer, and mayinclude but are not necessarily limited to:
User selectable image capture rate is based on all the input or input-based. The capture rate feature may be programmed to automatically capture rates when an external alarm or an internal event Resolution is based on all inputs or input from input-based. The resolution function can be programmed to automatically image resolution when an external alarmor an internal event. Motion detection: Provided on an input that recognizes the basic input detection function of the movement in the whole image or a definable portion of the image, and usually provides sensitivity settings. Detection causes an internal event, the output of an external device and / or used to detect changes in other functions can be activated. The lack of motion detection. Provided to an input from input-based realize this function, the movement of an object in the visual field andothers available for a defined period. Detection causes an internal event, the output of an external device and / or used to detect changes in other functions can be activated. Direction of motion detection. Provided to an input from input-based realize this function, the direction of motion in the image, which was determined by the user as an unacceptable fact. Detection causes an internal event that can be output to external devices and / or be used to trigger changes in otherfunctions. A path of video for video monitors on user input or automatically on alarms or events. Entry, date and time. Alarm and event logging to the appropriate video inputs. Alarms and events search. One or more channels of audio recording. Archive. Remote control.
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