A digital video recorder (DVR) (or personal video recorder (PVR)) is a device that records video without videotape to a hard drive-based digital storage medium. The term includes stand-alone set-top boxes and video playback software for PC, video capture and to and from the hard drive.
History
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TheDVR first was on July 8, 1965, tested a CBS examine the possibility of freeze-frame and rewind for instant broadcasting of sports events. Ampex released the first commercial hard disk video recorder in 1967. To save the HS-100 analog video recorded on a digital hard drive and can be a maximum of only 30 seconds.
Hard drive-based DVR
The first two consumer DVR, ReplayTV and TiVo are undertaken for the 1999 Consumer Electronics Show in Las Vegas. Although he won the ReplayTV"Best of Show Award in the video, was the TiVo was far greater commercial success. The devices have steadily developed complementary abilities, such as DVD recording, commercial skip, sharing of recordings over the Internet, programming and control options remotely via PDAs, networked PCs, or web browser.
This makes the time to "shift" feature (traditionally done by a VCR) much more convenient, and also allows for "trick modes" such as Pause 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 ReplayTV DNNA's. In the United Kingdom TiVo a small presence, Thomson, Topfield, Fusion, Pace and Humax also deliver digital terrestrial (DTT) DVRs. BSkyB markets a popular combined EPG and DVR as Sky +. South Africa Africa Satellite TV beamer Multichoice recently launched their PVR isDSTV on its platform.
Many satellite companies and cable DVR functions into their set-top boxes, such as directive, Dishplayer / DishDVR, Scientific Atlanta Explorer 8xxx, Motorola 6xxx from Comcast, Moxi Media Center Dige (available through Charter, Adelphia, to Sunflower, Bend Broadband, and soon Comcast and other cable companies) or Sky +. In this case, need not be encoded on the DVR, such as digital satellite signal is already encoded in MPEGFlow. The DVR simply stores the digital stream directly to disk. Following the lead channel with () the design of the DVR functions to subsidize directly and encrypted digital streams may participate, as the capacity for interactive TV to watch recorded TV programs, the use of pre-loading of programs. But it may also force the producer will not skip the ads and implement autorun recordings.
Software is available for transferPrograms included) on the DVR, or PC hardware (eg, TiVoToGo and DVArchive.
PC
Wheel of hardware and software available for PCs running Microsoft Windows, Linux and Macintosh PVR is possible, and is an important choice for Home Theater PC (HTPC) enthusiasts.
Linux
There are many open source and GPL license DVR applications available for Linux:
MythTV
Freevo
DVR
VDR
KnoppMyth – provides an out of the box MythTV based PVR solution
Commercial Linux version of SageTV is based on Gentoo Linux. Brightbox uses a device at the Consumer Electronics SageTV.
Macintosh
Elgato makes a series of devices to EyeTV DVR (400 / 500 / DTT, etc.). The software supplied with each device (but is available separately), as well as EyeTV. Elgato has released version 2.3 of EyeTV software, with a revised interface (better program guide built into the program) and a "One Click" to ipodFeature. Miles makes DVR hardware that runs the EyeTV software, and devices compatible with other DVR software.
Among other products DVR myTV.PVR of EskapeLabs and ConvertX PVR from Plextor. MythTV (see above) also works on OS X, but most recording devices are currently supported only on Linux. Precompiled binaries for the MythTV interface available, so a Mac to capture video from (and control clock) a MythTV server running under Linux.
Apple Introduces Applicationsin the FireWire software developer kit, which includes all FireWire-equipped Macintosh with the MPEG2 transport stream from a FireWire cable box (for example Motorola 62xx, including HD streams possible.) Applications may also be the channels of the cable box via FireWire. Only broadcast channels can be recorded as the rest of the channels are encrypted. iRecord is a free program-recording program derived from this SDK.
Windows
Microsoft Windows has several free DVRApplications including GB-PVR, Got All Media and Media Portal. DScaler has support DVR in the works.
There are also some proprietary applications like SageTV, SnapStream Beyond TV, ChrisTV, exchange show, Meedio (now a dead product – Yahoo! Bought most of the company's technology and discontinued the line Meedio, and re-branding of the software from Yahoo ! Go – TV, which is now a free product), InterVideo WinDVR, RECORDIT Plus and the R5000-HD.
There is also a separate version ofMicrosoft Windows and Windows XP Media Center Edition, which offers DVR functionality.
Microsoft Windows Vista and is in its standard version, the functionality of Media Center.
Video Source
TV and video are terms that are sometimes used interchangeably, but differ in their technical definitions. Video is the visual part of television, whereas television is the combination of video and audio data to a carrier frequency (ie modulated, TVChannel), so that multiple frequencies (for example) more channels can be transmitted at the same time.
Analogue
Analog television in NTSC, PAL or SECAM formats, analog cable, or regular VHS tapes use a signal which is fed directly to the electron beam on television. There are a number of details, as it happened, but basically every line in each frame of a certain fraction of the time corresponds to the signal.
To record an analog signal a few stepsneeded. A TV tuner tunes in a specific frequency and then as a frame grabber, breaking the lines into individual pixels and the quantization in a format that a computer can understand. Then the series of images 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 TiVo or the chip DVR-250/350 carrying an MPEG-2 or other compressed stream directly to your computerThe implementation of both Grab frame and compression in silicon. This reduces the load on the CPU allowing an overall cheaper implementation.
Broadcast Analog 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 define one of the following settings:
Copying permitted freely
You may not copy
Only A copy of this material may be made
This is a copy of the material of which only one copy may be made in a way that does not allow for additional copies.
CGMS-A information may exist in analog TV broadcasts, and is preserved when the signal and re-recorded by analog recorders that do not understand, of course, the meaning of the bit player. But like the restrictions still in force when you try to copy the tape of a player.
Digital TV
> Digital television signals and audio / visual that are sent over the air, in a digital format rather than analog. Recording digital TV is received will normally be a simple collection of MPEG-2 data tracks. No expensive hardware is required to quantize and compress the signal (as the issuer) has already been done in the studio. MythTV DVR supports both international and supports DVB and ATSC American, while the Tivo HD signalsATSC signals. In USA, the FCC has tried to block a road, first with his DVR digital "broadcast flag" regulation. Digital video recorders which had not won, should have been previously approved by the FCC for implementing "effective" digital rights management from the prohibition of Interstate Commerce in July 2005. The regulation was published May 6, 2005 dejected.
DVD-based PVRs on the market since 2006 are not able to capture the entire spectrum of visualAvailable with high-definition television (HDTV) signal. This is largely because HDTV standards were finalized at a later date than that of standard DVDs. However, DVD-based PVRs can still be used (albeit with a worsening of image quality) with HDTV HDTV equipment available today has also standard A / V connections.
Satellite or digital cable
Recording signals via satellite or digital cable to a digital video recorder is more complex than analogSignals or digital signals. This is because the MPEG-2 or MPEG-4 stream is usually encrypted to pay people to view the content without having to (usually precludes subscription) a.
The satellite or cable set-top box does two things. First, decode the signal. Secondly, the flow of MPEG decoder in an analog, DVI or HDMI signal for viewing on TV. To connect the cable / satellite digital signals you must get the signal afterbe decrypted, but before it is decoded (between steps one and two), which is how DVRs built-in set-top boxes work.
Alternatively, it is that some satellite or (more commonly) cable set-top box, a FireWire port, which can be connected to a computer. The recorded MPEG stream can be transferred to the computer via the FireWire port, although it can be done live, is often used to transmit programs in a set-top box with DVR. (For information on this way on a popularSet-top boxes with DVR, please see the Wikibook entry How do I use a Motorola DVR, and some of the ideas, which may also include other set-top boxes are considered good.)
DVD
Many DVD-based DVRs are equipped with two DVD drives or an additional internal hard drive mounted. Such an agreement may be used to add the contents of a source DVD, which is not permitted to copy, the United States with the Digital Millennium Copyright Act, if the disk is encrypted. Most of these video streams DVR will therefore not recordencrypted movie discs.
camcorders
Some DVD-based DVRs incorporate a Firewire connector which are used to enable them to acquire digital video from a MiniDV or Digital 8 camcorder, possibly recording a simple DVD camcorder, how to play. Some transformation resulting DVD is usually possible, such as adding chapter points.
Security Applications
Digital video recorders configured for physical securityApplications to record video signals from CCTV cameras for detection and documentation. Many are designed for recording audio. DVRs have evolved into devices that are rich in game and in addition to providing services that the mere recording of video images that previously was done by video. A DVR CCTV system provides a variety of advanced features through the VCR technology including video-search by event, time, date and camera. There is also much more control overQuality and frame rate allowing disk space requirements and optimize the DVR can also be set to override the safety of her debut album, the hard disk is full. In some DVR security systems remote access to the records of security for a PC can also be achieved by connecting the recorder to a LAN or the Internet.
Security DVR can be either embedded or as a PC-based categories. A PC-based DVR architecture is a classical personal computer with video capture cards designed for Video frames to record. An embedded type DVR is a digital video recorder with its operating system and application software contained in firmware or read only memory developed.
Hardware Features
Hardware features of DVR security vary between manufacturers and may include, but are not necessarily limited to:
Designed for rack-mount or desktop configurations.
Single or video inputs with connector types consistent with the similar or> Digital video, provided that the coaxial cable, twisted pair or fiber optic cable. The most common number of inputs 1, 4, 8, 16 and 32 may be configured with a very large number of inputs or by bus through the networking of individuals with DVR.
Looping video outputs for each input, the corresponding video signal input and duplicates Connector. These output signals are used by other devices such as video matrixes, multiplexers, monitors, and video.
ControlledVideo outputs for external display.
Switches and indicators with which to control the various functions of the machine.
Network connections established according to the type of network, and to control the functions of the recorder and to send and / or receive video signals.
Connections to external control devices such as keyboards.
A connection to external pan-tilt-zoom drives that the position of cameras.
Internal CD, DVD, VCR devices typically for archiving video book.
Connections to external storage devices.
Alarm event inputs from external security detection devices, usually a time for each video input.
Outputs alarm event from internal detection features such as motion detection or loss of video data.
Software Features
Software features vary between manufacturers and may include, but are not necessarily limited to:
User selectable image capture rate or in the form all the input or the input of basic input. The function of capture rate canprogrammed to automatically adjust the speed of acquisition of the occurrence of an external alarm or an event internal
The resolution of images is based on all the input or the input of basic input. The function of image resolution can be programmed to automatically adjust the image resolution when an external alarm or an event procedure.
Motion Detection: a basic input for input, this feature detects motion detection in the entire image or user-defined portion ofImage and provides the sensitivity are usually used. Identifying causes of internal events to be output to allow external devices and / or be used to trigger changes in other internal functions.
Lack of motion detection. On a basic input for input, this feature detects the movement of an object in the field of view and the rest for another time you define. Identifying causes of internal events to be output to external devices and / or used to be able to trigger changes in other internalFeatures.
Direction of motion detection. On a basic input for input, this function detects the direction of motion in the image, which determined by the user, as unacceptable. Identifying causes of internal events to be output to allow external devices and / or be used to trigger changes in other internal functions.
Routing video input, video monitors on user input or automatic alerts or events.
Entry, date and time.
Alarm and EventRegister with the appropriate video inputs.
In an attempt to alarm and event.
One or more channels of audio recording.
Archivist.
remote control.
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