Digital Video Recorder

Posted in Uncategorized | February 27th, 2010

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 media. The term includes stand-alone set-top boxes and software for personal computers, video recording and playback to and from the disk allows.

History

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The DVR was first testedJuly 8, 1965, CBS, in which to explore the possibilities of the moment, freeze frame and rewind for broadcasts of sporting events. Ampex released the first commercial hard disk video recorder in 1967. HS-100 analog video recorded on a digital hard drive and can store up to 30 seconds.

Hard drive-based DVR
The first two consumer DVR, ReplayTV and TiVo, was the 1999 Consumer Electronics Show in Las Vegas, has been launched. Although ReplayTV won the "Best of Show"Video category, it was TiVo, which had gone to far greater commercial success. The units have gradually developed complementary abilities, such as DVD recording, commercial skip, sharing of recordings over the Internet, and the programming and control options remotely via handheld devices, network computers or Web browsers.

This makes the transition "time" feature (traditionally done by a VCR) much more convenient and also allows for "trick modes" such as Pause Live TV, instant replay ofInteresting scenes, skipping advertising. Most DVRs use the MPEG format for encoding analog video signals.

The two consumer DVR brands on U.S. DNNA TiVo and ReplayTV's. In the United Kingdom, TiVo has a small presence, Thomson, Topfield, Fusion, Pace and Humax also supply digital terrestrial television (DTT) DVRs. BSkyB markets a popular combined EPG and DVR as Sky +. Afrikaans South Africa-based MTN Satellite joy recently started their PVR which is available on their DSTVplatform.

Many satellite and cable companies are incorporating DVR functions into their set-top box, directive, DishPlayer / DishDVR, Scientific Atlanta Explorer 8xxx, Motorola 6xxx from Comcast, Moxi Media Center Dige (available through Charter, Adelphia, Sunflower , Bend Broadband, and soon Comcast and other cable companies), or Sky +. In this case there is no need for coding the DVR, such as the satellite signal is already a digitally encoded MPEG stream. DVR simplystores the digital stream directly to hard disk. In view of the broadcasters involved (grants), the design of the DVR-and directly recording encrypted digital stream, leading to features like the ability to use interactive TV recorded shows, pre-loaded programs. But it can also force manufacturers to not publish your photo and skippable revocation for implementation.

The software is available for transferring programs recorded on DVR or hardwarePC (eg, TiVoToGo and DVArchive).
PC
Software and hardware is available for personal computers running Microsoft Windows, Linux and Mac PVR to rotate, and is a popular choice for home theater PC (HTPC) enthusiasts.
Linux
There are many open source and GPL DVR applications for Linux:
MythTV
Freevo
DVR
VDR
KnoppMyth – provides an out of the box MythTV based PVR solution

Commercial version for Linux availableSageTV based on Gentoo Linux. Brightbox, a consumer electronics device using SageTV.

Macintosh
Elgato makes a series of DVR devices called EyeTV (400 / 500 / DTT, etc.). The software that comes with each unit (but available separately), also called EyeTV. Elgato's latest version 2.3 of EyeTV software that comes with a redesigned interface, better program guide (built in the program) and a "One Click" to feature video iPod. Miles DVR also makes the hardware raceEyeTV software, DVR devices that use other programs.

Other products include DVR myTV.PVR from EskapeLabs and ConvertX PVR from Plextor. MythTV (see above) also runs under OS X, but most boxes "are currently only supported under Linux. Precompiled binaries are available for MythTV front end, so a Mac to watch video from (and control) of a MythTV server running under Linux.

Apple provides applications software developer kit provides FireWireany Macintosh with a FireWire port to record the MPEG2 transport stream from a FireWire equipped cable box (for example Motorola 62xx, including HD streams). Applications may also be cable channels via the FireWire port change. Only the channels of transmission may be the rest of the registered channels are encrypted. iRecord is a free scheduled-recording program from the SDK.
Panels
Microsoft Windows has several free DVR applications, including GB-PVR, Got all mediaMediaPortal. DScaler has DVR support in the work.
There are also several specific applications, such as SageTV, SnapStream Beyond TV, ChrisTV, ShowShifter, Meedio (now a dead product – Yahoo! Buy more of its technology, and discontinued the line Meedio, and the repositioning of the software, Yahoo Go — TV, now a free product), InterVideo WinDVR, RECORDIT Plus and the R5000-HD.

There is also a separate version of Windows called Windows XP Media Center Editionhas the ability to DVR.

And for Microsoft Windows Vista in its standard functionality of Media Center.

Source Menu
TV and video is the term 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 modulated on a carrier frequency (ie a channel), so that multiple frequencies (ie, morechannels), at the same time can be received.
Analog TV
Analog television in NTSC, PAL and SECAM formats, analog cable, or regular VHS tapes use a signal directly to the electron beam is fed into the TV. There are a number of details about how this is done, but in essence each line in each frame corresponds to a certain fraction of time before the signal.

To record an analog signal a few steps are needed. A TV tuner card numbers in a certainfrequency and then functions as a frame grabber, breaking the rules of individual pixels and the quantization in a format that a computer can understand. Then series of frames, along with the sound (also sampled and quantized) are compressed into a manageable format, like MPEG-2, or WMF, usually in software. Some TV tuner cards such as TiVo or chip DVR-250/350 delivers an MPEG-2 or other compressed stream directly to the computer that is running both the frame and handle the pressuresilica. This reduces the load on the CPU provides a run, less expensive.

Analog broadcast copy protection
Many mass-produced consumer DVRs implement a copy protection system called CGMS-A (Copy Generation Management System – Analog). This code a couple of bits in the VBI of the analog video signal to clarify that one of the following statements:
Copying is freely permitted
You may not copy
A single copy of this material may be
This is a copyonly one copy of the materials were allowed to happen, so no further copies are allowed.

CGMS-A information may be present in analog television signals and preserved when the signal is recorded and played back by analog VCRs, which of course is not defined in pieces do not understand. But the restrictions still in force when you try to please the band on a reader.

Digital TV
Digital TV is the audio / visual emitted during theair in a digital format rather than analog. Recording digital TV is generally a simple record of MPEG-2 binary data received. No expensive hardware is required to quantize and compress the signal (as the broadcaster has already done in this study). MythTV DVR supports both international DVB signals and American ATSC signals while the HDTV Tivo only supports ATSC signals. In the United States, the FCC attempt at a road block on his DVR digital"Broadcast flag" regulation. Digital video recording, which has not won prior approval from the FCC for implementing "effective" digital rights management would be banned from interstate commerce since July 2005. The regulation was killed May 6, 2005.

DVD-based PVRs available on the market in 2006 is not able to capture the full extent of the visual signal available with high-definition television (HDTV). This is largely because HDTV standards were finalized inlater as the standard for DVDs. However, DVD-based PVRs can still be used (albeit at reduced visual quality) with HDTV HDTV is also available as a set of connectivity standard I / V.

Satellite or digital cable
Recording signals via satellite or digital cable to a digital video recorder is more complex than recording analog signals and digital signals. This is because MPEG-2 or MPEG-4 stream is usually encrypted to prevent people from readingcontent without having to pay for it (usually by subscription).

Satellite or cable set-top box does two things. First, it decodes the signal. In the second stream in an MPEG decoding analog, DVI or HDMI signal for viewing on television. In order to record cable / satellite digital signals you must get the signal after it has been decrypted, but before is decoded (between steps one and two), this is how DVRs built into set-top boxes work.

A possible alternative is that a number of satellites(more commonly) cable set-top boxes have a FireWire port to a computer can be connected. The recorded MPEG stream can be transmitted to the computer via the FireWire port, although it can be done live, it is more commonly used to transfer shows from one set-top box with DVR. (For instructions on how to make a popular set-top box with DVR, please see the Wikibook entry How to get a Motorola DVR use some of the ideas might apply to other set-top boxwell.)

DVD
Many DVD-based DVRs are equipped with two DVD players, or a second internal hard drive. This system can be used to bring content from a source DVD, which has not allowed the United States under the Digital Millennium Copyright Act, if the disk is encrypted. Most DVR which will not allow the recording of video streams from encrypted movie discs.

Camcorders
Some DVD-based DVRs incorporate a FireWire connector, which can be used to capture digitalvideo from a MiniDV or Digital 8 camcorder, possibly recording a simple DVD as the camcorder is played. Some editing of the resulting DVD is usually possible, such as adding chapter points.

Insurance Program
Digital video recording is set for physical security applications record video signals from a closed television cameras for detection and documentation purposes. Many of them were designed for a good sound. DVR evolved into entities that function isrich and the services that the simple recording of video images that were previously done through VCRs exceeded. DVR CCTV system provides a wide range of advanced features for the VCR technology including video searches by event, date, time and camera. There is also much more control on quality and frame rate of disk space used optimally, and the DVR can be set to overwrite the oldest security footage should the disk become full. In some DVR security systems remote accesssafety equipment with a computer, DVR can also connect to a LAN or the Internet must be achieved.

Security DVRs may be based on PC or embedded can not be classified. A PC-based DVR architecture is a standard personal computer with a video capture card designed for capturing video images. An embedded type DVR is specifically designed as a digital video recorder with an operating system and application software contained in firmware or read the broth.

HardwareFeatures
DVR hardware security features vary between manufacturers and may include, but are not necessarily limited to:
Designed for desktop or rack configurations.
One or more video inputs with connector types are compatible with analog or digital video provided as coaxial cable, twisted pair or fiber optic cable. The most common number of inputs are 1, 4, 8, 16 and 32 systems can be configured with a wide range of input from the network orEach DVR bus together.
Looping video outputs for each input, which plays the corresponding video signal input and the type of connector. These output signals from other video equipment that is used as a switch matrix, multiplexer, and video screens.
Controlled outputs to external monitors display video.
Front panel switches and indicators that the various features of the device to be controlled.
Hotspots based on the type of network and usedcontrol functions of the recorder and to send and / or video signals received.
Relations with external control devices such as keyboards.
A connection to external pan-tilt-zoom drives, cameras position.
Internal CD, DVD, VCR equipment, typically for archiving video.
Connections to external storage media.
Alarm event inputs from external security detection devices, usually one for each video input.
Outputs alarm event from internal detection features such as motion detection or loss ofvideo.

Software Features
Software features vary between manufacturers and may include, but are not necessarily limited to:
User selects the image acquisition is based on all fares input or input-based input. The function of consumption rate can be programmed to automatically adjust the speed to capture the appearance of an external alarm or an event internal
Selectable image resolution, both in the foundations of input or input-based input. Function Image Resolutionprogrammed to automatically adjust the image resolution on the presence of an external alarm or an event procedure.
Motion: By clicking an entry of basic input, this feature detects motion in the entire image or user definieërbare part of the image, and typically provide a sensitivity settings. Identifying causes of internal events that can lead to external devices and / or used to trigger changes in other internal functions.
The lack of movement. GivingInput from the basic input for this function, the proposal for an object in the visual field, and the rest, even for a user definieërbare time. Identifying causes of internal events that can lead to external devices and / or used to trigger changes in other internal functions.
Direction of motion. Give a basic input entry of this function assumes the direction of motion in the picture, as defined by the user as an unacceptable incident. Detection causes an internalwhich can lead to external devices and / or used to trigger changes in other internal functions.
Routing input from video to video displays based on user input or automatically on events or alarms.
Inputs, time and date stamp.
Alarm and event log on the appropriate video input.
Alarm and search events.
One or more audio channels.
Archiving.
Remote control.

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