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a sound recording process that converts audio or analogue signals into a series of pulses that correspond to the voltage level. These can be stored on tape or on any other memory system
digital recording[′dij·əd·əl ri′kȯrd·iŋ]
Magnetic recording in which the information is first coded in a digital form, generally with a binary code that uses two discrete values of residual flux.
digital video(1) See DV.
(2) Video recording in digital form. In order to edit video in the computer or to embed video clips into multimedia documents, a video source must originate from a digital camera or be converted to digital. Frames from analog video cameras and VCRs are converted into digital frames (bitmaps) using frame grabbers or similar devices attached to a computer.
Uncompressed digital video signals require huge amounts of storage, and high-ratio real-time compression schemes, such as MPEG, are essential for handling digital video in today's computers. See D1, MPEG, DVD, digital nonlinear editing and DTV.
DIGITAL AND ANALOG INTERFACESDigital AnalogVideo Video DVI composite video HDMI component video SDIDigital AnalogAudio Audio S/PDIF analog audio TOSLINK
DVR(1) (Digital Video Recorder) A device that records video from up to a dozen or more surveillance cameras onto a hard disk. The frame rate can be switched from real time to time lapse in order to save storage space. Digital recorders are more flexible than earlier analog VHS tape systems, and the video can be easily transmitted over a computer network. See CCTV.
(2) (Digital Video Recorder) Also known as a "personal video recorder" (PVR) or "hard disk recorder," a DVR is a consumer device that allows the viewer to pause and rewind any broadcast, cable or satellite TV program as well as record and play back selected programs (see live pause). An order of magnitude more flexible than earlier videocassette tape recorders (VCRs), an entire season of programs from one or more favorite series can be recorded.
DVRs may be built into the set-top box or replace the box using plug-in modules (see CableCARD). They store incoming digital TV signals on the hard disk as well as digitize analog TV into the MPEG-2 format. The video may be compressed to maximize storage space.
Part of the Service or Stand-Alone
The DVR periodically downloads channel program guide updates as well as software updates for the unit itself. When the DVR is integrated into the cable or satellite set-top box, the downloads ride the same medium as the TV service. When the DVR is stand-alone, the downloads come in via the home network.
Before the Turn of the Century
DVRs first came on the market in 1999 with products from ReplayTV and TiVo (www.tivo.com). They quickly made the VCR obsolete for timeshifting TV programs, and Tivo became the DVR leader. ReplayTV was later acquired by SONICblue, D&M Holdings and eventually the DirecTV satellite TV service (www.directv.com). See cloud DVR, multi-room DVR sharing, live pause, DVD recorder and networked DVR. Contrast with NVR.
|This earlier DVR from ReplayTV appears in front of the Find Shows screen, which enables a viewer to search for programming throughout the week by keyword. (Image courtesy of ReplayTV.)|
magnetic recordingPlacing information (data, voice, video, etc.) on a ferromagnetic storage medium. See magnetic storage and ferromagnetic.
nonlinear video editingEditing video in the computer. Also called "nonlinear editing" (NLE), digital nonlinear systems provide high-quality post-production editing on a desktop computer. However, some detail may be lost if lossy compression is used to store the images (see lossy compression).
Prior to editing in the computer, a system using several analog tape decks was considered nonlinear video editing. Editing in digital is considerably easier.
If the video is used for electronic publishing on CDs, DVDs or the Web, after editing, the digital output is converted to any of several digital video formats.
Faster Movie Editing
If the video is a movie that was shot in film (analog), it is converted to digital to save time and money. The digital movie is edited, and when completed, the output is turned into an edit decision list (EDL). The EDL contains analog frame sources and time codes so that the original analog film can be quickly cut and spliced in the editing room, which costs several hundred dollars per hour.
From Analog to Digital to Analog
In order to produce today's graphics-intensive movies, the original analog film may be scanned at high resolution and converted to digital. The enhancements and animations are added to the original scenes in the computer, and the final output is converted back into analog film. This "digital intermediate" method allows myriad special effects to be added that would be extremely time consuming, if not impossible, in the analog domain.
A Wide Range of Prices
Nonlinear editing systems run the gamut from free software that works with video files already in the computer to add-in boards that support a variety of video inputs and outputs to stand-alone systems that cost tens of thousands of dollars. See linear video editing.