Information about Digital Video
Digital video is a type of video recording system that works by using a digital, rather than analog, of the video signal.
The terms camera, video camera, and camcorder are used interchangeably in this article.
Early experiments with digital video were first accomplished throughout the 1960s by the research departments of entities such as the BBC and Bell Laboratories, both developing such to eliminate the introduction of noise and distortion on video feeds for television sent over the terrestrial microwave relay and coaxial cable circuits of the day.
Also starting in the late 70s to the early 80s, several types of video production equipment, such as time base correctors (TBC) and digital video effects (DVE) units (two of the latter being the Ampex ADO, and the NEC DVE), were introduced that would operate by taking a standard analog video input and internally digitizing it. This made it easier to either correct or enhance the video signal, as in the case of a TBC, or to manipulate and add effects to the video, in the case of a DVE unit. The digitized and processed video from these units would then be converted back to standard analog video.
Later on in the 1970s, manufacturers of professional video broadcast equipment, such as Bosch (through their Fernseh division), RCA, and Ampex developed prototype digital videotape recorders in their research and development labs. Bosch's machine used a modified 1" Type B transport, and recorded an early form of CCIR 601 digital video. None of these machines from these manufacturers were ever marketed commercially, however.
Digital video was first introduced commercially in 1986 with the Sony D-1 format, which recorded an uncompressed standard definition component video signal in digital form instead of the high-band analog forms that had been commonplace until then. Due to the expense, D-1 was used primarily by large television networks. It would eventually be replaced by cheaper systems using compressed data, most notably Sony's Digital Betacam, still heavily used as a field recording format by professional television producers.
Consumer digital video first appeared in the form of QuickTime, Apple Computer's architecture for time-based and streaming data formats, which appeared in crude form around 1990. Initial consumer-level content creation tools were crude, requiring an analog video source to be digitized to a computer-readable format. While low-quality at first, consumer digital video increased rapidly in quality, first with the introduction of playback standards such as MPEG-1 and MPEG-2 (adopted for use in television transmission and DVD media), and then the introduction of the DV tape format allowing recording direct to digital data and simplifying the editing process, allowing non-linear editing systems to be deployed wholly on desktop computers.
A progressive scanning digital video camera records each frame as distinct, with both fields being identical. Thus, interlaced video captures twice as many fields per second as progressive video does when both operate at the same number of frames per second. This is one of the reasons video has a “hyper-real” look, because it draws a different image 60 times per second, as opposed to film, which records 24 or 25 progressive frames per second.
Progressive scan camcorders such as the Panasonic DVX100 are generally more desirable because of the similarities they share with film. They both record frames progressively, which results in a crisper image. They can both shoot at 24 frames per second, which results in motion strobing (blurring of the subject when fast movement occurs). Thus, progressive scanning video cameras tend to be more expensive than their interlaced counterparts. (Note that even though the digital video format only allows for 29.97 interlaced frames per second [or 25 for PAL], 24 frames per second progressive video is possible by displaying identical fields for each frame, and displaying 3 fields of an identical image for certain frames. For a more detailed explanation, see the adamwilt.com link.)
Standard film stocks such as 16 mm and 35 mm record at 24 or 25 frames per second. For video, there are two frame rate standards: NTSC, and PAL, which shoot at 30/1.001 (about 29.97) frames per second and 25 frames per second, respectively.
Digital video can be copied with no degradation in quality. No matter how many generations a digital source is copied, it will be as clear as the original first generation of digital footage.
Digital video can be processed and edited on an NLE, or non-linear editing station, a device built exclusively to edit video and audio. These frequently can import from analog as well as digital sources, but are not intended to do anything other than edit videos. Digital video can also be edited on a personal computer which has the proper hardware and software. Using a NLE station, digital video can be manipulated to follow an order, or sequence, of video clips. Avid's software and hardware is almost synonymous with the professional NLE market, but Apple’s Final Cut Pro, Adobe Premiere, Sony Vegas and similar programs are also popular.
More and more, videos are edited on readily available, increasingly affordable hardware and software. Even large budget films, such as Cold Mountain, have been edited entirely on Final Cut Pro, Apple's non linear editing software.
Regardless of software, digital video is generally edited on a setup with ample disk space. Digital video applied with standard DV/DVCPRO compression takes up about 250 megabytes per minute or 13 gigabytes per hour.
Digital video has a significantly lower cost than 35 mm film, as the digital tapes can be erased and re-recorded multiple times, viewed on location without processing, and the tape stock itself is very inexpensive (about $3 for a 60 minute MiniDV tape, in bulk, as of December, 2005). By comparison, 35 mm film stock costs about $1000 per minute, including processing.
Digital video is used outside of movie making. Digital television (including higher quality HDTV) started to spread in most developed countries in early 2000s. Digital video is also used in modern mobile phones and video conferencing systems. Digital video is also used for Internet distribution of media, including streaming video and peer-to-peer movie distribution.
Many types of video compression exist for serving digital video over the internet, and onto DVDs. Although digital technique allows for a wide variety of edit effects, most common is the hard cut and an editable video format like DV-video allows repeated cutting without loss of quality, because any compression across frames is lossless. While DV video is not compressed beyond its own codec while editing, the file sizes that result are not practical for delivery onto optical discs or over the internet, with codecs such as the Windows Media format, MPEG2, MPEG4, Real Media, the more recent H.264, and the Sorenson media codec. Probably the most widely used formats for delivering video over the internet are MPEG4 and Windows Media, while MPEG2 is used almost exclusively for DVDs, providing an exceptional image in minimal size but resulting in a high level of CPU consumption to decompress.
While still images can have any number of pixels the video community defines one standard for resolution after the other and notwithstanding the devices use incompatible resolutions and insist on their resolution and rescale a video several times from the sensor to the LCD. Anamorph still images are the result of technical limitations while anamorph videos can be result of standardization aberrations. As of 2007, the highest resolution demonstrated for digital video generation is 33 megapixels (7680 x 4320) at 60 frames per second ("UHDV"), though this has only been demonstrated in special laboratory settings. The highest speed is attained in industrial and scientific high speed cameras that are capable of filming 1024x1024 video at up to 1 million frames per second for brief periods of recording.
Early experiments with digital video were first accomplished throughout the 1960s by the research departments of entities such as the BBC and Bell Laboratories, both developing such to eliminate the introduction of noise and distortion on video feeds for television sent over the terrestrial microwave relay and coaxial cable circuits of the day.
Also starting in the late 70s to the early 80s, several types of video production equipment, such as time base correctors (TBC) and digital video effects (DVE) units (two of the latter being the Ampex ADO, and the NEC DVE), were introduced that would operate by taking a standard analog video input and internally digitizing it. This made it easier to either correct or enhance the video signal, as in the case of a TBC, or to manipulate and add effects to the video, in the case of a DVE unit. The digitized and processed video from these units would then be converted back to standard analog video.
Later on in the 1970s, manufacturers of professional video broadcast equipment, such as Bosch (through their Fernseh division), RCA, and Ampex developed prototype digital videotape recorders in their research and development labs. Bosch's machine used a modified 1" Type B transport, and recorded an early form of CCIR 601 digital video. None of these machines from these manufacturers were ever marketed commercially, however.
Digital video was first introduced commercially in 1986 with the Sony D-1 format, which recorded an uncompressed standard definition component video signal in digital form instead of the high-band analog forms that had been commonplace until then. Due to the expense, D-1 was used primarily by large television networks. It would eventually be replaced by cheaper systems using compressed data, most notably Sony's Digital Betacam, still heavily used as a field recording format by professional television producers.
Consumer digital video first appeared in the form of QuickTime, Apple Computer's architecture for time-based and streaming data formats, which appeared in crude form around 1990. Initial consumer-level content creation tools were crude, requiring an analog video source to be digitized to a computer-readable format. While low-quality at first, consumer digital video increased rapidly in quality, first with the introduction of playback standards such as MPEG-1 and MPEG-2 (adopted for use in television transmission and DVD media), and then the introduction of the DV tape format allowing recording direct to digital data and simplifying the editing process, allowing non-linear editing systems to be deployed wholly on desktop computers.
Technical overview
Digital video cameras come in two different image capture formats: interlaced and progressive scan. Interlaced cameras record the image in alternating sets of lines: the odd-numbered lines are scanned, and then the even-numbered lines are scanned, then the odd-numbered lines are scanned again, and so on. One set of odd or even lines is referred to as a "field", and a consecutive pairing of two fields of opposite parity is called a frame.A progressive scanning digital video camera records each frame as distinct, with both fields being identical. Thus, interlaced video captures twice as many fields per second as progressive video does when both operate at the same number of frames per second. This is one of the reasons video has a “hyper-real” look, because it draws a different image 60 times per second, as opposed to film, which records 24 or 25 progressive frames per second.
Progressive scan camcorders such as the Panasonic DVX100 are generally more desirable because of the similarities they share with film. They both record frames progressively, which results in a crisper image. They can both shoot at 24 frames per second, which results in motion strobing (blurring of the subject when fast movement occurs). Thus, progressive scanning video cameras tend to be more expensive than their interlaced counterparts. (Note that even though the digital video format only allows for 29.97 interlaced frames per second [or 25 for PAL], 24 frames per second progressive video is possible by displaying identical fields for each frame, and displaying 3 fields of an identical image for certain frames. For a more detailed explanation, see the adamwilt.com link.)
Standard film stocks such as 16 mm and 35 mm record at 24 or 25 frames per second. For video, there are two frame rate standards: NTSC, and PAL, which shoot at 30/1.001 (about 29.97) frames per second and 25 frames per second, respectively.
Digital video can be copied with no degradation in quality. No matter how many generations a digital source is copied, it will be as clear as the original first generation of digital footage.
Digital video can be processed and edited on an NLE, or non-linear editing station, a device built exclusively to edit video and audio. These frequently can import from analog as well as digital sources, but are not intended to do anything other than edit videos. Digital video can also be edited on a personal computer which has the proper hardware and software. Using a NLE station, digital video can be manipulated to follow an order, or sequence, of video clips. Avid's software and hardware is almost synonymous with the professional NLE market, but Apple’s Final Cut Pro, Adobe Premiere, Sony Vegas and similar programs are also popular.
More and more, videos are edited on readily available, increasingly affordable hardware and software. Even large budget films, such as Cold Mountain, have been edited entirely on Final Cut Pro, Apple's non linear editing software.
Regardless of software, digital video is generally edited on a setup with ample disk space. Digital video applied with standard DV/DVCPRO compression takes up about 250 megabytes per minute or 13 gigabytes per hour.
Digital video has a significantly lower cost than 35 mm film, as the digital tapes can be erased and re-recorded multiple times, viewed on location without processing, and the tape stock itself is very inexpensive (about $3 for a 60 minute MiniDV tape, in bulk, as of December, 2005). By comparison, 35 mm film stock costs about $1000 per minute, including processing.
Digital video is used outside of movie making. Digital television (including higher quality HDTV) started to spread in most developed countries in early 2000s. Digital video is also used in modern mobile phones and video conferencing systems. Digital video is also used for Internet distribution of media, including streaming video and peer-to-peer movie distribution.
Many types of video compression exist for serving digital video over the internet, and onto DVDs. Although digital technique allows for a wide variety of edit effects, most common is the hard cut and an editable video format like DV-video allows repeated cutting without loss of quality, because any compression across frames is lossless. While DV video is not compressed beyond its own codec while editing, the file sizes that result are not practical for delivery onto optical discs or over the internet, with codecs such as the Windows Media format, MPEG2, MPEG4, Real Media, the more recent H.264, and the Sorenson media codec. Probably the most widely used formats for delivering video over the internet are MPEG4 and Windows Media, while MPEG2 is used almost exclusively for DVDs, providing an exceptional image in minimal size but resulting in a high level of CPU consumption to decompress.
While still images can have any number of pixels the video community defines one standard for resolution after the other and notwithstanding the devices use incompatible resolutions and insist on their resolution and rescale a video several times from the sensor to the LCD. Anamorph still images are the result of technical limitations while anamorph videos can be result of standardization aberrations. As of 2007, the highest resolution demonstrated for digital video generation is 33 megapixels (7680 x 4320) at 60 frames per second ("UHDV"), though this has only been demonstrated in special laboratory settings. The highest speed is attained in industrial and scientific high speed cameras that are capable of filming 1024x1024 video at up to 1 million frames per second for brief periods of recording.
Interfaces and cables
Many interfaces have been designed specifically to handle the requirements of uncompressed digital video (at roughly 400 Mbit/s):- Serial Digital Interface
- FireWire
- High-Definition Multimedia Interface
- Digital Visual Interface
- Unified Display Interface
- DisplayPort
- USB
- Using RTP as a wrapper for video packets
- 1-7 MPEG Transport Packets are placed directly in the UDP packet
Storage formats
Encoding
All current formats, which are listed below, are PCM based.- CCIR 601 used for broadcast stations
- MPEG-4 good for online distribution of large videos and video recorded to flash memory
- MPEG-2 used for DVDs and Super-VCDs
- MPEG-1 used for video CDs
- H.261
- H.263
- H.264 also known as MPEG-4 Part 10, or as AVC
- Theora standardized but still in development. used for video over the internet.
Tapes
- Betacam, BetacamSP, Betacam SX, Betacam IMX, Digital Betacam, or DigiBeta — Commercial video systems by Sony, based on original Betamax technology
- D1, D2, D3, D5, D9 (also known as Digital-S) — various SMPTE commercial digital video standards
- DV, MiniDV — used in most of today's videotape-based consumer camcorders; designed for high quality and easy editing; can also record high-definition data (HDV) in MPEG-2 format
- DVCAM, DVCPRO — used in professional broadcast operations; similar to DV but generally considered more robust; though DV-compatible, these formats have better audio handling
- Digital8 — DV-format data recorded on Hi8-compatible cassettes; largely a consumer format
- MicroMV — MPEG-2-format data recorded on a very small, matchbook-sized cassette; obsolete
- D-VHS — MPEG-2 format data recorded on a tape similar to S-VHS
Discs
- Video CD (VCD)
- DVD
- HD-DVD
- Blu-ray Disc
- Sony ProDATA
See also
- Digital audio
- Digital cinematography
- Digital film
- Digital visual interface
- DVD
- HDV
- ProHD
- AVCHD
- HD video
- Camcorder and Tapeless camcorder
- List of video topics
- Online media center
- Television
- Video
- Video coding
- Video editing software
- Video sharing
- Webcam
External links
- http://www.digitalvideobusiness.com/DigitalVideoBusiness - Emerging News For Internet Rich Media - Free Subscription
- Digital Video magazine
- The DV Show - Podcasting the Ins and Outs of Digital Video
- IzzyVideo.com - Watch a Video Podcast about shooting better Digital Video
- Adam Wilt's website, including the DV FAQ
- Adam Wilt's explanation of how 24 progressive frames per second video is recorded to 29.97 interlaced frames per second
- Home Video101 - Contains non vendor specific information for creating DVDs from home movies.
| Digital systems |
|---|
| Logic gate | digital circuit | integrated circuit (IC) |
| Theory — boolean logic | digital signal processing | computer architecture |
| Applications — digital photography | digital audio | digital video |
Industrial & home video media | |||
|---|---|---|---|
| Magnetic tape |
| ||
| Optical disc |
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| Grooved Videodiscs |
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Video (Latin for "I see", first person singular present, indicative of videre, "to see") is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.
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A digital system is one that uses discrete values (often electrical voltages), representing numbers or non-numeric symbols such as letters or icons, for input, processing, transmission, storage, or display, rather than a continuous range of values (ie, as in an analog system).
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An analog or analogue signal is any time continuous signal where some time varying feature of the signal is a representation of some other time varying quantity. It differs from a digital signal in that small fluctuations in the signal are meaningful.
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The British Broadcasting Corporation (BBC)
Type Broadcast radio and television
Country United Kingdom
Availability National
International
Founder John Reith
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Type Broadcast radio and television
Country United Kingdom
Availability National
International
Founder John Reith
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Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) is part of the research and development organization of Alcatel-Lucent and previously the United States Bell System.
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Time base correction is a technique to reduce or eliminate errors caused by mechanical instability present in analog recordings on mechanical media, including video tape recorders and videocassette recorders.
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NEC Corporation
Corporation TYO: 6701 , NASDAQ: NIPNY
Founded Tokyo, Japan (1899)
Headquarters Tokyo, Japan
Key people Hajime Sasaki, Chairman of the Board; Akinobu Kanasugi, Vice Chairman of the Board; Kaoru Yano, President
Industry Electronics
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Corporation TYO: 6701 , NASDAQ: NIPNY
Founded Tokyo, Japan (1899)
Headquarters Tokyo, Japan
Key people Hajime Sasaki, Chairman of the Board; Akinobu Kanasugi, Vice Chairman of the Board; Kaoru Yano, President
Industry Electronics
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Robert Bosch GmbH
GmbH
Founded 1886
Headquarters Gerlingen, Germany
Key people Robert Bosch, founder
Industry Automotive, Small appliance
Products Automotive parts, Power tools
Revenue $43,7 Billions (2006)
Net income $2,17 Billions (2006)
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GmbH
Founded 1886
Headquarters Gerlingen, Germany
Key people Robert Bosch, founder
Industry Automotive, Small appliance
Products Automotive parts, Power tools
Revenue $43,7 Billions (2006)
Net income $2,17 Billions (2006)
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The Fernseh AG television company was registered in Berlin on the 3rd July, 1929 by John Logie Baird, Robert Bosch and other partners[1] with an initial capital of 100,000 Reichsmark[2].
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RCA, formerly an acronym for the Radio Corporation of America, is now a trademark owned by Thomson SA through RCA Trademark Management S.A., a company owned by Thomson.
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AMPEX (NASDAQ: AMPX ) is an American electronics company founded in 1944. The name AMPEX is an acronym, created by its founder, Alexander M. Poniatoff, which stands for Alexander M. Poniatoff Excellence.
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The phrase research and development (also R and D or, more often, R&D), according to the Organization of Economic Cooperation and Development, refers to "creative work undertaken on a systematic basis in order to increase the stock of knowledge, including knowledge of
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1 inch type B VTR (designated Type B by SMPTE) is an open-reel videotape format developed by the Bosch Fernseh devision of Bosch in Germany in 1976. It never saw much success compared to the competing 1" Type C format, due to the format requiring an optional, and costly, digital
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CCIR 601 is the old name of a standard published by the CCIR (now ITU-R) for encoding interlaced analogue video signals in digital form. The new name of the standard is ITU-R BT.601, but the old name is still in common use in informal contexts.
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Sony Corporation
ソニー株式会?
Public (TYO: 6758 ; NYSE: SNE )
Founded May 7 1946 (adopted current name in 1958) by Masaru Ibuka and Akio Morita[1]
Headquarters Minato-ku, Tokyo, Japan[1]
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ソニー株式会?
Public (TYO: 6758 ; NYSE: SNE )
Founded May 7 1946 (adopted current name in 1958) by Masaru Ibuka and Akio Morita[1]
Headquarters Minato-ku, Tokyo, Japan[1]
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D-1 format was the first major professional digital video format, introduced in 1986 through efforts by SMPTE engineering committees.
D-1 stored uncompressed digitized component video, encoded at using the CCIR 601 raster format, along with PCM audio tracks as well as
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D-1 stored uncompressed digitized component video, encoded at using the CCIR 601 raster format, along with PCM audio tracks as well as
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Standard-definition television or SDTV refers to television systems that have a resolution that meets standards but not considered either enhanced definition or high definition.
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Component video is a video signal that has been split into two or more components. In popular use, it refers to a type of analog video information that is transmitted or stored as three separate signals.
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A television network is a distribution for television content whereby a central operation provides programming for many television stations. Until the mid-1980s, television programming in most countries of the world was dominated by a small number of broadcast networks.
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Betacam is a family of half-inch professional videotape products developed by Sony from 1982 onwards. In casual use, "Betacam" singly is often used to refer to a Betacam camcorder, a Betacam tape, or a Betacam video recorder.
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Maintainer: Apple Inc.
OS: Mac OS X, Windows XP and Vista
Use: Multimedia framework
License: Proprietary
Website: www.apple.com/quicktime/ QuickTime is a multimedia framework developed by Apple Inc.
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OS: Mac OS X, Windows XP and Vista
Use: Multimedia framework
License: Proprietary
Website: www.apple.com/quicktime/ QuickTime is a multimedia framework developed by Apple Inc.
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Apple Inc.
Public (NASDAQ: AAPL , LSE: ACP , FWB: APC )
Founded California (April 1 1976, as Apple Computer, Inc.)
Headquarters 1 Infinite Loop, Cupertino, California
Key people Steve Jobs, CEO & Co-founder
Steve Wozniak, Co-founder
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Public (NASDAQ: AAPL , LSE: ACP , FWB: APC )
Founded California (April 1 1976, as Apple Computer, Inc.)
Headquarters 1 Infinite Loop, Cupertino, California
Key people Steve Jobs, CEO & Co-founder
Steve Wozniak, Co-founder
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MPEG-1 defines a group of Audio and Video (AV) coding and compression standards agreed upon by MPEG (Moving Picture Experts Group). MPEG-1 video is used by the Video CD (VCD) format and less commonly by the DVD-Video format.
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MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information".[1] It describes a combination of lossy video compression and lossy audio compression (audio data compression) methods which permit storage and transmission of movies using
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DVD
Media type: Optical disc
Capacity: 4.7 GB (single layer), 8.5 GB (dual layer)
Usage: Data storage, audio, video, games
Optical disc authoring
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Media type: Optical disc
Capacity: 4.7 GB (single layer), 8.5 GB (dual layer)
Usage: Data storage, audio, video, games
Optical disc authoring
- Optical disc
- Optical disc image
- Recorder hardware
- Authoring software
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Digital Video (DV) is a digital video format launched in 1994, and, in its smaller tape form factor MiniDV, has since become a standard for home and semiprofessional video production; it is sometimes used for professional purposes as well, such as filmmaking and electronic
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non-linear editing system (NLE) is a video editing (NLVE) or audio editing (NLAE) system which can perform random access on the source material.
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Non-linear editing
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Interlace is a technique of improving the picture quality of a video signal without consuming any extra bandwidth. It was invented by RCA engineer Randall C. Ballard in the 1930s.
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Progressive or noninterlaced scanning is any method for displaying, storing or transmitting moving images in which all the lines of each frame are drawn in sequence.
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Frame rate, or frame frequency, is the measurement of the frequency (rate) at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems.
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This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.
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