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Digital video is a type of digital recording system that works by using a digital rather than an analog video signal.

The terms camera, video camera, and camcorder are used interchangeably in this article.

History[link]

Starting in the late 1970s to the early 1980s, several types of video production equipment were introduced, such as time base correctors (TBC) and digital video effects (DVE) units (one of the former being the Thomson-CSF 9100 Digital Video Processor, an internally all-digital full-frame TBC introduced in 1980, and two of the latter being the Ampex ADO, and the Nippon Electric Corporation (NEC) DVE). They operated by taking a standard analog composite video input and digitizing it internally. 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 information 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 (VTR) 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 its expense, D-1 was used primarily by large television networks. It would eventually be replaced by cheaper systems using video compression, most notably Sony's Digital Betacam (still heavily used as a electronic field production (EFP) recording format by professional television producers) that were introduced into the network's television studios.

One of the first digital video products to run on personal computers was PACo: The PICS Animation Compiler from The Company of Science & Art in Providence, RI, which was developed starting in 1990 and first shipped in May 1991.^[1] PACo could stream unlimited-length video with synchronized sound from a single file on CD-ROM. Creation required a Mac; playback was possible on Macs, PCs, and Sun Sparcstations. In 1992, Bernard Luskin, Philips Interactive Media, and Eric Doctorow, Paramount Worldwide Video, successfully put the first fifty videos in digital MPEG 1 on CD, developed the packaging and launched movies on CD, leading to advancing versions of MPEG, and to DVD.

QuickTime, Apple Computer's architecture for time-based and streaming data formats appeared in June, 1991. 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 (NLE) to be deployed cheaply and widely on desktop computers with no external playback/recording equipment needed. The widespread adoption of digital video has also drastically reduced the bandwidth needed for a high-definition video signal (with HDV and AVCHD, as well as several commercial variants such as DVCPRO-HD, all using less bandwidth than a standard definition analog signal) and tapeless camcorders based on flash memory and often a variant of MPEG-4.

Overview of basic properties[link]

Digital video comprises a series of orthogonal bitmap digital images displayed in rapid succession at a constant rate. In the context of video these images are called frames.^[2] We measure the rate at which frames are displayed in frames per second (FPS).

Since every frame is an orthogonal bitmap digital image it comprises a raster of pixels. If it has a width of W pixels and a height of H pixels we say that the frame size is WxH.

Pixels have only one property, their color. The color of a pixel is represented by a fixed number of bits. The more bits the more subtle variations of colors can be reproduced. This is called the color depth (CD) of the video.

An example video can have a duration (T) of 1 hour (3600sec), a frame size of 640x480 (WxH) at a color depth of 24bits and a frame rate of 25fps. This example video has the following properties:

• pixels per frame = 640 * 480 = 307,200
• bits per frame = 307,200 * 24 = 7,372,800 = 7.37Mbits
• bit rate (BR) = 7.37 * 25 = 184.25Mbits/sec
• video size (VS)^[3] = 184Mbits/sec * 3600sec = 662,400Mbits = 82,800Mbytes = 82.8Gbytes

The most important properties are bit rate and video size. The formulas relating those two with all other properties are:

BR = W * H * CD * FPS
VS = BR * T = W * H * CD * FPS * T
  (units are:  BR in bit/s,  W and H in pixels,  CD in bits,  VS in bits,  T in seconds)

while some secondary formulas are:

pixels_per_frame  = W * H
pixels_per_second = W * H * FPS
bits_per_frame    = W * H * CD

Regarding Interlacing[link]

In interlaced video each frame is composed of two halves of an image. The first half contains only the odd-numbered lines of a full frame. The second half contains only the even-numbered lines. Those halves are referred to individually as fields. Two consecutive fields compose a full frame. If an interlaced video has a frame rate of 15 frames per second the field rate is 30 fields per second. All the properties and formulas discussed here apply equally to interlaced video but one should be careful not to confuse the fields per second rate with the frames per second rate.

Properties of compressed video[link]

The above are accurate for uncompressed video. Because of the relatively high bit rate of uncompressed video, video compression is extensively used. In the case of compressed video each frame requires a small percentage of the original bits. Assuming a compression algorithm that shrinks the input data by a factor of CF, the bit rate and video size would equal to:

BR = W * H * CD * FPS / CF
VS = BR * T / CF

Please note that it is not necessary that all frames are equally compressed by a factor of CF. In practice they are not, so CF is the average factor of compression for all the frames taken together.

The above equation for the bit rate can be rewritten by combining the compression factor and the color depth like this:

BR = W * H * ( CD / CF ) * FPS

The value (CD / CF) represents the average bits per pixel (BPP). As an example, if we have a color depth of 12bits/pixel and an algorithm that compresses at 40x, then BPP equals 0.3 (12/40). So in the case of compressed video the formula for bit rate is:

BR = W * H * BPP * FPS

In fact the same formula is valid for uncompressed video because in that case one can assume that the "compression" factor is 1 and that the average bits per pixel equal the color depth.

More on bit rate and BPP[link]

As is obvious by its definition bit rate is a measure of the rate of information content of the digital video stream. In the case of uncompressed video, bit rate corresponds directly to the quality of the video (remember that bit rate is proportional to every property that affects the video quality). Bit rate is an important property when transmitting video because the transmission link must be capable of supporting that bit rate. Bit rate is also important when dealing with the storage of video because, as shown above, the video size is proportional to the bit rate and the duration. Bit rate of uncompressed video is too high for most practical applications. Video compression is used to greatly reduce the bit rate.

BPP is a measure of the efficiency of compression. A true-color video with no compression at all may have a BPP of 24 bits/pixel. Chroma subsampling can reduce the BPP to 16 or 12 bits/pixel. Applying jpeg compression on every frame can reduce the BPP to 8 or even 1 bits/pixel. Applying video compression algorithms like MPEG1, MPEG2 or MPEG4 allows for fractional BPP values.

Constant bit rate versus variable bit rate[link]

As noted above BPP represents the average bits per pixel. There are compression algorithms that keep the BPP almost constant throughout the entire duration of the video. In this case we also get video output with a constant bit rate (CBR). This CBR video is suitable for real-time, non-buffered, fixed bandwidth video streaming (e.g. in videoconferencing).

Noting that not all frames can be compressed at the same level because quality is more severely impacted for scenes of high complexity some algorithms try to constantly adjust the BPP. They keep it high while compressing complex scenes and low for less demanding scenes. This way one gets the best quality at the smallest average bit rate (and the smallest file size accordingly). Of course when using this method the bit rate is variable because it tracks the variations of the BPP.

Technical overview[link]

Standard film stocks such as 16 mm and 35 mm record at 24 frames per second. For video, there are two frame rate standards: NTSC, which shoot at 30/1.001 (about 29.97) frames per second or 59.94 fields per second, and PAL, 25 frames per second or 50 fields per second.

Digital video cameras come in two different image capture formats: interlaced and deinterlaced / 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. Deinterlaced cameras records each frame as distinct, with all scan lines being captured at the same moment in time. Thus, interlaced video captures samples the scene motion twice as often as progressive video does, for the same number of frames per second. Progressive-scan camcorders generally produce a slightly sharper image. However, motion may not be as smooth as interlaced video which uses 50 or 59.94 fields per second, particularly if they employ the 24 frames per second standard of film.

Digital video can be copied with no degradation in quality. No matter how many generations of a digital source is copied, it will still be as clear as the original first generation of digital footage. However a change in parameters like frame size as well as a change of the digital format can decrease the quality of the video due to new calculations that have to be made. Digital video can be manipulated and edited to follow an order or sequence on an NLE, or non-linear editing workstation, a computer-based device intended to edit video and audio. More and more, videos are edited on readily available, increasingly affordable consumer-grade computer hardware and software. However, such editing systems require ample disk space for video footage. The many video formats and parameters to be set make it quite impossible to come up with a specific number for how many minutes need how much time.

Digital video has a significantly lower cost than 35 mm film. The tape stock itself is very inexpensive. Digital video also allows footage to be viewed on location without the expensive chemical processing required by film. Also physical deliveries of tapes and broadcasts do not apply anymore. 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. However even within Europe are lots of TV-Stations not broadcasting in HD, due to restricted budgets for new equipment for processing HD.

Many types of video compression exist for serving digital video over the internet and on optical disks. The file sizes of digital video used for professional editing are generally not practical for these purposes, and the video requires further compression with codecs such as Sorenson, H264 and more recently AppleProRes especially for HD. Probably the most widely used formats for delivering video over the internet are MPEG4, Quicktime, Flash 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.

As of 2011^[update], the highest resolution demonstrated for digital video generation is 35 megapixels (8192 x 4320). 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.

Poster frame[link]

A poster frame or preview frame is a selected frame of the video used as a thumbnail.^[4]

Interfaces and cables[link]

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
• Digital component video

The following interface has been designed for carrying MPEG-Transport compressed video:

• DVB-ASI

Compressed video is also carried using UDP-IP over Ethernet. Two approaches exist for this:

• Using RTP as a wrapper for video packets
• 1-7 MPEG Transport Packets are placed directly in the UDP packet

Storage formats[link]

Encoding[link]

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, Super-VCDs, and many broadcast television formats
• MPEG-1 used for video CDs
• H.261
• H.263
• H.264 also known as MPEG-4 Part 10, or as AVC, used for Blu-ray Discs and some broadcast television formats
• Theora used for video on Wikipedia

Tapes[link]

• Betacam SX, Betacam IMX, Digital Betacam, or DigiBeta — Commercial video systems by Sony, based on original Betamax technology
• HDCAM was introduced by Sony as a high-definition alternative to DigiBeta.
• 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.
• DVCPRO50, DVCPROHD support higher bandwidths as compared to Panasonic's DVCPRO.
• 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[link]

• Blu-ray Disc
• DVD
• VCD

See also[link]

References[link]

1. ^ CoSA Lives: The Story of the Company Behind After Effects, http://www.motionworks.com.au/2009/11/cosa-lives/, retrieved 11/15/2009.
2. ^ In fact the still images correspond to frames only in the case of progressive scan video. In interlaced video they correspond to fields. See section about interlacing for clarification
3. ^ we use the term video size instead of just size in order to avoid confusion with the frame size
4. ^ Delivering a reliable Flash video experience, http://www.adobe.com/devnet/flash/articles/flash_cs3_video_techniques_ch12.pdf, retrieved 14/1/2010

plug inns

External links[link]

• The DV, DVCAM, & DVCPRO Formats -- tech details, FAQ, and links
• Standard digital TV and video formats.

Robert Norman "Bob" Ross (October 29, 1942 – July 4, 1995) was an American painter, art instructor, and television host.^[1] He is best known as the creator and host of The Joy of Painting, a television program that ran on PBS in the United States.

Personal life[link]

Ross was born in Daytona Beach, Florida, and attended school until the ninth grade.^[2] Raised in Orlando, Florida,^[3] Ross enlisted in the U.S. Air Force at age 18^[2] and was living in Florida early in his military career when the Air Force transferred him to Eielson AFB (in Alaska), where he first saw the snow and mountains that later became recurring themes in his artwork; he developed his quick-painting technique in order to be able to create art for sale in brief daily work breaks.^[4] Having held military positions that required him to be, in his own words, "mean" and "tough," "the guy who makes you scrub the latrine, the guy who makes you make your bed, the guy who screams at you for being late to work," Ross decided that if he ever moved on from the military, "it wasn't going to be that way any more," "vowing never to scream again".^[4] Ross discovered after beginning his sideline in painting that he was soon able to earn more from selling his work than from his Air Force position. After leaving the Air Force, he studied with Bill Alexander before becoming famous worldwide with his own television program, The Joy of Painting.^[1]

Ross had a son, Steven, from his first marriage to Lynda Brown. Steven occasionally appeared on The Joy of Painting and is a Bob Ross–certified instructor.^[1] Ross and Lynda's marriage ended in divorce in 1981. Ross married again, this time to Jane. Jane died of cancer in 1993,^[1] and Ross himself suffered from lymphoma in his later years. In early 1994, Ross cancelled The Joy of Painting to continue battling the disease, with his final show airing on May 17, 1994. On July 4, 1995, Ross died at home and was survived by his ex-wife Lynda, his son Steve, a half-brother, and a full brother.^[5][6] He is buried at Woodlawn Memorial Park in Gotha, Florida.^[7]

Ross had a brother Jim, whom he mentioned in passing on his show.^[8]

Television show[link]

Ross was the host of the public television series The Joy of Painting. The show ran from January 11, 1983 to May 17, 1994 and still^[update] appears in reruns in many broadcast areas and countries, including the PBS oriented Create. During each half-hour segment, Ross would instruct viewers in the art of oil painting using a quick-study technique that kept colors to a minimum and broke paintings down into simple steps that virtually anyone could follow. Art critic Mira Schor compared him to another PBS television host, noting that the softness of Ross's voice and the slow pace of his speech was similar to Fred Rogers.^[9]

Ross later founded his own successful line of art supplies and how-to books, and also offered painting classes taught by instructors trained in the "Bob Ross method," building a $15 million business.^[2] In a 1990 interview, Ross mentioned that all his programs were donated free of charge to PBS stations and that his earnings came instead from sales of his 20 books and 100 videotapes (the total to that date), as well as profits from some 150 Bob Ross-ATE teachers and a line of art materials sold through a national supplier.^[4] Ross also mentioned on the show "Towering Glacier" (#2341) that he donated all the paintings made on the show to PBS stations around the country to "help them out."^[10]

Ross also filmed wildlife footage, squirrels in particular, usually from his own garden. Small animals often appeared on his show, even during some of his trickier works, as he would often take in injured or abandoned squirrels and other assorted wildlife and look after them.^[4]

Painting[link]

Ross utilized the wet-on-wet oil painting technique, in which the painter continues adding paint on top of still wet paint rather than waiting a lengthy amount of time to allow each layer of paint to dry. Combining this method with the use of two inch and other types of brushes as well as painting knives allowed Ross to paint trees, water, clouds and mountains in a matter of seconds. Each painting would start with simple strokes that appeared to be nothing more than colored smudges. As he added more and more strokes, the blotches transformed into intricate landscapes.^[11][12] Ross dedicated the first episode of the second season of "The Joy of Painting with Bob Ross" to William Alexander, explaining that "years ago, Bill taught me this fantastic [wet-on-wet] technique, and I feel as though he gave me a precious gift, and I'd like to share that gift with you [the viewer]".^[13]

Ross noted that the landscapes he painted — typically mountains, lakes, snow, and log cabin scenes — were strongly influenced by his years living in Alaska, where he was stationed for the majority of his Air Force career. He repeatedly stated on the show his belief that everyone had inherent artistic talent and could become an accomplished artist given time, practice, and encouragement, and to this end was often fond of saying, "We don't have mistakes here, we just have happy accidents."^[14] Ross was well known for other catchphrases he used while painting as he crafted "happy little trees".^[15] In most episodes of The Joy of Painting, he noted that one of his favorite parts of painting was cleaning the brush, specifically his method of drying off a brush, which he had dipped in odorless thinner, by striking it against the thinner can and easel. He would smile and often laugh aloud as he "beat the devil out of it." He also used a palette which had been lightly sanded down which was necessary to avoid catching the reflections of strong studio lighting. At the end of each episode, Ross was known for saying, "so from all of us here, I'd like to wish you happy painting, and God bless my friend."

When asked about his laid-back approach to painting and eternally calm and contented demeanor, he once commented: "I got a letter from somebody here a while back, and they said, 'Bob, everything in your world seems to be happy.' That's for sure. That's why I paint. It's because I can create the kind of world that I want, and I can make this world as happy as I want it. Shoot, if you want bad stuff, watch the news."^[16]

Rivalry with William Alexander[link]

Bob Ross was a student of William Alexander, who hosted the public television series The Magic World of Oil Painting from the early 1970s until 1982. On his show, Alexander highlighted his mastery of the alla prima or wet-on-wet style of oil painting in order to promote his paint supply business, Alexander Art and his painting classes. Ross later became a Bill Alexander instructor. His series, The Joy of Painting, was picked up by many of the PBS stations that carried The Magic World of Oil Painting.^[17]

At the beginning of The Joy of Painting's second season in 1984, Ross dedicated the show to Alexander and Alexander filmed a promo for his former student: "I hand off my mighty brush to a mighty man, and that is Bob Ross."^[13][17] In 1987 someone from Alexander Art told Ross that they could not keep up with the demand generated by the The Joy of Painting and suggested that Ross start his own line of art supplies.^[17] As Bob Ross Incorporated grew into a $15 million a year business Alexander told the New York Times that he felt "betrayed" by his one-time student: "He betrayed me. I invented 'wet on wet.' I trained him and he is copying me -- what bothers me is not just that he betrayed me, but that he thinks he can do it better." ^[18]

In popular culture[link]

This "In popular culture" section may contain minor or trivial references. Please reorganize this content to explain the subject's impact on popular culture rather than simply listing appearances, and remove trivial references. (May 2012)

In "Derbez en Cuando" and "De Nuez en Cuando", two mexican comedy shows by Eugenio Dervez, who parodied this painter as "Bob Atroz"

Bob Ross was parodied in the Comedy Central program Tosh.0 in an episode where Tosh dressed up as Ross while conducting an interview with an artist from the web.

In 2006 a character loosely based off of Ross was featured in the popular comic based cartoon The Boondocks. In the episode an art teacher, Ross, takes Riley under his wing to help him improve his Graffitti.

Family Guy included a parody of Ross in the beginning of an episode.

An easter egg on homestarrunner.com features Marzipan dressed up as and painting like Ross.

He was also parodied by Benny Hill in a short gag, where his character is surrounded by wildlife and some animals end up attacking him. On a similar gag, parodied Ross is painting, then when he turns back to the camera a lady comes into scene and distracted Ross paints her buttocks in error, then she slaps him in the face.

During the Powerpuff Girls episode "Roughing It Up", Professor Utonium pays homage to Ross while he and the girls are painting in the woods, even using Ross's "happy little trees" catchphrase.

In season 2, episode 3 of Dilbert, "S02E03 - Art", a character sharing many traits of Ross named "Rusty Shanks" is shown demonstrating bizarre takes on abstract art, including painting using ones own head as the brush. The character is quickly hushed off-stage by men in black suits apparently sent as enforcers to collect outstanding debts from Rusty.

See also[link]

• Wet-on-wet

References[link]

External links[link]

Wikiquote has a collection of quotations related to: Bob Ross

• Bob Ross Incorporated
• Bob Ross at the Internet Movie Database