Cameras The basis for
digital video cameras is
metal–oxide–semiconductor (MOS)
image sensors. The first practical
semiconductor image sensor was the
charge-coupled device (CCD), invented in 1969 by Willard S. Boyle, who won a Nobel Prize for his work in physics. Following the commercialization of CCD sensors during the late 1970s to early 1980s, the
entertainment industry slowly began transitioning to
digital imaging and digital video from analog video over the next two decades. The CCD was followed by the
CMOS active-pixel sensor (
CMOS sensor), developed in the 1990s. Major movies shot on digital video overtook those shot on film in 2013. Since 2016, over 90% of major movies have been shot on digital video. , 92% of films are shot on digital. Only 24 major movies released in 2018 were shot on 35mm. Today, cameras from companies like
Sony,
Panasonic,
JVC and
Canon offer a variety of choices for shooting high-definition video. At the high end of the market, there has been an emergence of cameras aimed specifically at the digital cinema market. These cameras from
Sony,
Vision Research,
Arri,
Blackmagic Design,
Panavision,
Grass Valley and
Red offer resolution and
dynamic range that exceeds that of traditional video cameras, which are designed for the limited needs of
broadcast television.
Coding In the 1970s,
pulse-code modulation (PCM) induced the birth of digital
video coding, demanding high
bit rates of 45-140 Mbit/s for
standard-definition (SD) content. By the 1980s, the
discrete cosine transform (DCT) became the standard for digital
video compression. The first digital
video coding standard was
H.120, created by the (International Telegraph and Telephone Consultative Committee) or
CCITT (now ITU-T) in 1984. H.120 was not practical due to weak performance. H.120 was based on
differential pulse-code modulation (DPCM), a compression algorithm that was inefficient for video coding. During the late 1980s, a number of companies began experimenting with DCT, a much more efficient form of compression for video coding. The CCITT received 14 proposals for DCT-based video compression formats, in contrast to a single proposal based on
vector quantization (VQ) compression. The
H.261 standard was developed based on DCT compression, becoming first practical video coding standard. The current-generation video coding format is
HEVC (H.265), introduced in 2013. While AVC uses the integer DCT with 4x4 and 8x8 block sizes, HEVC uses integer DCT and
DST transforms with varied block sizes between 4x4 and 32x32. HEVC is heavily patented, with the majority of patents belonging to
Samsung Electronics,
GE,
NTT and
JVC Kenwood. It is currently being challenged by the aiming-to-be-freely-licensed
AV1 format. , AVC is by far the most commonly used format for the recording, compression and distribution of video content, used by 91% of video developers, followed by HEVC, which is used by 43% of developers.
Production Starting in the late 1970s to the early 1990s,
video production equipment that was analog in its internal workings was introduced. These included
time base correctors (TBC) and
digital video effects (DVE) units. 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 was then converted back to standard analog video for output. In the 1990s, the transition from analog took place. The beginning of the 21st century brought with it high-definition digital video. Later on in the 1970s, manufacturers of professional video broadcast equipment, such as
Bosch (through their
Fernseh division) and
Ampex developed prototype digital
videotape recorders (VTR) in their research and development labs. Bosch's machine used a modified
1-inch type B videotape transport and recorded an early form of
CCIR 601 digital video. Ampex's prototype digital video recorder used a modified
2-inch quadruplex videotape VTR (an Ampex AVR-3) fitted with custom digital video electronics and a special
octaplex 8-head headwheel (regular analog 2" quad machines only used 4 heads). Like standard 2" quad, the audio on the Ampex prototype digital machine, nicknamed
Annie by its developers, still recorded the audio in analog as linear tracks on the tape. None of these machines from these manufacturers was ever marketed commercially. Digital video was first introduced commercially in 1986 with the Sony
D1 format, which recorded an uncompressed standard definition
component video signal in digital form. ONe of many formats during this time came and went. Component video connections required 3 cables, but most
television facilities were wired for composite NTSC or PAL video using one cable. Due to this incompatibility, the cost of the recorder, D1 was used primarily by large
television networks and other component-video capable video studios. In 1988, Sony and Ampex co-developed and released the
D2 digital videocassette format, which recorded video digitally without compression in
ITU-601 format, much like D1. In comparison, D2 had the major difference of encoding the video in composite form to the NTSC standard, thereby only requiring single-cable composite video connections to and from a D2 VCR. This made it a perfect fit for the majority of television facilities at the time. D2 was a successful format in the
television broadcast industry throughout the late '80s and the '90s. D2 was also widely used in that era as the master tape format for mastering
laserdiscs. D1 & D2 would eventually be replaced by cheaper systems using video compression, most notably Sony's
Digital Betacam, that were introduced into the network's
television studios. Other examples of digital video formats utilizing compression were Ampex's
DCT (the first to employ such when introduced in 1992), the industry-standard
DV and MiniDV and its professional variations, Sony's
DVCAM and Panasonic's
DVCPRO, and
Betacam SX, a lower-cost variant of Digital Betacam using MPEG-2 compression. 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. It was developed starting in 1990 and first shipped in May 1991. PACo could stream unlimited-length video with synchronized sound from a single file (with the
.CAV file extension) on CD-ROM. Creation required a Mac, and playback was possible on Macs, PCs, and Sun
SPARCstations.
QuickTime,
Apple Computer's multimedia framework, was released in June 1991.
Audio Video Interleave from
Microsoft followed in 1992. 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 the introduction of the
DV tape format allowing recordings in the format to be transferred directly to digital video files using a
FireWire port on an editing computer. This simplified the process, allowing
non-linear editing systems (NLE) to be deployed cheaply and widely on
desktop computers with no external playback or recording equipment needed. The widespread adoption of digital video and accompanying compression formats has reduced the
bandwidth needed for a
high-definition video signal (with
HDV and
AVCHD, as well as several professional formats such as
XDCAM, all using less bandwidth than a standard definition analog signal). These savings have increased the number of channels available on
cable television and
direct broadcast satellite systems, created opportunities for
spectrum reallocation of
terrestrial television broadcast frequencies, and made
tapeless camcorders based on
flash memory possible, among other innovations and efficiencies.
Culture Culturally, digital video has overtaken film to become widely available and popular, beneficial to entertainment, education, and research. Digital video is increasingly common in schools, with students and teachers taking an interest in learning how to use it in relevant ways. Digital video also has healthcare applications, allowing doctors to track infant heart rates and oxygen levels. In addition, the switch from analog to digital video impacted media in various ways, such as in how businesses use cameras for surveillance.
Closed circuit television (CCTV) switched to using
digital video recorders (DVR), presenting the issue of how to store recordings for evidence collection. Today, digital video is able to be
compressed in order to save storage space.
Digital television Digital television (DTV) is the production and transmission of digital video from networks to consumers. This technique uses digital encoding instead of analog signals used prior to the 1950s. As compared to analog methods, DTV is faster and provides more capabilities and options for data to be transmitted and shared. Digital television's roots are tied to the availability of inexpensive, high-performance
computers. It was not until the 1990s that digital TV became a real possibility. Digital television was previously not practically feasible due to the impractically high bandwidth requirements of
uncompressed video, requiring around 200
Mbit/s for a
standard-definition television (SDTV) signal, and over 1
Gbit/s for
high-definition television (HDTV). ==Overview ==