Graphics
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Video is the technology of electronically capturing , recording , processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion. [ edit ] History Video technology was first developed for cathode ray tube (CRT) television systems, but several new technologies for video display devices have since been invented. Charles Ginsburg led an Ampex research team developing the first practical video tape recorder (VTR). In 1951 the first video tape recorder captured live images from television cameras by converting the camera's electrical impulses and saving the information onto magnetic video tape . Video recorders sold for $50,000 in 1956, and videotape cost $300 per one-hour reel. [ 1 ] However, prices steadily dropped over the years; in 1971, Sony began selling videocassette recorder (VCR) tapes to the public.
Video
Motion compensation is an algorithmic technique employed in the encoding of video data for video compression , for example in the generation of MPEG-2 files. Motion compensation describes a picture in terms of the transformation of a reference picture to the current picture. The reference picture may be previous in time or even from the future.
Motion compensation
Motion interpolation
Motion interpolation is a form of video processing in which intermediate animation frames are generated between existing ones, in an attempt to make animation more fluid. [ edit ] Applications Motion interpolation is used in various display devices such as HDTVs and video players, aimed at alleviating the video artifacts introduced by framerate conversions in fixed-framerate displays such as LCD TVs. Films are recorded at a frame rate of 24 frames per second (frame/s) and television is typically filmed at 25, 50, 30 or 60 frames per second (the first two being PAL, the other two from NTSC).
RGB 비트맵 그림의 맨 위 왼쪽 모퉁이에 웃는 얼굴 이 있다고 치자. 확대를 하면 커다란 웃는 얼굴은 오른쪽과 같이 보이게 된다. 각 사각형은 화소를 나타낸다.
Raster graphics
For multiplexing of several input data over shared media. In telecommunication , it is implemented through dynamic bandwidth allocation mechanisms, where it may particularly be used to resolve quality of service and latency issues. In streaming media applications, it enables quasi-simultaneous reception of input streams, such as video and audio . For improved access performance in computer memory and computer data storage .
Interleaving
The cathode ray tube ( CRT ) is a vacuum tube containing an electron gun (a source of electrons) and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms ( oscilloscope ), pictures ( television , computer monitor ), radar targets and others. CRTs have also been used as memory devices , in which case the visible light emitted from the fluoresecent material (if any) is not intended to have significant meaning to a visual observer (though the visible pattern on the tube face may cryptically represent the stored data). The CRT uses an evacuated glass envelope which is large, deep (i.e. long from front screen face to rear end), fairly heavy, and relatively fragile.
CRT
Overscan is extra image area around the four edges of a video image that may not be seen reliably by the viewer. It exists because television sets in the 1930s through 1970s were highly variable in how the video image was framed within the cathode ray tube (CRT). [ edit ] Origins of overscan Early televisions varied in their displayable area because of manufacturing tolerance problems. There were also effects from the early design limitations of linear power supplies, whose DC voltage was not regulated as well as in later switching-type power supplies.
Overscan
YUV pixel formats
YUV formats fall into two distinct groups, the packed formats where Y, U (Cb) and V (Cr) samples are packed together into macropixels which are stored in a single array, and the planar formats where each component is stored as a separate array, the final image being a fusing of the three separate planes. In the diagrams below, the numerical suffix attached to each Y, U or V sample indicates the sampling position across the image line, so, for example, V0 indicates the leftmost V sample and Yn indicates the Y sample at the (n+1)th pixel from the left. Subsampling intervals in the horizontal and vertical directions may merit some explanation.Chrominance
Chrominance ( chroma or C for short) is the signal used in video systems to convey the color information of the picture, separately from the accompanying luma signal (or Y for short). Chrominance is usually represented as two color-difference components: U = B' − Y' (blue − luma) and V = R' − Y' (red − luma). Each of these difference components may have scale factors and offsets applied to it, as specified by the applicable video standard. In composite video signals, the U and V signals modulate a color subcarrier signal, and the result is referred to as the chrominance signal; the phase and amplitude of this modulated chrominance signal correspond approximately to the hue and saturation of the color. In digital-video and still-image color spaces such as Y'CbCr , the luma and chrominance components are digital sample values. Separating RGB color signals into luma and chrominance allows the bandwidth of each to be determined separately.
3 AD (After Discovery) We first wrote about the Chroma Upsampling Error (CUE) back in April, 2001. At that time, we only told you half the story (because we had not worked out the second half yet). Now we're back again to give you the latest information on what is commonly referred to in the A/V community as the "Chroma Bug." If you are just now hearing about the Chroma Bug and you have come here looking for answers, you might be interested in how all of this started. We were first introduced to this problem by Richard Ansell of Snell & Wilcox just a little over three years ago.
Chroma Up-sampling Error
MPEG Format is used on several media. This picture relates some of the most known media to the MPEG Format version and container format ( TS and PS ) used. The Moving Picture Experts Group ( MPEG ) is a working group of experts that was formed by ISO and IEC to set standards for audio and video compression and transmission. [ 1 ] It was established in 1988 by the initiative of Hiroshi Yasuda ( Nippon Telegraph and Telephone ) and Leonardo Chiariglione [ 2 ] , who has been from the beginning the Chairman of the group. The first MPEG meeting was in May 1988 in Ottawa, Canada. [ 3 ] [ 4 ] [ 5 ] As of late 2005, MPEG has grown to include approximately 350 members per meeting from various industries, universities, and research institutions. MPEG's official designation is ISO/IEC JTC1 /SC29 WG11 - Coding of moving pictures and audio (ISO/IEC Joint Technical Committee 1, Subcommittee 29, Working Group 11). [ 6 ] [ 7 ] [ 8 ] [ 9 ]
MPEG
MPEG-2 system
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 data compression methods which permit storage and transmission of movies using currently available storage media and transmission bandwidth. [ edit ] Main characteristics MPEG-2 is widely used as the format of digital television signals that are broadcast by terrestrial (over-the-air), cable , and direct broadcast satellite TV systems. It also specifies the format of movies and other programs that are distributed on DVD and similar discs. As such, TV stations , TV receivers , DVD players, and other equipment are often designed to this standard. MPEG-2 was the second of several standards developed by the Moving Pictures Expert Group ( MPEG ) and is an international standard ( ISO / IEC 13818).PSI is carried in the form of a table structure. The table structure can span multiple transport stream packets. Adaptation field also occurs in TS packets carrying PSI data. The PSI data will never be scrambled so that the decoder at the receiving end can easily identify the properties of the stream. The PAT, CAT and TDT tables are associated with predefined PID as explained in the respective sections.
PSI
Digital storage media command and control ( DSM-CC ) is a toolkit for developing control channels associated with MPEG-1 and MPEG-2 streams. It is defined in part 6 of the MPEG-2 standard (Extensions for DSM-CC) and uses a client/server model connected via an underlying network (carried via the MPEG-2 multiplex or independently if needed). DSM-CC may be used for controlling the video reception, providing features normally found on Video Cassette Recorders ( VCR ) (fast-forward, rewind, pause, etc). It may also be used for a wide variety of other purposes including packet data transport. It is defined by a series of weighty standards, principally MPEG-2 ISO / IEC 13818-6 (part 6 of the MPEG-2 standard).