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Tektronix provides test and measurement instruments, solutions and services for the computer, semiconductor, military/aerospace, consumer electronics and education industries worldwide.
In composite NTSC, PAL or S-video systems, it is necessary to scale (B-Y) and (R-Y) so that the composite ntsc or pal signal (luma plus modulated chroma) is contained within the range -1/3 to +4/3. These limits reflect the capability of composite signal recording or transmission channel.
The scale factors are obtained by two simultaneous equations involving both B-Y and R-Y, because the limits of the composite excursion are reached at combinations of B-Y and R-Y that are intermediate to primary colours. The scale factors are as follows: U = 0.493 * (B - Y) V = 0.877 * (R - Y) U and V components are typically modulated into a chroma component: C = U*cos(t) + V*sin(t) where t represents the ~3.58 MHz NTSC colour sub-carrier.
PAL coding is similar, except that the V component switches Phase on Alternate Lines (+-1), and the sub-carrier is at a different frequency, about 4.43 MHz. It is conventional for an NTSC luma signal in a composite environment (ntsc or S-video) to have 7.5% setup: Y_setup = (3/40) + (37/40) * Y A pal signal has zero setup. The two signals Y (or Y_setup) and C can be conveyed separately across an S-video interface, or Y and C can be combined (encoded) into composite NTSC or PAL: NTSC = Y_setup + C PAL = Y + C U and V are only appropriate for composite transmission as 1-wire NTSC or PAL, or 2-wire S-video. The UV scaling (or the IQ set, described below) is incorrect when the signal is conveyed as three separate components. Certain component video equipment has connectors labelled YUV that in fact convey ypbpr signals.
Industry:Entertainment
When a roll of 16mm film, perforated along one edge, is held so that the outside end of the film leaves the roll at the top and toward the right, winding "A" should have the perforations on the edge of the film toward the observer, and winding "B" should have the perforations on the edge away from the observer. In both cases, the emulsion surface should face inward on the roll.
Industry:Entertainment
Video editing arrangement where scenes are edited from two source VCRs ("A" and "B") to a third (recording) VCR. Typically a switcher or mixer is used to provide transition effects between sources. Control over the machines and process can be done manually or automatically using an edit controller.
Industry:Entertainment
The human visual system has much less acuity for spatial variation of colour than for brightness. Rather than conveying RGB, it is advantageous to convey luma in one channel, and colour information that has had luma removed in the two other channels. In an analogue system, the two colour channels can have less bandwidth, typically one-third that of luma. In a digital system each of the two colour channels can have considerably less data rate (or data capacity) than luma. Green dominates the luma channel: about 59% of the luma signal comprises green information. Therefore it is sensible, and advantageous for signal-to-noise reasons, to base the two colour channels on blue and 1red. The simplest way to remove luma from each of these is to subtract it to form the difference between a primary colour and luma. Hence, the basic video colour-difference pair is (B-Y), (R-Y) (pronounced "B minus Y, R minus Y"). The (B-Y) signal reaches its extreme values at blue (R=0, G=0, B=1; Y=0.114; B-Y=+0.886) and at yellow (R=1, G=1, B=0; Y=0.886; B-Y=-0.886). Similarly, the extrema of (R-Y), +-0.701, occur at red and cyan. These are inconvenient values for both digital and analogue systems. The colour spaces YPbPr, YCbCr, PhotoYCC and YUV are simply scaled versions of (Y, B-Y, R-Y) that place the extrema of the colour difference channels at more convenient values.
Industry:Entertainment
A standard platform for mass consumer interactive multimedia applications. So it is more akin to CD-DA, in that it is a full specification for both the data/code and standalone playback hardware: a CD-I player has a CPU, RAM, ROM, OS, and audio/video/(MPEG) decoders built into it. Portable players add an LCD screen and speakers/phonejacks. It has limited motion video and still image compression capabilities. It was announced in 1986, and was in beta test by Spring 1989.
This is a consumer electronics format that uses the optical disc in combination with a computer to provide a home entertainment system that delivers music, graphics, text, animation, and video in the living room. Unlike a CD-ROM drive, a CD-I player is a standalone system that requires no external computer. It plugs directly into a TV and stereo system and comes with a remote control to allow the user to interact with software programmes sold on discs. It looks and feels much like a CD player except that you get images as well as music out of it and you can actively control what happens. In fact, it is a CD-DA player and all of your standard music CDs will play on a CD-I player; there is just no video in that case.
For a CD-I disk, there may be as few as 1 or as many as 99 data tracks. The sector size in the data tracks of a CD-I disc is approximately 2 kbytes. Sectors are randomly accessible, and, in the case of CD-I, sectors can be multiplexed in up to 16 channels for audio and 32 channels for all other data types. For audio these channels are equivalent to having 16 parallel audio data channels instantly accessible during the playing of a disk.
Industry:Entertainment
CD-XA is a CD-ROM extension being designed to support digital audio and still images.
Announced in August 1988 by Microsoft, Philips, and Sony, the CD-ROM XA (for Extended Architecture) format incorporates audio from the CD-I format. It is consistent with ISO 9660, (the volume and the structure of CD-ROM), is an application extension of the Yellow Book, and draws on the Green Book.
CD-XA defines another way of formatting sectors on a CD-ROM, including headers in the sectors that describe the type (audio, video, data) and some additional info (markers, resolution in case of a video or audio sector, file numbers, etc).
The data written on a CD-XA can still be in ISO9660 file system format and therefore be readable by MSCDEX and Unix CD-ROM file system translators. A CD-I player can also read CD-XA discs even if its own `Green Book' file system only resembles ISO9660 and isn't fully compatible. However, when a disc is inserted in a CD-I player, the player tries to load an executable application from the CD-XA, normally some 68000 application in the /CDI directory. Its name is stored in the disc's primary volume descriptor. CD-XA bridge discs, like Kodak's Photo CDs, do have such an application, ordinary CD-XA discs don't.
A CD-DA drive is a CD-ROM drive but with some of the compressed audio capabilities found in a CD-I player (called ADPCM). This allows interleaving of audio and other data so that an XA drive can play audio and display pictures (or other things) simultaneously. There is special hardware in an XA drive controller to handle the audio playback. This format came from a desire to inject some of the features of CD-I back into the professional market.
Industry:Entertainment
Recognising the need for providing ubiquitous video services using the Integrated Services Digital Network (ISDN), CCITT (International Telegraph and Telephone Consultative Committee) Study Group XV established a Specialist Group on Coding for Visual Telephony in 1984 with the objective of recommending a video coding standard for transmission at m x 384 kbit/s (m=1,2,..., 5). Later in the study period after new discoveries in video coding techniques, it became clear that a single standard, p x 64 kbit/s (p = 1,2,..., 30), can cover the entire isdn channel capacity. After more than five years of intensive deliberation, CCITT Recommendation H.261, Video Codec for Audiovisual Services at p x 64 kbit/s, was completed and approved in December 1990. A slightly modified version of this Recommendation was also adopted for use in North America. The intended applications of this international standard are for videophone and videoconferencing. Therefore, the recommended video coding algorithm has to be able to operate in real time with minimum delay. For p = 1 or 2, due to severely limited available bit rate, only desktop face-to-face visual communication (often referred to as videophone) is appropriate. For p>=6, due to the additional available bit rate, more complex pictures can be transmitted with better quality. This is, therefore, more suitable for videoconferencing.
Industry:Entertainment
A defect of photographic films and plates. Light forming an image on the film is scattered by passing through the emulsion or by reflection at the emulsion or base surfaces. This scattered light causes a local fog which is especially noticeable around images of light sources or sharply defined highlight areas.
Industry:Entertainment
High-Definition Television. A television system with approximately twice the horizontal and twice the vertical resolution of current 525-line and 625-line systems, component colour coding (e.g. RGB or (YCbCr)) a picture aspect ratio of 16:9 and a frame rate of at least 24 Hz. Currently there are a number of proposed HDTV standards, including HD-MAC, HiVision and others.
Industry:Entertainment
An improved version of the 8mm tape format capable of recording better picture resolution (definition). A higher-density tape is required which provides a wider luminance bandwidth, resulting in sharper picture quality (over 400 horizontal lines vs. 240 for standard 8mm) and improved signal-to-noise ratio. Camcorders using this format are very small, light and provide a picture quality similar to S-VHS.
Industry:Entertainment
