of digital ‘video’ formats now includes motion picture formats up to 4K and mobile TV operating in many formats down to 320x240, or 176x144 on phones. See also: Resolution co-existence
Resolving power
The resolving power of an imaging medium is a measure of its maximum spatial resolution. For digital media the pixel count dictates the maximum possible resolving power. For film it is assessed by exposing it to special test images comprising sine wave bars of successively higher frequencies. The results on the processed film are then judged by a panel of viewers – making them somewhat subjective. See also: MTF
Restoration
Hiding or removing the defects acquired by old (archive) material and content. Digital technology has enabled many new and easy-to-use procedures to provide fast and affordable restoration. These range from fully automated systems – that depend on recognizing generic faults and treating them – to hands-on operations that offer access to appropriate toolsets – often presented as ‘brushes’. These have been applied to both television and to film, and succeeded in making available many old archives for the ever-hungry TV channels.
Return control (path) Return control is needed for interactive television. It needs only to offer quite a low data rate but have little latency, as action should be followed as soon as possible by reaction. See also: WiMax
RGB
The abbreviation for the Red, Green and Blue signals, the primary colors of television. Cameras and telecines have red, green and blue receptors, the TV screen has red, green and blue phosphors or LEDs. RGB is digitized with 4:4:4 sampling which generates 50% more data than 4:2:2.
Rotoscoping
The practice of using frames of live footage as reference for painting animated sequences. Today, the meaning has extended to cover a whole range of manual retouching techniques. While the painting will always be down to the skill of the artist, modern graphics equipment integrated with a video disk or RAM store makes rotoscoping, or any graphical treatment of video frames, quick and easy. This has led to many new designs and looks appearing on television as well as the more mundane practices such as image repair.
RS 232
A standard for serial data communications defined by EIA standard RS- 232 that is designed for short distances only – up to 10 meters. It uses single-ended signaling with a conductor per channel plus a common ground, which is relatively cheap, easy to arrange but susceptible to interference – hence the distance limitation.
RS 422
Not to be confused with 4:2:2 sampling or 422P MPEG, this is a standard for serial data communications defined by EIA standard RS-422. It uses current-loop, balanced signaling with a twisted pair of conductors per channel, two pairs for bi-directional operation. It is more costly than RS232 but has a high level of immunity to interference and can operate over reasonably long distances – up to 300m/1000 ft. RS 422 is widely
used for control links around production and post areas for a range of equipment – VTRs, mixers, etc.
RSN
Real Soon Now. A phrase coined by Jerry Pournelle to satirize the tendency in the computer industry to discuss (and even offer for sale) things that are not actually available yet. See also: Vaporware
Run-length coding
A system for compressing data. The principle is to store a pixel value along with a message detailing the number of adjacent pixels with that same value. This gives a very efficient way of storing large areas of flat color and text but is not so efficient with pictures from a camera, where the random nature of the information, including noise, may actually mean that more data is produced than was needed for the original picture.
Safe area
The area of picture into which it is considered safe to place material, graphics, text or action, so that it will be viewable when received at home. Initially this was necessary with 4:3 aspect ratio screens as they were always overscanned to avoid showing the black that surrounds the active picture. Typically 5% in from the edges was considered safe. More recently the whole Safe Area issue has become far more complicated as there are both 4:3 and 16:9 displays, as well as 4:3, 16:9 and sometimes 14:9 (a compromised version of 16:9 that is more acceptable to those viewing on, generally analog, 4:3 screens) aspect ratios for program output. The transition to HD, always 16:9, ensures safe areas will need careful attention for many years yet. See also: Aspect ratio (of pictures)
SAIT-2
Super Advanced Intelligent Tape format that uses a 12.7mm (half-inch) wide tape and a helical scan format. It is designed for the general data storage market and is also used for the archive and transfer of file-based media data. SAIT-2 tape has a native capacity of 1 TB and a transfer rate of 60 MB/s, offering lossless compressed storage of 2.6 TB and transfer of 144 MB/s. There is a roadmap for SAIT-3 and SAIT-4 that speculatively predicts doubling of performance for each generation, projected for completion by 2010.
Sampling standard
A standard for sampling analog waveforms to convert them into digital data. The official sampling standard for 625/50 and 525/60 television is ITU-R BT.601. ITU-R BT.709 and SMPTE 274M specify sampling for HD formats. They are generally written as the number of pixels per line x number of lines per frame/vertical refresh rate (in Hz) progressive or interlaced (P or I). For example: 1920 x 1080/50I. Sometimes the pixel count of the lines is omitted (but understood), making the example 1080/50I.
SAN
Storage Area Networks are a well-established method of providing shared video storage and can offer platform-independent storage that may be accessed from, say, both Windows and Linux workstations. They allow applications direct access to shared storage by cutting out the usual client- server ‘middle men’ to provide improved workflow and better work sharing on a common store. See also: FAN, Fibre Channel, NAS Website:
www.snia.org
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GLOSSARY OF TERMS
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