ATV
Advanced Television. The term used in North America to describe television with capabilities beyond those of analog NTSC. It is generally taken to include digital television (DTV) and high definition (HDTV).
Auditory masking
The psycho-acoustic phenomenon of human hearing where what can be heard is affected by the components of the sound. For example, a loud sound will mask a soft sound close to it in frequency. Audio compression systems such as Dolby Digital and MP3 audio use auditory masking as their basis and only code what can be heard by the human ear. See also: Dolby Digital, MP3
AVC See MPEG-4
AVCHD Advanced Video Codec High Definition, a joint development between Panasonic and Sony, applies MPEG-4’s AVC video coding and Dolby Digital (AC-3) or linear PCM audio coding, to meet the needs of the high definition consumer market with 1080i and 720p formats. The use of AVC provides at least twice the efficiency of MPEG-2 coding, used in HDV and MiniDV, to offer longer recording times or better pictures – or both. Possible recording media include standard DVD disks, flash memory and hard drives.
AVC-Intra
A codec that is H.264-compliant and uses only intra-frame compression. AVC-Intra technology, aimed at professional users, has been adopted by Panasonic for its P2 cameras (AVC-Intra P2) and offers considerably more efficient compression than the original DVCPRO HD codec – maybe as much as 2:1. See also: DVCPRO P2, MPEG-4
AVI (.avi) Audio Video Interleave – a Microsoft multimedia container format introduced in 1992 as part of its Video for Windows technology. AVI files can hold audio and video data in a standard container and provide synchronous video/audio replay. Most AVI files also use the OpenDML file format extensions, forming AVI 2.0 files. Some consider AVI outdated, as there are significant overheads using it with popular MPEG-4 codecs that seemingly unduly increase file sizes. Despite that, it remains popular among file-sharing communities – probably due to its high compatibility with existing video editing and playback software, such as Windows Media Player.
Background loading
Recording material into a system, such as a nonlinear editor, as a background task. Thus the foreground task continues uninterrupted and when one job is completed, the next is already loaded – potentially increasing the throughput of the editing system.
Background task A secondary operation that is completed while the main (foreground) operation continues uninterrupted. This requires an overhead in machines’ capabilities beyond that needed for their primary foreground operation. This has particular benefits in pressured situations where time is short, or simply not available for extra operations – such as during edit sessions, live programming and transmission.
Bandwidth The amount of information that can be passed in a given time. In television a large bandwidth is needed to show sharp picture detail in real time, and so is a factor in the quality of recorded and transmitted images. Digital image systems generally require large bandwidths hence the reason why many storage and transmission systems revert to compression techniques to accommodate the signal.
Bayer filter/mask array Color filter A Bayer array is a pattern of red, green and blue non co-sited filters placed onto an imaging chip (CCD, CMOS) so that it can capture the separate red, blue and green primary colors of the image to make up a color digital image. As our eyes have more resolution for green light than red or blue, there are twice as many green cells as there are red and blue. Some redundancy of the green pixels produces an image which is less noisy and has finer detail than would be achieved if there were and equal number of red, green and blue cells. The R, G and B pixels generated by the Bayer filter need to be ‘unmasked’ using a complex algorithm to produce white. Traditionally professional TV cameras have used three image sensors, one to pick up each primary color. This arrangement demands that the three are finely registered together and involves a considerably more bulky construction and cost than the still digital cameras and consumer camcorders that use a single chip sensor with a Bayer, or other similar filter. However some new high-end professional cameras now have just one sensor, for example the ARRI D20 and Red.
Best light (pass)
Shot by shot color correction to produce the best result for each shot. Betacam
An analog component VTR system for PAL and NTSC television introduced in 1982, using a half-inch tape cassette – very similar to the domestic Betamax. This was developed by Sony and was marketed by them and several other manufacturers. Betacam records the Y, R-Y and B-Y component signals onto tape; many machines were operated with coded (PAL or NTSC) video in and out. Initially developed for the industrial and professional markets the system was enhanced to offer models with full luminance bandwidth (Betacam SP 1986), PCM audio and SDI connections with a great appeal to the broadcast market.
Digital Betacam
Introduced in 1990 it was a development of the original analog Betacam VTR that records SD component video and audio digitally onto Betacam- style cassettes. It uses mild intra-field compression to reduce the ITU-R BT.601 sampled video data by about 2:1 to provide a good and much cheaper alternative to the uncompressed D1 format. Betacam SX (1996) was a digital tape recording format which uses a constrained version of MPEG-2 compression at the 4:2:2 profile, Main Level (422P@ML). The compression is 10:1 and uses a 2-frame GOP (one I and one B frame), making it more difficult to edit. It uses half-inch tape cassettes. See also: MPEG-2
B-frames See MPEG-2
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GLOSSARY OF TERMS
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