Glossary of Video Terms and Acronyms - Isotest

Video Terms and Acronyms
Glossary
2K – A film image scanned into a computer file at a resolution of 2048
horizontal pixels per line.
2T Pulse – See the discussion on Sine-Squared Pulses.
3-Perf – A concept for saving money on film stock by shooting each
35 mm frame in an area covered by three perforations rather than four.
The savings is more than enough to compensate for switching from 24
frames per second to 30. Three-perf naturally accommodates a 1.78:1
(16:9) aspect ratio and can be easily masked to the 1.85:1 common in
U.S. movie theaters. It changes the shoot-and-protect concept of using
theatrical film on television, however, from one in which the protected area
is extended vertically to one in which the shooting area is reduced
horizontally.
3.579545 MHz – The frequency of the NTSC color subcarrier.
3:2 Pull Down – a) The technique used to convert 24 frames per second
film to 30 frames per second video. Every other film frame is held for three
video fields resulting in a sequence of 3 fields, 2 fields, 3 fields, 2 fields,
etc. b) A frame cadence found in video that has been telecined or converted
from film to video. This cadence is produced because the frame rates
for film and video are different. During the process of compression, some
compression hardware recognizes this cadence and can further compress
video because of it. Material which is video to start with gains no extra
compression advantage. Material edited after being telecined may not gain
a compression advantage.
30 Hz HDTV Bitstream – A bitstream which contains only Main Profile,
High Level (or simpler) video at 24000/1001, 24, 30000/1001, 30,
60/1001 or 60 Hz frame rates.
30 Hz HDTV IRD – An IRD (Integrated Receiver Decoder) that is capable of
decoding and displaying pictures based on nominal video frame rates of
24000/1001, 24, 30000/1001, 30, 60/1001 or 60 Hz from MPEG-2 Main
Profile, High Level bitstreams, in addition to providing the functionality of a
30 Hz SDTV IRD.
30 Hz SDTV Bitstream – A bitstream which contains only Main Profile,
Main Level video at 24000/1001, 24, 30000/1001 or 30 Hz frame rate.
30 Hz SDTV IRD – An IRD (Integrated Receiver Decoder) which is capable
of decoding and displaying pictures based on a nominal video frame rate of
24000/1001 (approximately 23,98), 24, 3000/1001 (approximately 29,97)
or 30 Hz from MPEG-2 Main Profile at Main Level bitstreams.
30 Frames Per Second – Frame rate of NTSC prior to color. Frame rate of
the ATSC/SMPTE HDEP standard. A potential new film standard.
3D (Three Dimensional) – Either as in stereoscopic television (NHK has
suggested alternating 3DTV transmissions with HDTV), or more often, when
referring to ATV, relating to the three dimensions of the spatio-temporal
spectrum: horizontal, vertical, and time.
3D Axis (Menu) – The 3D function that moves the image away from the
center of rotation. The image can be moved along, or off any of the three
axes.
3D Space – Three dimensional space is easily imagined by looking at a
corner of a rectangular room. The corner is called the origin. Each edge
leaving from the origin (there are three of them) is called an axis. Each axis
extends infinitely in two directions (up/down, left/right, and front/back).
2 www.tektronix.com/video_audio
Imagine laying long measuring sticks on each axis. These are used to
locate specific points in space. On the Cubicomp, or any other graphics
systems, the yardsticks are not infinitely long, and 3D space on these
devices is not infinite; it is more like an aquarium.
3XNTSC – A Zenith proposal for an HDEP scheme that would use three
times as many scanning lines as NTSC (1575), but would otherwise retain
NTS characteristics. It is said to allow easy standards conversion to 525or
625-scanning line systems and to accept material shot in 1125 scanning
lines in a 16:9 aspect ratio without difficulty. 3XNTSC would have
1449 active scanning lines, 2:1 interlace, a 4:3 aspect ratio, and a bandwidth
of 37.8 MHz.
4:1:1 – 4:1:1 indicates that Y' has been sampled at 13.5 MHz, while Cb
and Cr were each sampled at 3.375 MHz. Thus, for every four samples of
Y', there is one sample each of Cb and Cr.
4:2:0 – A sampling system used to digitize the luminance and color difference
components (Y, R-Y, B-Y) of a video signal. The four represents the
13.5 MHz sampling frequency of Y, while the R-Y and B-Y are sampled at
6.75 MHz – effectively between every other line only.
4:2:2 – a) A commonly used term for a component digital video format.
The details of the format are specified in the CCIR-601 standard document.
The numerals 4:2:2 denote the ratio of the sampling frequencies of
the single luminance channel to the two color difference channels. For
every four luminance samples, there are two samples of each color difference
channel. b) ITU-R BT.601 digital component waveform sampling standard
where the luminance signal is sampled at the rate of 13.5 MHz, and
each of the color difference signals, (Cr and Cb) are sampled at the rate of
6.25 MHz each. This results in four samples of the luminance signal for
each two samples of the color difference signals. See ITU-R BT.601-2.
10 Bit
Y Sample
10 Bit
C r Sample
10 Bit
Y Sample
10 Bit
C b Sample
10 Bit
Y Sample
10 Bit
C r Sample
10 Bit
Y Sample
10 Bit
C b Sample
4:2:2p (Professional Profile) – 4:2:2p refers to a higher quality, higher
bitrate encoding designed for professional video usage. It allows multiple
encodings/decodings before transmission or distribution.
4:2:2:4 – Same as 4:2:2 with the addition of a key channel sampled at the
same frequency as the luminance.
4:4:4 – A sampling ratio that has equal amounts of the luminance and
both chrominance channels.
4:4:4:4 – Same as 4:2:2 with the addition of a key channel, and all channels
are sampled at the same frequency as the luminance.
45 Mbps – Nominal data rate of the third level of the hierarchy of ISDN in
North America. See also DS3.
4fsc – Composite digital video as used in D2 and D3 VTRs. Stands for four
times the frequency of subcarrier, which is the sampling rate used. In
NTSC, 4FSC is 14.3 MHz and in PAL it is 17.7 MHz.
4K – A film image scanned into a computer file at a resolution of 4096
horizontal pixels per line. 4K is considered to be a full-resolution scan of
35 mm film.