PALsite: Glossary A-D

PALsite
Glossary A-D

http://www.PALsite.com

The home of the PAL system

Home

A-D

3:2 Pulldown: The technique used to convert 24 frames per second film to 30 frames per second video. Every other film frame is held for 3 video fields resulting in a sequence of 3 fields, 2 fields, 3 fields,2 fields, etc. (See Fields, Frames)
4 fsc: Composite Digital video as used in D2 and D3 VTRs. Stands for 4 times the Frequency of Sub-carrier, which is the sampling rate used.
4:2:2: The sampling ratio used in the D1 (CCIR 601) digital video signal. For every 4 samples of luminance there are 2 samples each of the colour difference signals, R-Y (Red minus Luminance) and B-Y (Blue minus luminance).
4:1:1: The sampling ratio used in the DV or DVC (Digital Video, Digital Video Tape) digital video signal. For every 4 samples of luminance there is 1 sample each of the colour difference signals, R-Y (Red minus Luminance) and B-Y (Blue minus luminance).
4:2:0: The sampling ratio used in some variations of DV digital video signal. For every 4 samples of luminance there is a sample of one of the colour difference signals, followed by a sample of the other colour difference signal on the next luminance sample.
4:4:4: A sampling ratio that has equal amounts of the luminance and both chrominance channels. Can also be used for RGB sampling, the colour space used in most computer programs.
16x9: (16 by 9) A wide screen television format in which the aspect ratio of the screen is 16 units wide by 9 high as opposed to the 4x3 of normal TV.
A/B roll edit: An edit in which two or more players are used to create special effects such as dissolve and wipe, and one recorder is used to record the results of the edit. Using an editing controller allows efficient control of the VTRs and very precise editing.
A-Frame Edit: A video edit which starts on the first frame of the 5 video frame (4 film frame) sequence created when 24 frame film is transferred to 30 frame video (see 3:2 pulldown). The A-frame is the only frame in the sequence where a film frame is completely reproduced on one and only one complete video frame. Here is the full sequence. (The letters correspond to film frames.) A-frame = video fields 1&2, B-frame = video fields 1&2&1, C-frame = video fields 2&1, D-frame = video fields 2&1&2.
A-Mode Edit: An editing method where the footage is assembled in the final scene order. Scene 1, scene 2, ...
Absolute Beta: This is a USA based firm which deal in all things Betamax.
Active Picture Area: The part of a TV picture that contains actual image information as opposed to sync or other data. Vertically the active picture area is 486 lines for NTSC and 576 lines for PAL. The inactive area is called blanking.
AES/EBU: The digital audio standard set by the Audio Engineering Society and European Broadcast Union and used by most forms of digital audio from CDs to D1.
AFM: Audio Frequency modulation. This is the professional term for Hi-Fi Audio where the audio tracks are frequency modulated on the tape using high frequency carriers. The performance is far superior to linear tracks.
Aliasing: Defects in the picture caused by too low a sampling rate or poor filtering. Usually seen as "jaggies" or stair steps in diagonal lines.
Analogue: A signal that varies continuously over a range of amplitudes. A digital signal by contrast has only two values, representing 1 or 0.
Anti-aliasing: The process of removing aliasing artefacts.
APS - Automatic Picture Search: This is the Betamax indexing system whereby tone was recorded on the tape at the start of each recording which allowed that point on the tape to be found again easily. Only a limited number of machines had this facility.
Artefact: A visual effect caused by an error or limitation in the system.
Aspect Ratio: The ratio of width to height in a picture. Cinema screens generally have an aspect ratio of 1.85 to 1, widescreen TV (16x9) is 1.77 to 1, and normal TV (4x3) is 1.33 to 1.
Audio Dub (Insert): The ability to dub over the linear audio track. The hifi track is left unaltered.
Audio Head: This is the audio record/replay head in the VCR. It's function is similar to that in an audio cassette recorder. It is situated to the right of the circular video head block. See also the ACE page.
Auto Assembly: An edit in which an off-line edit decision list is loaded into an on-line edit computer and all the edits are assembled automatically with little or no human intervention.
Auto Changer: This was a device which allowed the VCR to automatically change the video tape! This allowed for some very long unattended recording times, with the only disadvantage being the twenty seconds lost whilst switching tapes.
B-Mode Edit: An editing method where the footage is assembled in the order it appears on the source reels. Missing scenes are left as black holes to be filled in by a later reel. Requires fewer reel changes and generally results in a faster edit session.
B-Y signal: A chrominance signal determined by subtracting the Y (luminance) signal from the B (blue) signal. This is one of the component signals.
Back tension: The tension put on the tape to make sure it is taught when it passes the heads. See also Forward-Back Tension Measurement tape.
Balanced: This term refer to a way of connecting audio between VTRs using 3-pin XLR connectors. Using Balanced Audio reduces noise pick up introduced through interference.
Bandwidth: Bandwidth The amount of information that can be passed through a given circuit in a given time. In the case of video, the larger the bandwidth the greater the picture detail can be. It is a measure of the finest detail that can be recorded and played back (resolution).
Betacam: An analogue videotape format using 12.5mm tape developed by Sony and derived from the earlier Betamax. Also includes Betacam SP (Superior Performance), and digital versions Digital Betacam and Betacam SX.
Beta Chronicles: This was inatially a web site run by Steve Smyth [email protected] but has recently become an e-mail mailing list. The URL was http://home1.gte.net/spsmyth/index.html and the address to send to the mailing list is [email protected].
Beta Club Digest: This was an e-mail mailing list run by Tony Cianfaglione [email protected]. Sadly it does not exist any more. Back issues are available on the web.
Beta Noise Reduction (BNR): This is a noise reduction system used on some Betamax VCR's to reduce tape hiss on the linear audio track.
Beta modes I, II and III: These are the three modes of operation of an NTSC Betamax. Beta II is the original standard. Beta III is a mode whereby the tape speed is reduced to allow more material to be fitted on to a fixed length tape. Beta I uses a high tape speed for improved picture quality. PAL Betamax machines run at the equivalent of Beta II speeds.
Betacam: This is Sony professional broadcast quality video format. Do not confuse it with Betamax! Certain Betacam tapes ( 5, 10, 20 and 30 minutes oxide only ) can be used in Betamax VCR's but Betacam recordings can not be played on a Betamax machine or vice-versa.
Betacord: Sanyo's name for the Betamax video system.
Betamax: Superior video cassette format developed by Sony.
Betamax Chat Page: This is a web based discussion forum for all things Betamax. The URL is http://www.chat-page.com/betamax/.
Betaphile: A supporter of the Betamax format.
Betaphile Club: This was a US based Betamax supporters club. Sadly it does not exist any more.Details can be found on the web.
Blanking: The part of the video signal that contains no picture information. Used for synchronising, timecode, closed captions, etc.
BNC Connector: This is the connector used on many Betamax video recorders for video line in and output.
Bridging connection: A connection that allows a signal input to an input terminal to pass through the unit and exit from an output terminal as input to external equipment. Also called loop-through connection.
Broadcast Quality: A nebulous term used to describe the output of a manufacturer's product . Usually at least means that the technical specifications meet the FCC rules for broadcasting.
BRS: Series of Sony U-matic tapes intended for Hi-Band use.
BVU: BVU Broadcast Video U-matic (High band/SP)
Capstan: This is the metal rod which together with the Pinch Roller pulls the tape through the VCR at a specified speed. Both items should be cleaned regularly so as to ensure smooth tape transport. See also pinch roller.
Capstan Motor: This is the electronic motor which turns the capstan.
Carriage: This is the mechanism in which the video cassette sits. See also a picture of the SLC9 carriage.
Cassette: This is the tape and housing onto which video recordings are made. See also the Betamax tape gallery.
CBR: Constant Bit Rate. A variety of MPEG video compression where the amount of compression does not change.
CCIR 601: The standard for digitising component video. Also sometimes called D1 after the VTR format that first used this signal. (see also 4:2:2)
Chrominance: The signal which carries the colour information in video.
Chrominance signal: Colour signal containing colour information such as hue and saturation. Also called C signal.
Colour Frame: A sequence of four fields (2 frames) of NTSC video. Since the phase of the colour sub-carrier reverses every frame in NTSC (which makes the colour information essentially invisible on a black-and-white receiver) two complete frames are required to carry a complete sequence of colour information. So the cycle consists of two frames (four fields) in NTSC format and four frames (eight fields) in PAL format.
Colour framing: Maintenance of continuity in the colour sub-carrier phase between one frame and the next, for the purpose of avoiding noise on the picture.
Colour Sub-carrier: The portion of the video signal that carries the colour information. Colour signals are quadrature modulated onto a sub-carrier of 3.579545 MHz in NTSC.
Component Video: A video signal in which the Luminance and Chrominance signals are kept separate. This requires a higher bandwidth, but yields a higher quality picture.
Composite Video: The luminance and chrominance signals are combined in an encoder to create the common NTSC, PAL or SECAM video signals. Allows economical broadcasting of video.
Control Track: The is a signal recorded on the video tape which is used to sync up the VCR during playback. It allows a video tape to play back at a precise speed in any VTR. Analogous to the sprocket holes on film. See also the ACE assembly.
CRT Cathode Ray Tube: The technical name for a picture tube, a camera tube or the scanning tube in a flying spot telecine.
CTDM: An abreviation for Compressed Time Division Multiplex. This compression method is used in Betacam SP machines to combine the two colour differnce signals together before recording it onto the tape to form a single C signal.
CTL: Abbreviation of control signal. A pulse signal recorded on a longitudinal track of the tape in units of fields. Counting this signal allows the number of frames to be used to display the tape running time. It is also used as a control signal to adjust the relationship between the scanning position of the video beads and tape movement during playback to match that during recording.
Counter: This is the indicator which tells you how far through a tape you are. A real-time counter is one which gives a reading in hours, minutes and seconds.
Cue/Review: The ability of the VCR to fast search/review through the tape without muting the picture. Also known as picture search.
Crystal Lock: This is a means of controlling the clock with in the VCR. As the name suggests the clock is locked to a reference generated by a crystal, usually Quartz, in the same was as implemented in digital watches.
Cross Talk: Interference of one signal with another.
Drum: This is the cylinder around which the tape passes and contains the video head disc. See also the complete drum assembly and upper drum pages.
Colour Frame: This is a part of the PAL colour signal through which color information is synchronised together.