Audio-Visual Glossary



“0.1” CHANNEL: Indicates a subwoofer may be used with a surround sound loudspeaker audio system. “5.1” is five channels of full audio information plus one subwoofer—the “point 1”.


1.33:1: Aspect ratio for analogue TV and most 16mm film projection.


1.85:1: One of two aspect ratios used for letterboxed t.v. video. (See ASPECT RATIO, see DVD SCREEN SIZES for more information.)


2 ch + BASS:       A feature on some home DVD equipment that allows one to listen to stereo sound plus a totally separate (and adjustable) channel for a subwoofer. Panasonic makes DVD players that provide this feature. 


2 CHANNEL SURROUND:  Some home consumer surround sound audio equipment may be set to “2 channel surround” (or similar setting), if the consumer has only a left and right loudspeaker - no surround speakers and no centre channel speaker. This setting puts the centre channel dialog information of a surround sound film mix, plus the ambience information of the mix, into the left and right speakers. It sounds better than just simply playing the mix with a “stereo” setting.


2 kHz DIP:   In mixing there is a small drop in the 2,000 cycle frequency range when one moves a sound out of one speaker, and pans it between two speakers. This is in comparison to the sound being only in one loudspeaker as opposed to located “in space” (as a “phantom image”) between a pair of stereo speakers. When the sound is a phantom image between the two loudspeakers, there is a characteristic slight drop in this frequency area.


2-POP:   See SYNC POP.


2:35.1 :  The aspect ratio of some Letterboxed films when played on TV or video projector. This is a very wide format, wider than the usual Hollywood film release. The Drug Rehab film, shot for the LRH Life Exhibition, is in this format.


2-WAY DIFFUSERS:   Special sound treatment devices that have many angles with which to reflect sound. The multi-angled surfaces of a 2 way diffuser reflect the sound back into the room in lots of different directions. This tends to make the room sound bigger than it actually is. Such treatments are sometimes used in smaller listening rooms to make them sound more spacious. For example, there are 2-Way diffusers in some org film rooms. They can be seen up high on the rear wall.


6.1: Multi-channel surround consisting of 6 main channels:  A front left, front centre, front right, surround right, surround left, and a single channel in the back for one or more speakers. The “.1” channel is a Low-Frequency-Effects (LFE) sub-woofer channel. This refers to DOLBY DIGITAL SURROUND EX and DTS ES surround both in theatres and in consumer home systems. Dolby Digital THX EX has 7.1 surround sound capability in theatres (two rear channels of surround). And Sony’s SDDS system, for professional theatres only, is capable of running up to eight separate channels, plus the subwoofer (8.1).




7.1: Seven channels of surround sound speakers plus a sub-woofer (the “.1”). Just a couple higher quality surround sound formats have this many channels. For home, it is the Dolby THX EX and for professional theatres, it is Dolby Digital EX, DTS and Sony’s system. The 7.1 version of surround adds two channels of rear surround to be placed behind the audience to the more usual 5.1 system. 7.1 systems include, in professional cinemas DOLBY DIGITAL EX (and the THX EX version), DTS ES, and Sony’s SDDS. Note that Sony’s SDDS is for professional theatres only and it is actually capable of 8 channels plus subwoofers - it includes two extra speakers up front, behind the screen. In consumer home installations, only under Dolby’s “THX Surround EX” name will there be the 2 rear channels.


16 x 9 FORMAT:    The aspect ratio (width:      height) used for most Digital TV display formats including all HDTV and some Standard Definition DTV formats. A standard definition TV format for displaying any widescreen movie aspect ratio greater than or equal to 16:9 (1.78:1) on a 16:9 aspect ratio display. Black horizontal stripes are added to the top and bottom of the active picture area to fill out a 16:9 display. The 16:9 display area utilises 720x480 pixels to provide 33% more vertical resolution than the 4:3 Letterbox format.


16mm to 35mm BLOW UP:     An enlargement process where the original 16mm camera negatives for a film originally shot in the 16mm format are “blown up” to 35mm size. In the 35mm size, the film is then processed through the Film Lab lines. The purpose of the enlargement is that the quality of the final 16mm Release Prints are significantly improved in terms of clarity when the film is processed in 35mm then reduced back down to 16mm. The reduction print, after the film is completed through its 35mm production stages, is called the 16mm REDUCTION PRINT.


16mm:   An abbreviation for 16 millimetre. The width of the film picture area of the individual cine film frames of this size. 16mm is a little over half an inch. 


16mm CHECKPRINT: The test print made of the 16mm Internegative used to run final Release Prints.


16mm REDUCTION DUPLICATE NEGATIVE:      This term is sometimes shortened to “16mm redux dup neg”. The “Reduction Duplicate Negative” is the 16mm Internegative that will produce the film’s 16mm release prints. It is a 16mm negative element, an Internegative, made by directly copying the 35mm Interpositive that made the approved 35mm Answer Print.


16mm REDUCTION PRINT:     See 16mm TO 35mm BLOW UP.


20 BIT:  Digital audio equipment that processes (records or plays back) using 20 bits of computer power. It is said to have a resolution of 20 bits. As a comparison, a CD player is a 16 bit device.


24 BIT:  Digital audio equipment that processes (records or plays back) using 24 bits of computer power. It is said to have a resolution of 24 bits. As a comparison, a CD player is a 16 bit device.


24 fps:   (See 24p.)


24p, 24fps Progressive Video Cameras and shooting for films and High Definition Digital Broadcast TV:       Not all video is recorded and played back as interlaced “fields”. While conventional t.v. video has 30 frames per second and uses two fields per frame, only showing half of the picture at one time (called interlaced), 24p video (24 frames per second progressive) does not use interlaced fields. “24p” is a term used regarding a) when video is made to match the exact amount of frames used in the High Definition 24p camera system, where each frame consists of two “segments” of the full image. (Important Note:  Rather than using the word “fields” in 24p camera shooting, progressive image “fields” are called “segments”. This is to differentiate between a conventional interlaced TV picture which has two fields per frame - each field having only half of the lines of resolution; and the 24p system which consists of two segments per each frame - each segment having all the lines of resolution - the full image.) The system shoots video at 24 frames per second. High Definition 24p video cameras electronically capture images in “segments”, not as interlaced fields. These cameras record what is called a “Segmented Frame” (abbreviated sF) in which there are two progressive segments recorded per each frame - in other words the 24p cameras internally record 48 progressive segmented frames per second. The segments are not interlaced. Each sF has all the lines of the High Definition video image - unlike interlaced images which show only half of the picture’s lines at one time. (The engineers at Sony and Panavision designed and built the High Definition camera system using this segmented frame method of recording the image, because it was easier and more practical to execute the design with existing and proven electronic circuitry.)  So, what ends up on the digital video tape or hard disc is a straight 24p image. Thus any output to film or any other 24fps format (such as a DVD) is done at a straight 24 fps frame rate, one for one. Of course, any TV show for broadcast would have to be converted to 30 frames per second, as TVs can’t play 24 fps video, only 30fps - the television standard. However, this conversion is easily done digitally. And what about DVD video discs? Those have to play on home consumer TVs at 30fps too - so how do the 24fps shot films get put onto the DVD? Simple – DVD’s are already 24 frames progressive. What is stored on the DVD disc is a 24p image. It’s the DVD player that converts that to 30 fps for viewing on TV. For DVD’s, MPEG compression is used to transfer the 24p High Definition video signal onto the DVD disc. The MPEG process “looks” at the 24p signal and converts it to the MPEG-compressed 24 fps progressive full frame images that can be stored on a DVD disc. (Films are stored on a DVD at 24 fps progressive video to save space on the DVD disc.) It would take 25% more storage room on the disc to record the film at 30fps.  Therefore, films are stored on DVD disc at 24fps progressive and the DVD player, using MPEG processing, is what converts the pictures to 30 fps for the consumer’s home TV playback.

For more technical information on the Sony Panavision HDW-F900 HDCAM, read on… The HDW-F900 is a Sony Panavision collaboration that can record a 1920X1080 24p signal. This system also has received attention as a potential universal video mastering format. Additionally, the camera records at 23.98p - a relative of the standard interlaced video rate of 29.97 - which resolves some issues with time code and off-line editing systems. The HDW-F900 also handles 25p, which has the same frame rate as the EBU standard. The other choices are 30p, 25i or 30i. The decision to use one frame rate over another depends on whether you decide to record single or double system sound and post workflow. More information about these issues appears at As well, “Plus 8 Video Rental” (310-477-7080) in LA specialises in the 24p HD format for production and “Laser Pacific” (323-462-6266) in Hollywood is a leading HD post production studio. eFilm (323-463-7041) in Hollywood specialises in HD output to film.


25p:       Abbreviation for 25 frames per second progressive scanning as used in EU. The 25 fps frame rate is the standard for EU, UK and other countries using the EBU video standard. (See 24p for detailed information on progressive scanning video cameras.)


60Hz PILOT TONE:    See PILOT TONE.       


70 VOLT:       This is an amount of electrical current used in specialised audio loudspeaker systems that are installed throughout a home or building. It actually carries audio signal to many different locations - for example to the many ceiling speakers in a large shopping mall. The 70 volt signal is generated by the amplifiers for the loudspeakers in the system - that signal is fed to all the speaker locations. 


70 µSEC EQ,  120 µSEC EQ:    These symbols are seen on nearly every cassette recorder and on most cassette packaging. Looking these up in an electronics dictionary is usually pretty dismaying, especially when it is discovered that “µs” is an abbreviation for “microseconds” What exactly does a “microsecond” (one millionth of a second) have to do with playing a cassette tape? First, it is helpful to know that the number of “microseconds of EQ” has to do with how accurately an audio tape recorder records and plays back magnetic tape. The actual technical names for  these settings of “70 and 120 microsecond eq” are “pre-emphasis” (pre-equalisation) and “post-emphasis” (post-equalisation) which are functions that a tape recorder does to magnetic tape during recording and playback.

Pre-equalisation has to do with what sound frequencies the tape recorder’s electronic circuits increase in volume. This increase is done to enable all audible frequencies to be recorded onto the recording tape with equal loudness. The frequencies the tape has trouble recording are boosted in volume by pre-emphasis, so they will be recorded just as loudly as other frequencies the tape is more sensitive to. This enables tape to accurately record all the parts of an audio programme. As a rule of thumb, high frequencies are increased in volume during recording and decreased during playback; while the lows (bass) are left alone in recording and then boosted during playback to make up for the tape not recording them very strongly in the first place. On some cassette decks and tape packaging the labels simply say “Metal Tape” or “Ferric Tape” so one knows to push the buttons on the cassette deck that are so labelled. As for the term “microseconds”, the number of microseconds is simply part of the process that electronic circuits use to perform these pre and post-equalisation functions accurately. Sound frequencies are actually vibrations. “70 microseconds”, “120 microseconds”, etc. is how long the frequencies that need to be boosted take to rise from no volume to their full volume for one single vibration of that frequency. 70 and 120 microseconds are called time constants, because they are standard amounts of time required for the rise of a sound frequency from no volume to its full volume - the very fist impulse of a given sound. (This can be easily displayed on an oscilloscope if you need to get some mass.) The number of “microseconds” seen on a cassette deck or packaging simply expresses at which frequency (denoted by length of time) the electronic circuit starts to raise the volume of those frequencies to help the tape record them. Different types of tape need somewhat different frequencies boosted (equalised) at different amounts. That’s why there are two different settings (120 and 70). Ferric tape requires an EQ boost at 120 µSec, whereas chrome and metal tapes require 70 µs. Each of those settings refers to an exact frequency and an exact amount that frequency is boosted to enable the tape to be recorded and played back so that the listener hears the sound with the correct amounts of low, mid and high frequencies. 120 µs relates to the ferric cassette tape pre-equalisation starting at about 1,300 Hz and gradually increasing in volume as the frequencies get higher in pitch; and 70 µs is for chrome and-or metal cassette tape whose high frequency boost starts at just over 2,000 Hz. Professional audio recording tape and recorders have different EQ curves because they use different tape and they record and play back at different tape speeds (the speed at which the tape is recorded also affects how much EQ is needed for pre-emphasis and post-emphasis).


75 OHM TERMINATOR:     Ohm is a unit of resistance to electrical flow. A terminator is a device you use to end the path of a signal. In video you can sometimes get an overly bright and bad-looking picture on the screen. This is often due to a video cable somewhere on the line that is not connected to anything. In this case the signal has nowhere to go so it flows back into the video cable and the unit that is feeding it, and then interferes with the video picture displayed. To handle this you “terminate” the video routing by connecting a “terminator”. A 75 ohm terminator is a specific type of terminator which has the correct amount of resistance to the flow of the video signal to cause it to stop at the point of termination and not flow back up the line. Many video monitors have a switch on their back panels to add a 75 ohm termination to the signal if needed. There are also video connectors that have this 75 ohms built right into them that you can just plug into a cable.


100 Hz TEST TONE: It is vital in producing an audio programme that the equipment used be tested and adjusted to meet the exact standards required to produce a high-quality product before it is used for the production of that product. Audio technicians and engineers use “test tones” to do these tests and adjustments. When the adjustments are done, the equipment is said to be calibrated. A “100 Hz test tone” is a principal test tone commonly used to calibrate the bass region of equipment (tape recorders, etc.).


192 kHz TWO CHANNEL (stereo): DVD-Audio specification. DVD-Audio discs are capable of storing and playing back stereo (not surround) music or other audio programs that are sampled at 192 kHz.


601 VIDEO:  (Pronounced Six-Oh-One.) This is the industry standard for digital video. It is not the same as High Definition video, although generally the TV-video industry agrees that 601 is the minimum point of video quality that can be considered High Def. The term “601” simply comes from the paragraph number in the International Telecommunications Union (ITU) specifications book published by the video industry. That paragraph (#601) gives the technical specifications for 601 video. Virtually all major studios and broadcasting stations are moving to or have already moved to the 601 format.

For a technical description of 601 video, read on… The 601 standard that was accepted by the ITU was established by the joint efforts of members of both SMPTE and EBU. 601 video is a component serial digital interface (SDI) colour video format in both 525 line (59.94 fields/frame countries - like the USA) and 625 line (50 fields/frame countries - like EU) systems. Its digital sampling frequency is 13.5 Megahertz for luminance (brightness) and 6.75 Megahertz for chrominance (colour). It will do 8 or 10 bit digitising. It samples at 4:2:2 meaning that for every 4 luminance samples, it takes 2 samples of (R-Y) and two samples of (B-Y). 


720i, 720p:   See PROGRESSIVE SCAN.


1,000 Hz TEST TONE: It is vital in producing an audio program that the equipment used be tested and adjusted to meet the exact standards required to produce a high-quality product before it is used for the production of that product. Audio technicians and engineers use “test tones” to do these tests and adjustments. When the adjustments are done, the equipment is said to be calibrated. A “1,000 Hz test tone” is the principal test tone commonly used to calibrate the volume level of equipment (tape recorders, etc.).


1000 ZXL:  See NAKA 1000 ZXL.     


1630:     An older Sony digital video format used extensively for mastering CD’s. Though the machines are no longer made by Sony, it is still a very common format used to send to CD duplication plants. It uses a large sized videotape and is capable of high quality.


2496, 24-96:        A SADiE model number. See SADiE.


16,000 Hz TEST TONE:     It is vital in producing an audio programme that the equipment used be tested and adjusted to meet the exact standards required to produce a high-quality product before it is used for the production of that product. Audio technicians and engineers use “test tones” to do these tests and adjustments. When the adjustments are done, the equipment is said to be calibrated. A “16,000 Hz test tone” is a principal test tone commonly used to calibrate the high frequency region of equipment.