A

ADC - Analog to Digital converter. This device converts analog signals into a digital form. Digital devices, such as computers and digital comcorders, that can accept analog audio or video contain an ADC in order to record analog signals onto digital media.

AGC - Auto Gain Control. This is electronic circuitry contained in many video and audio devices that is designed to even out signals going into or coming out of that device. Low signals are boosted and high signals are lowered to a preset level.

ANALOG - This refers to a video or audio signal consisting of voltages or waves, rather than 1's and 0's like a digital source.

ASPECT RATIO - This refers to a number of units wide vs. a number of units high in regards to a film or television picture. For example, an standard definition (SD) television screen is 4 units wide and three units high, or 4:3. An HDTV screen is 16 units wide to 9 units high, or 16:9. Each ratio holds true no matter how large a screen is. Films often us ratios such as 1.85:1 or 2.35:1, which are the wide aspect ratios you usually see in theaters.

AUDIO DUBBING - This allows replacing the original audio track without affecting the corresponding video track. Some camcorders and VCRs support this feature.

AUDIO EDIT - Similar to an audio dub, but allows more control over levels and overall sound of the audio. In addition, while audio dubbing usually replaces the entire audio track, an audio edit can replace or add to a portion or all of the existing audio. An audio edit is usually done using a video or audio editing system, rather than directly through a camcorder or VCR.

B

BALANCED SIGNAL - This is a method of avoiding external noise in a cable by essentially sending a two identical signals down it at the same time, but out of phase of each other. Signal processors at each end put everything back in phase. The idea is that only the out of phase signal will be relayed. External noise won't be out of phase and is ignored.

BETA - This was a video format that competed with VHS. It failed when the market leaned toward VHS.

BETACAM - A professional video format used by many TV companies. It is standard definition and comes in both digital and analog forms. Like many pro formats, it offers both regular and mini sized cassettes. The mini versions are meant to be used in field cameras. There small size means tape lengths are shorter. It is slowly being replaced by High Definition video formats.

BETAMAX - Betamax was a competing format for VHS created by Sony. VHS eventually won the format war and Betamax all but disappeared from the marketplace (though tapes still have limited availability).

BIT RATE - This refers to the amount of data transferred each second. In video, the more data, the more smoothly and cleanly it plays back. Bit Rate and resolution (the number of screen pixels per frame of video) work together to produce quality video. In both cases, the higher the better. If one is low while the other is high, video quality will still suffer.

CCD - Charge Coupled Device. This is the sensor inside a camera that collects light entering through the lens and creates the electronic image. This image is then transferred to tape.

CLIPPING - Refers to the point at which a signal level is too great for equipment to handle. This can be audio that is too loud or video that is too bright. Audio will sound distorted while video will tend to "glow" in the brightest portions.

COMB FILTER - An electronic method of filter some frequencies while passing others along. TVs use this method to remove interference and other signal problems from the video image.