CD Basics

 CD Audio










Glossary title graphic

5.1 - AVI 

Glossary of CD and DVD related technical terms and abbreviations in alphabetical order.

3/2 Pulldown: A technique (3/2 pulldown) for converting 24 fps film to 30 fps NTSC video by adding fields.

4C Entity: The group of companies (IBM, Intel, MEI and Toshiba) that developed copy protection for DVD etc. The 4C Entity licenses CPPM, CPRM and Verance watermarking.

5.1: A surround sound format comprising 5 full bandwidth channel (left, centre, right, left surround and right surround) plus a low frequency effects channel (LFE).

a_characters: The ISO 9660 character set used in the Volume Descriptors and comprising 'A' to 'Z', '0' to '9', space plus symbols.
A-Time: Absolute-timecode for CDs, contained in the subcode Q-channel as minutes, seconds and frames measured from the beginning of the disc.

AC-3: Dolby's 5.1 channel surround sound digital audio system, specified for DVD-Video discs. It is now referred to as Dolby Digital.

ACP: Macrovision’s Analogue Copy Protection system for DVD-Video, developed and patented by Macrovision. It comprises two elements: Automatic Gain Control (AGC) and Colorstripe. ACP is supported by most DVD players, and causes VCRs to make distorted copies, with no entertainment value.

ADPCM: Adaptive Differential Pulse Code Modulation is an audio encoding compression technique that encodes the difference between the predicted value of the signal instead of the absolute value of the original waveform so that the compression efficiency is improved. This difference is usually small and can thus be encoded in fewer bits than the sample itself. ADPCM is used in PC sound cards, on CD-i and CD-ROM XA discs.

AFM: Atomic Force Microscopy, a technique for measuring the topology of 'bumps' on a CD or DVD stamper, to ensure that the mastering and electrofoming processes are creating stampers that will result in good pit geometry.

Ag: The chemical symbol for Silver, used as the reflective layer of CD-R discs (as a replacement for gold). A silver alloy is also used as the semi-reflective layers on dual layer DVD discs.

AGC: Automatic Gain Control, which is used in Macrovision’s Analogue Copy Protection (ACP), which causes VCRs to distort the video so that the copy is unviewable.

Al: The chemical symbol for Aluminium, used for the reflective layer on CD and DVD discs.

Album: One side of a DVD-Audio disc, containing Groups and Tracks.

Album ID: The unique identifier for a DVD-Audio album, necessary for a CPPM-protected disc.

Aliasing: A form of image distortion associated with signal sampling at low resolutions. The result is that diagonal lines appear stepped (like a staircase).

Amaray Case: A plastic clamshell type case designed for DVD discs to differentiate them from CDs and to protect them. It is similar to clamshell cases used for VHS cassettes but is wider and thinner.

Analogue: The representation of numerical values by physical variables such as voltage, current, etc. Analogue devices are characterized by dials and sliding mechanisms.

Analogue Video: A video signal that represents an infinite number of smooth gradations between given video levels. By contrast, a digital video signal assigns a finite set of levels. Analogue signals are prone to the effects of noise, but digital signals are less affected by noise.

Anamorphic: A term used to describe the representation of a wide-screen video image by squeezing it horizontally to fit into a conventional 4:3 aspect ratio for purposes of storage and transmission. The image is stretched back to wide screen (usually 16:9) before being displayed.

Angles: On a DVD-Video disc up to 9 camera angles can be used so that different views of a scene can be included and the user is able to switch from one to another while watching the video sequence. An example is a pop concert, where the viewer can choose which performer to view and change the view (angle) during the video.

Anti-aliasing: A form of interpolation used when combining images to provide a smooth transition between pixels. A good example is text over a plain or textured background. This will require the use of additional shades of colour and intensity between the foreground text colour and the background.

AOB: Audio Object, a file on a DVD-Audio disc containing the audio information. AOBs are equivalent to VOBs used on DVD-Video discs.

AOD: Advanced Optical Disc, a new format being proposed by Toshiba and NEC as the next generation DVD. AOD discs would use a blue laser to read them and can hold 15 GB of data per side on a pre-recorded disc, but 20 GB on a re-writable version. The DVD Forum is studying both AOD and Blu-ray as contenders for a new HD-DVD format.

APRS: Association of Professional Recording Services. The APRS is a UK organisation that promotes the highest standards of professionalism and quality within the audio industry. Its members are recording studios, post-production houses, mastering, replication, pressing and duplicating facilities, and providers of education and training, as well as audio engineers, manufacturers, suppliers, and consultants. Its primary aim is to develop and maintain excellence at all levels within the audio industry of the United Kingdom. (see

APS: Analogue Protection System, Macrovision's copy protection system for DVD-Video that distorts the video output so that after being recorded to VHS tape and then played back the video is unwatchable.

Artefact: An unintended, unwanted visual aberration in a video image

ASCII: American Standard Code for Information Interchange for representing text characters. The ASCII character set is the basic set used by computers for many years.
Aspect Ratio: The relationship of width and height of pixels in an image.

ASV: Audio Still Video, a still image on a DVD-Audio disc. Up to 20 high quality ASVs can be loaded into the player memory before the audio is played and so can be replaced between tracks where an audio mute is acceptable.

ATRAC: Adaptive Transform Acoustic Coding, a method to compress audio data and used in the MiniDisc.

Au: The chemical symbol for Gold, used for the semi-reflective layer (Layer 0) of dual layer DVD-9 discs.

Authoring System: Software that helps developers design interactive courseware easily, without the painstaking detail of computer programming.

Autoplay: A feature (eg within Windows 95 or 98) for example allowing a CD-ROM disc to play automatically when inserted.




5.1 - AVI

B-frame - Byte 

Caddy - CYMK


E22 - Fulfilment

Gamma - ITTS

Jewel - Lumin


OD - Push/Pull

Q - Runlength


Table - YUV


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