Important technical terms of the AV- and home cinema world

11.11.2003, written by Carsten Rampacher

Below please find a comprehensive but not exhaustive summary of some important technical terms used in the audio-,video and home cinema world, in alphabetical order. The explanations have consciously been written down in a brief manner in order to provide with an overall view. Therefore, for those who are interested in finding out what lies behind all these technical terms, that the dealer employs during a sales conversation, can inform themselves before buying a relevant device. 

• A/D-converter: Analogue/digital-converter, which is transforming analogue data into digital data. Common A/D-converter: 96 kHz/24-bits, 192 kHz/24-bits
• Active subwoofer: Loudspeakers for bass reproduction with built-in amplifier
• Active loudspeaker: Loudspeaker with built-in amplifier. Can be connected directly to a pre-amplifier or an external decoder, on condition that the box disposes of Cinch-inputs
• Anamorphic Widescreen: During the mastering of the DVD the picture will be recorded by a horizontally stretched master or later on electronically stretched and transferred to DVD with a resolution of 576 horizontal lines (PAL) respectively 480 lines (NTSC). Advantage: All 576/480 lines can be used. The picture quality is considerably better. The small distance of lines ensures that the line structure does not disturb the quality of the picture. In order to be in a position to use the advantage of the high picture resolution effectively, it is important that the DVD-player is able to correctly output the anamorphic picture of the DVD. Each player provides a menu screen in the set-up available, where the format of the picture can be adjusted. If a 16:9-television set is used, the corresponding adjustment has to be arranged there, too. Provided that the DVD player has been adjusted to 4:3 the appliance transforms the anamorphic picture for the presentation on a 4:3 television set. The procedure is as follows: The video electronics of the DVD-player removes each fourth picture line. Finally the electronics re-inserts black bars on the upper as well as the lower part of the picture. The final result of this procedure is a normal letterbox-picture
• Artefacts: Image interference which can be taken from small block patterns, which can result in a qualitatively bad MPEG2-video compression at the DVD – to sum up we are talking about compression artefacts in this matter
• AV-amplifier: Consisting of a pre-amplifier-section and several integrated amplifiers (e.g. 5, 6 or 7) for the home cinema operation. An AV-receiver disposes of a built-in tuner additionally to an AV-amplifier
• Back surround loudspeakers: Common at extended surround systems. An additional box or two additional boxes are spatially positioned behind the left/right surround-loudspeakers
• Bass management (at AV-receivers/amplifiers, DVD-players with internal decoder): Permanently ensures an optimum of bass quality by means of a corresponding signal bypass depending on the size of the loudspeaker and the use or non-use of an active subwoofer
• Bitrate: Bitrate like e.g. of a DVD. Permits adjustments to the strength of the picture- and/or sound compression. 
• Bitstream: Bitstream at the Dolby Digital-/DTS-transfer on the digital way from the DVD-player to the AV-receiver or amplifier.
• D/A-converter: Digital-/Analogue-converter, which is able to transform a digital signal into an analogue signal. Common D/A-converter: 96 kHz/24-bits, 192 kHz/24-bits.
  Decoder: Necessary for the decoding of the DD- or DTS-bit stream. The task of the decoder is to make the bit-stream useable for further processing. Also DVD Audio-, SACD- or MP3-signals have to be decoded. A DD/DTS-decoder can be positioned into a DVD-player or into the AV-receiver/-amplifier. Separate DD/DTS-decoder are rarely to be found.
• Digital input/-output: Responsible for the digital transfer of data. The "classical" variants: 1. Optical or TOS-Link digital input-/output. Here the electrical signal is converted into an optical signal for the transfer. On the target appliance again the conversion into an electrical signal is carried out. Coaxial or electrical input/-output: Signal transfer on the electrical way. At these classical variants maximum data in the 96 kHz/24-bits 2-channel-format can be transferred - however not more. A bigger data quantity can be transferred by means of new, digital high-speed- interfaces like “i.link” or “DenonLink”. 
• Dipole-loudspeakers: A loudspeaker-box, emitting the sound in a certain radiation angle forwards and backwards, for the production of a diffuse sound picture. Common working principle at loudspeakers for the surround- and back-surround-operation. 
• Direct-emitting loudspeaker: Loudspeaker-box, directly emitting the sound in a certain radiation angle forwards in the direction of the listener.
• Dolby Digital: Digital multi-channel-sound-compression-procedure of the Dolby Laboratories.
• Dolby Digital 5.1: Dolby Digital in "classical" channel-arrangement: Two discrete full-frequency channels for the main loudspeakers, a discrete full-frequency-channel for the centre, two discrete full-frequency-channels for the surround loudspeakers and a bass channel limited to the deep-frequency-range (LFE-channel), +10 dB louder recorded than the remaining channels.
• Dolby Digital 5.1 EX: Dolby Digital 5.1 with an additional back surround channel, produced by means of a matrix (the back surround channel is no discrete full-frequency channel!)
• Dolby Pro Logic: Analogue, matrix-based four-channel-surround-encoding-/decoding procedure. Only frequency-limited monaural-signal for surround.
• Dolby Pro Logic II: Further developed decoders are e.g. working without frequency limiting and with a better channel separation for the surround-range (no cross-talking at the surround channels). With different programmes for the music-and movie mode.
• DLP-projector: Video projector working according to the Digital Light Processing-principle, developed by Texas Instruments. In contrast to LCD-projectors no LCD-
  panels are fluoroscopied, but the picture is reflected by means of small mirrors. The result is essentially a higher lighting efficiency as at a LCD - projector. In the interior part one to three mirror panels can be found, consisting of hundred thousands of microscopically small mirrors, which can all be individually selected. The pictures are however bunched to a single picture and are leaving the projector by a single zoom objective.
• DSP/DSP-programming/DSP-techniques: Digital sound programmes, programmed more or less high-graded, cause an increase in listening pleasure. Mostly these programmes are intended for a special use (e.g. DSP-programme: "Jazz", "Stadium" or "Concert Hall". In practice disadvantages in sound are usually arising from insufficient programming. Outstandingly programmed DSP’s can however achieve a considerable improvement in sound quality.
• DTS: Digital Theatre System: Data compression procedure for the home cinema range, competition to Dolby Digital. Is working with other encoding.
• DTS 5.1: DTS in the "classical" channel-arrangement: Two discrete full-frequency-channels for the main loudspeakers, a discrete full-frequency-channel for the centre, two discrete full-frequency-channels for the surround loudspeakers and a bass channel limited to the deep-frequency-range. 
• DTS ES compatible 6.1: Extended surround-format. Here the AV-receiver- or amplifier-manufacturer is constructing their own matrix, not officially licensed by DTS, for the back surround range. Its penetration of the market is still very small.
• DTS ES Discrete 6.1: Extended surround-format. Here you can find an additional discrete full-frequency channel (transmission from 20 Hz up to 20 kHz) for the back surround range.
• DTS ES Matrix 6.1: Extended surround-format. Here you can find an improved matrix with more highly developed channel separation for the back surround-range. 
• DTS 96/24: Sound format for DTS-DVD’s, 96 kHz/24-bits. Increased sound quality with respect to the usually common 48/24-bit-DVD.
• DTS Neo:6: Surround-producing system with a high-graded matrix for the surround-range. 2 programmes for music and movie operation. On the market for a longer time, therefore not completely “up to date" with regard to the sound-performance.
• DVD: Digital Versatile Disc
• DVD Video: The format of movie-DVD’s
• DVD Audio: High-quality format, in practice only used for sound information, with no loss of data compression according to the MLP (Meridian Lossless Packing)-procedure. Typical configurations:96 kHz/24-bits 6-channel or 192 kHz/24-bits- 2-channel
• DVD-RAM/DVD-R/DVD-RW/DVD+R/DVD+RW: Different formats for single or repeatedly recordable DVD’s. Up to this point of time no format has definitely been carried through. Single recordable DVD-R’s are mostly running in each kind of DVD-player.
• DVI: Digital Visual Interface. Thanks to DVI it is now possible to transfer digital video signals without a loss-making conversion into an analogue signal from the DVD-player. The picture reproduction appliance then requires a DVI-input, in order to be able to receive the digital signals directly. For example a DLP-beamer with DVI-input is directly further processing the digital data, so that no single loss-making conversion from analogue into digital data or from digital into analogue data is to be found on the complete signal way. This leads to an increase in picture quality. 
• Efficiency (please also have a look at „sound pressure level“): The relation between supplied electrical performance and released acoustical performance describes the efficiency. The electrical performance (in watts), which a loudspeaker receives, is only partly transformed, as already described above, into sound. The biggest part is converted into heat or gets lost due to friction losses. The efficiency is indicated in decibel (dB), measured in 1 metre distance and at 1 watt input performance. In practice the efficiency of a loudspeaker is quite important as at a given performance input or load the maximum volume of a loudspeaker depends of its efficiency. 
• Encoder: Produces e.g. a DD-, DTS- or DVD Audio-codec.
• FBAS-Composite: The kind of connection, which each beamer, display or TV should accept. Disadvantage: At Composite the colour- as well as brightness part of the picture signal are not transferred separately, which leads to considerable deficits in the picture quality with regard to other picture signal transmission modes (please compare component-, S-video- or RGB-connection).
• Edge steepness: Important in relation to the frequency separating filter. When achieving their cut-off frequency the frequency-separating filter is damping the signal components, which are not shifted through the frequency-separating filter. The intensity of the damping depends on the corresponding filter design. Each high- or low-pass filter consists of different units, which number fixes the order as well as the strength of the signal damping, the edge steepness. Each so-called complex construction element (inductions, capacities) intensifies the damping by 6 dB per octave, which means that a filter 1. order (without any pre-launched other unit) possesses of an edge steepness of 6 dB per octave, a filter 2. order then logically disposes of an edge steepness of 12 dB per octave.
• i.link: Trade name of IEE1394 Firewire. Digital high-speed interface, suitable for the transfer of extended data quantity. By means of i.link also DVD audio- and/or SACD-signals can be conducted out of the DVD-player. Prerequisite is a i.link-capable AV-amplifier. 
• Impedance: Current resistor indicated in the unit “ohms”. At loudspeakers it can be taken from the ohms-value how strong are the loudspeaker loads from the amplifier depending on its output impedance (internal resistance, indicates the current resistance, situated on the loudspeaker output of the amplifier). An amplifier, disposing of e.g. an output impedance of 8 ohms, is very strongly loaded e.g. by loudspeakers with an impedance of only 2 ohms. Therefore amplifiers with a low output impedance can be seen as an advantage as these amplifiers can also supply loudspeakers with 2- or 4-ohms with high current intensities. Special requirements to the high-current capability of the amplifier are demanded e.g by the THX Ultra standard. Common impedance values are 4, 6 or 8 ohms. 
• Interlaced- or interlacing procedure: Here alternately the straight and the odd picture lines are selected from left to right. Each frame by frame consists of two fields: The picture output appliance, which is working in this way (hitherto television set) not only shows the complete picture, but first of all a field with the straight lines and then a second field with the odd picture lines. However due to the quickness of this procedure the viewer hardly realises that the picture is consisting of 2 fields. But: Especially at extended picture diagonals the easy visible lines structure of an interlaced picture disturbs. 
• Component output (so-called YUV-output): In the YUV-signal format there is also the picture on the DVD. This signal consists of colour difference signals. The connection via YUV enables an outstanding picture quality and realises the possibility for progressive scan-picture signal processing. Three cinch cables, especially provided for video use, consist of a YUV-connection. 
• Time alignment (also Delay Time): Its task is to ensure that the sound signal (provided that the single boxes are positioned at a different distance from the testing room) arrives at each loudspeaker at the same time at 5.1/6.1/7.1-loudspeaker systems.
• Layer change: A DVD-9 (the most frequently used DVD for the storage of movies at the present point of time) is a DVD, at which two layers have been positioned on one single DVD-surface. After having read out the first layer completely by the laser of the DVD-player, the laser has to re-focus in order to be able to read the second layer. This layer change can be evident on some DVD-players due to a picture and sound break-down. Above all this is the case when the layer change on the DVD has been carried out unfavourably (e.g. during a scene and not at the end of a scene). It depends on the corresponding DVD-player-variant how long the break-down of the picture as well as the sound takes place. Provided that it is demanded to make the layer change of the hardware more or less invisible, the DVD-player requires a sufficiently dimensioned buffer memory (for the data storage during re-focusing process and a disk drive with a high readout speed. 
• LCD-Projector: Kind of projector, which is fluoroscopied by strong halogen lamps at the LCD-panels. Finally the picture is bundled together and leaves the projector by a single zoom lens.
• Linedoubler: Appliance which was built in externally or in the video-projector, which doubles the number of lines of the supplied picture signal and which therefore improves the picture quality. 
• Maximum load / Music load / Short-term power: Transcribes the corresponding short-term (in maximum 2 seconds) impulse loading capacity, which the loudspeaker can handle without any damage of the material. The reproduction quality shall not be disturbed in a sustained manner. 
• MP3: Procedure, which very strongly compresses audio data, which means that on one CD numerous MP3-tracks can be stored. In order to facilitate the clarity, a structure of files can be prepared when producing MP3-discs. Almost all DVD-players of the actual generation on the German market are able to read MP3-CD’s. Only at the versatile MP3- can additional functions and important differences be found.
• Nominal load: The nominal load of the loudspeakers, indicated in watts, indicates the maximum electrical performance of the loudspeaker during steady operation. The nominal load has been fixed exactly according to DIN-standard (Germany). With a special noise signal in 1. minute on-/2 minutes off – time rhythm during a period of 300 hours the nominal load is determined. The rhythm of the noise signal is intended to simulate a typical music programme. High frequencies are to be found far more seldom than the deep ones. 
• Octave: The musical distance between the frequency and the doubled frequency. The response area of the human hearing, where sounds can be perceived, is approximately between 20 Hz and 20 kHz (talking about a baby it is up to 20 kHz, at an adult it is up to 16 kHz) and therefore it contains 10,5 octaves. 
• PCM: Pulse Code Modulation. At certain times the PCM-procedure detects the momentary situation of the analogue output signal – therefore no 1:1-taking over of the original signal, which leads to the fact that the signal can’t be reproduced completely unaffected and true to the original. However the time distances, when the detection of the analogue signal is carried out, can be selected as short or as long as required, which leads to the possibility of a more and more precise reproduction of the analogue output signal. The CD uses pure PCM-samples. Besides this PCM-samples are the basis for the DD- and DTS-as well as DVD Audio-encoding.
• Pixel: A small single picture element. 
• Pixel Errors: Can e.g. arise at LCD-projectors and LCD-display screens. One or more pixels are wrong with respect to the colour (e.g. the picture is blue, however 2 pixels illuminate in red).
• Pre-Outs: Outputs on the AV-receiver or AV-amplifier, which can be connected to external amplifiers.
• Progressive Scan: On the DVD the movie has been stored in individual full-frames (on DVDs with video material in the interlaced-procedure). Progressive scan enables picture output out of the DVD-player in the full-frame procedure (via component or VGA-output).
• Noise filter: Filter integrated into DVD-players, the task of which is to decrease picture noises in general. In most cases it can be switched in several steps. In order to be able to fight against individual kinds of picture noises well-aimed, high-graded DVD-players still possess more special filters e.g. against block noise or so-called "Moskito Noise"
• RGB: A DVD-player, connected via RGB, presents the picture in the same way as the picture tube in the television set or CRT-projector assembles it (in the three basic colours “red, green and blue”). Therefore the picture can be directly transferred without any extensive alternative routing by means of the corresponding output (RGB-switched Scart-jack) directly to the picture output appliance.
• CRT-projector: The "classical" kind of beamer. Three separate picture tubes (red, green, blue) are producing the picture. Important at the picture adjustment is the convergence of the colours.
• SACD: High-quality-medium for audio data. Is working together with the DSD (Direct Stream Digital)-procedure. Initiated by: Philips and Sony among others.
• Sound pressure level: Describes the loudness level, produced by the loudspeakers. The SPL is dimensioned in decibel (dB) at 1 watt input performance with a distance of 1 metre.
• Smart Circle Surround/Circle Surround II: Surround-producing programme, at Circle Surround II with an improved matrix, movie- and music programme, the bass amplifier "TruBass" and different adjustment possibilities. 
• Subwoofer: Bass loudspeaker, active or passive. Common with surround equipment: The active subwoofer with integrated amplifier. 
• Subwoofer-cross-over-frequency: Determines at which frequency the subwoofer takes over bass reproduction. 
• SVCD: Super Video CD. Offers a better picture quality than VCD. An extreme variety of creation possibilities. 
• S-video: Here the luminance- and the chrominance components of the picture are separately transferred. At DVD-players the Scart jack is able to output s-video-signals in many cases, otherwise a so-called Hosiden-jack is available for the output of this kind of signal. 
• Partly active loudspeaker: Loudspeaker-box, which e.g. disposes of a passive tweeter- and midrange loudspeaker and an active bass module. 
• Test pictures: Special pictures, the purpose of which is to test the picture quality and the quality of the picture adjustment at picture output appliances and at the DVD-player. 
• Test tone: Sound signal which each kind of loudspeaker of a surround equipment outputs at the calibration. A surround equipment has been correctly adjusted when each loudspeaker seems to be as loud as the other one at the listener’s place. The one who does not want to rely on the test tone generator, built in the AV-receiver/-amplifier, has got the possibility to line-up the equipment by means of a decibel meter. 
• THX: Procedure, developed by Lucasfilm, to increase the acoustical performance of cinemas. Not every cinema received the permission to bear this THX-symbol. It still has to become officially THX-licensed. 
• THX Home: Optimises the acoustical performance of movies by post-processing different parameters strictly according to the conditions of a home cinema (e.g less boxes than in the cinema, necessity of height-adjustment) by means of a separate processor as per the original decoding. Products which shall be according to the THX-guidelines are checked by THX and then licensed. There are THX-licensed loudspeakers, DVD-players, AV-amplifiers-/receivers and corresponding software. 
  THX Select: "Simple" THX-standard with lower demands to the performance of the equipment. Suitable for small and middle-size rooms. 
• THX Surround EX: Extended surround-sound standard of THX, stipulated are 2 loudspeakers for the back-surround-operation. 
• THX Ultra: THX-standard with higher demands to the performance of the equipment. Foreseen for extensive and very extensive room sizes.
• THX Ultra II: Newest THX-standard for 7.1-systems. With 2 programmes for music- as well as movie reproduction. Suitable for the accurate reproduction of 5.1-material by means of a 7.1-configuration. Contained in the THX Ultra II standard are still more stronger demands to the active subwoofer.
• Twin Laser Pickup: Separate laser units at DVD-players for the CD- and DVD-operation.
• Video D/A-converter (also video DAC): Converts the digital video data of the DVD into analogue data. Common video D/A-converter: 10 bits/27 MHz, 10 bits/54 MHz, 12 bits/108 MHz
• Video-equalizer (short-called video-EQ): In a lot of cases a useful feature in the DVD-player, which enables individual picture adjustment. 
• Video-signal converter: More and more AV-amplifiers-/receivers are consisting of this feature. A video-signal converter is e.g. able to convert a S-video- into a YUV-signal or a FBAS- into a S-video-signal. 
• Zoom-function: At DVD-players there is often the possibility to extend picture cutouts of a DVD by means of a zoom-function.

HOME > HARDWARE-TESTS > ZURÜCK <