Copyright Michael Karbo, Denmark, Europe.


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    Chapter 32. A glossary

    Here are explanations of a handful of the computer terms I have used in the booklet.

    ASIO. Audio Stream Input Output. A standard developed by the company Steinberg, which ensures minimal latency (delay) in audio processing. The sound card Audigy2 Platinum eX can, for example, record music on six ASIO channels at the same time.

    Bit rate. The amount of data per second (measured in bits), which a certain audio or video format is encoded with. A Super Video CD can, for example, be encoded with a bit rate of between 2000 and 2500 kbits/second.

    Band width. The amount of data, which can be transmitted per unit of time between two devices (e.g. between a modem and a web server, or between a hard disk and RAM). See also Bit rate.

    Codec. A digital ”mechanism”, which can encode and decode data. Typically a piece of software, which can compress and decompress audio or video data according to certain algorithms.

    Dolby Digital 5.1. Multichannel audio format, which uses up to 6 loudspeakers: Two front channels, two back channels (surround channels) plus a centre channel. That was 5 channels, which leaves 1 channel, which is a joint effects/subwoofer channel. The soundtrack of every DVD contains sound tracks in the format Dolby Digital, but it can also be in mono (Dolby Digital 1.0) or ordinary stereo (Dolby Digital 2.0). Also used in Sony Playstation2.

    Dolby Digital EX. Dolby Digital Surround EX is an extension of the Dolby Digital 5.1 format. A centre surround channel has been added, which is made up from the signals, which are already found in the left and the right surround channels. So Dolby Digital EX is a 6.1 surround sound system.

    Dolby Prologic/Surround. Older multi-channel audio format, where the back channels are in mono.

    DTS. Digital Theater System. A digital audio format, which is found in certain DVDs. Found in the 5.1 and 6.1 versions. In contrast with Dolby Digital, the DTS soundtrack cannot be connected to a television; this requires an amplifier with a DTS decoder built in. The DTS audio is less compressed than in Dolby Digital. There is also a 20 bits sampling instead of 16 bits. Which produces a superior audio quality – theoretically anyway. See www.dtsonline.com.

    HDTV. High Definition TV. Standard for digital TV transmission, which works with high resolution.

    Hi-fi. High Fidelity. Nearest meaning is ”high credibility”. The term is especially used for stereo systems of high quality, which can reproduce music almost perfectly.

    MLP. Meridian Lossless Packing. Format, which compresses sound data circa 1:2 without loss. Used for audio recordings with the format DVD Audio.

    PCM. Pulse Code Modulation. A system for digitizing sound by sampling. Used in almost every form for electronic / digitised sound recording and reproduction. The pure ”raw” sound data, which comes out of the PCM sampling, is also called wave data. When wave data is sent into a D/A converter then it is converted into electric waves, which are amplified and sent out into the loud speakers.

    Progressive scan. A system found in the better DVD players. Analog video signals are further processed so that screen updating occurs without interlacing.

    RMS. Root Main Square. The maximum effect (watt) that can be sent from an amplifier to a loud speaker.

    SoundFont. A system, where sampled sound, installed as files on a hard disk can be worked with in MIDI settings. The system is designed for maximum flexibility.
    See also www.soundfont.com.

    S/PDIF. Sony/Philips Digital Interface Format. A standard, which describes transmission of digital audio data between two devices. Many formats can be transferred, like, for example, uncompressed PCM sound or compressed surround sound in formats like Dolby Digital or DTS. The transmission takes place through different sorts of cables, e.g. RCA-coax or TOSLink.

    Streaming media. The term for the transmission of audio and video recordings over a network (the Internet), where the files’ data can be played back at the same time as it is transmitted. Play back starts after the transmission of a small portion of the data; the rest is transmitted at the same time as it is played. Windows Media, Quick­Time and Real are the three most known formats for video/audio streaming.

    Surround sound. Common term for sound systems, where more sound channels are used than with stereo. The most widespread system is 5.1 sound, but there are a lot of variants.

    THX. This sound system is not a format but rather a standard of quality, which has been developed by George Lucas (from the Star Wars films). Producers can send equipment for testing to Mr. Lucas, who then supremely decides if the equipment lives up to THX or not.

    TOSLink. Toshiba Link. An optical cable, which transmits digital sound data via red LED light impulses. The cables end up in square plugs, which transmit sound information. These plugs are kept closed with small plastic caps, which protect them from dirt.

    TruSurround. A patented system developed by the company SRS Labs. A DVD’s multi-channel sound can be re-coded into a normal stereo sound with TruSurround, which at the same time gives the illusion of surround sound. Listeners experience the sound as if it is coming from different places in the room.

    Links

    Use these links to web pages, which deal with audio and video. There are lots of articles to be fetched, but all of them are in English.

    www.digit-life.com
    www.divx-digest.com
    www.dvdrhelp.com
    www.stereotimes.com
    www.techtv.com
    www.vcdhelp.com

    Afterword

    I hope you have learnt a lot from reading this booklet. It has been intriguing and very challenging to write. I was very surprised myself at how interesting the subjects of audio and video proved to be. We will be hearing a lot more about all these formats and will be seeing many new in the coming years. Have a good time!


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