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What is DVD?
A DVD (digital versatile disc) is a storage medium that is almost universally usable. DVDs provide superior image and audio quality, are easy to handle and, above all, interactive. With DVDs, viewers can help determine the program - for example, by retrieving different segments on the DVD directly using one or more menus and without rewinding, fast-forwarding or waiting.
What is DVD Authoring?
Authoring is the designing of an interactive DVD with selection menus, images, sound and graphics.
What is an Artifact?
In video technology, this term describes visible, disturbing defects in pictures caused by technical limitation. Oftentimes they cannot be described by technical measured variables. Noise signals at object edges or undesired contours in picture sections often occur in picture areas in which smooth transitions should be displayed. Artefacts also often occur in cases where the amount of video data is considerably decreased as a result of high COMPRESSION RATES. The visible and typical "building block effects" of highly compressed video signals are called artefacts.
What is Compression?
Digitization of large quantities of video and film material creates large amounts of data. To be able to process these data with commonly applied computer technology, the data quantities are being reduced by means of compression. With the help of different calculation operations, one tries to recognize the irrelevant or least relevant information within a picture in order to leave it out. In the case of mild compression, all original data can be restored from the compressed data stream. In the case of stronger compression, picture information is irretrievably lost. The data quantity results in a loss of picture quality. There are several different compression methods with different efficiency levels. The goal is always to reach an image impression as natural as possible with a minimum amount of data. Common compression methods are MPEG, JPEG, M-JPEG, DV.
What is Digital?
In simple terms, one could say that digital processes only know two states: 1 or 0, yes or no. Continuous phenomena like curves are subdivided into sections and disaggregated into single events. Digital technology processes and transmits data as information packages. In contrast to analog systems, digital data can be identically presented and stored (light, electricity, characters, magnetic particles) in different media (data carriers). The accuracy of presentation (resolution) is independent of the medium. A large quantity of data is necessary for highquality signal processing. Since digital technology uses mere numerical values, the large amount of data can be reduced with the help of suitable mathematical methods (COMPRESSION).
What is DVD - Video?
Digital Versatile Disc-Video. One possible DVD FORMAT. Common especially in the field of home entertainment with movies as content. According to plans, the DVD Video will replace the recorded VHS tape in the near future. Compared with a VHS cassette, the DVD not only offers enhanced image quality, but also several additional features: the sound on a DVD-Video can be set to different languages, and subtitles in even more dif ferent languages can be integrated. The same video Sequence can be located on the disk in different camera positions. The user can then select the desired sound, fade-in subtitles and switch between the different camera positions. All these functions can be realized, but are only partly used in the case of current DVDs. In the case of DVD-Video, the picture material is coded according to MPEG-2 (MP@ML), thus realizing data rates of up to 9.8 Mbps. As a rule, only data rates between 2 and 8 Mbps are used. A motion picture with a duration of approx. 135 minutes can be stored on a DVD-5 in this quality. The standard provides DVD-variants for which video material is coded with a reduced resolution (according to MPEG-2 SP@ML and MPEG-1). These versions are suitable for DVD applications that require storage of a maximum of material. The sound for DVD-Video can be stored in different formats. It is generally possible to store the sound on a DVD as uncompressed PCM SOUND (up to 24 bits/96 kHz) or uncompressed audio format (DOLBY DIGITAL AC-3 or MPEG-1 Layer 2 MP2). A DVD-Video has to offer at least one of these formats. Right after the introduction of DVD, the US and Europe disagreed on the question in which format the sound was to be stored. The NTSC countries soon chose Dolby Digital (AC-3), whereas the PAL countries concentrated on MPEG. Meanwhile both formats are allowed in Europe, and both compression standards are also supported in NTSC countries.
What are Generation losses?
Generation losses are any kind of quality impairment caused by duplicating material. Every recording or re-recording causes a degradation in terms of signal quality. Generation losses are clearly visible in analog magnetic tape recordings.The best quality is limited to the original tape.
Digital systems that use compression may also cause such losses. This digital recording loss is higher, the higher the compression factor. This applies to both digital still pictures and digital video.
What is HDTV?
High Definition Television. General term for all kinds of TV signals offering increased RESOLUTION, i.e. pictures with enhanced sharpness in comparison with most commonly known TV systems. Unfortunately, no worldwide uniform HDTV standard exists. Despite a large bandwidth of different versions with different line numbers and frame frequency, there are some uniformly valid parameters: HDTV works with a 16:9 aspect ratio and a number of lines that is considerably higher than that compared with PAL or NTSC. (1250 lines/50 Hertz and 1125 lines/60 Hertz) is nowadays actively used. HDTV is only used on a small scale worldwide. DTV regulation in the United States will increase the number of HDTV playing modes, among them 1080i (1080 lines, INTERLACED) as well as 720 p (720 lines, PROGRESSIVE).
What is NTSC?
National Television Standards Committee. The NTSC was developed in the USA and is the oldest standard for color picture broadcasting. NTSC operates at 60 Hz and with 525 lines, 60 fields and 30 frames per second. NTSC is used in the USA, Canada and Japan and in many other countries. In Europe, PAL is mainly used for TV broadcasting. The bandwidth of NTSC is 4.2 MHz, the color signal is modulated on an auxiliary signal (subcarrier) at a frequency of 3.58 MHz.
What is PAL?
Phase Alternating Line. PAL is the predominant TV standard in Europe. PAL operates at a frequency of 50 hertz which corresponds to 25 frames or 50 fields and with 625 lines. Compared to NTSC, the type of color transmission is different for PAL which yields advantages for the color stability of the transmitted pictures, but also requires higher technical expenditure and causes problems in post-editing. (FIELD SEQUENCE). In the case of PAL, the bandwidth is 5.5 MHz, the color carrier Sequence 4.43 MHz.
What is a Pixel?
Picture element, picture point. A pixel is the smallest unit within a raster image. Pixels are further divided into square pixels (square picture points) and non square pixels. The reasons for this are as follows: In contrast to computer monitors, video monitors operate with rectangular instead of square pixels, as they are also defined in ITU-R 601 (non square pixel). A PAL picture on a video monitor has 720 x 576 pixels. In the computer field, however, square pixels are the norm. A 4:3 PAL picture must be represented on a computer monitor with 768 x 576 pixels, due to the square pixel form, in order to maintain the same aspect ratios. In the event that the difference between square and non-square pixels is not taken into account by the manufacturer of a computer-based video system, there may be slight distortions in the representation of video images on computer monitors.
What is Resolution?
The better the resolution of a system, format or device, the finer the visible picture details. The resolution is often used as a synonym for sharpness. As a standard, the maximum resolution is indicated in LINES or MEGAHERTZ. The number of lines is predetermined by the individual TV systems and indicates the respective vertical resolution (PAL: 625 lines; 576 of them are active lines that are in fact used for the picture content). For this reason, only the horizontal resolution is indicated. PIXEL NUMBERS are often stated as a measure for resolution, e.g. 720 x 576 which corresponds to the PAL resolution. In common practice one should pay attention to the fact that these indications often refer to system limits and not to values attainable in reality, for they are influenced by individual components ranging from Camcorders to monitors. Each component within the signal path can influence the attained resolution.
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