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Compression Networks

{{Short description|Digital content delivery system}}

{{Unreferenced|date=December 2009}}

'''Compression Networks''' is a [[Digital data|digital]] content delivery system developed by [[TV/COM International]] that evolved into the current [[DVB-S]] standard for [[satellite broadcasting]]. The system provided [[MPEG2]] video, audio, signalling, enhanced program guide, and [[conditional access]] for pay-television services like [[AlphaStar (satellite broadcasting service)|AlphaStar]].

==See also==

* [[EchoStar]]

[[Category:Satellite television]]

[[Category:Broadcasting]]

[[Category:Video]]

{{Tv-tech-stub}}

Category:Video formats

{{Cat main|video format}}

[[Category:Film and video technology]]

[[Category:Media formats|Video]]

[[Category:Video]]

Category:Video on demand

Aritlces related to [[video on demand]] technology.

[[Category:Film and video technology]]

[[Category:Internet broadcasting]]

[[Category:Streaming television]]

[[Category:Network service]]

[[Category:New media]]

[[Category:Online services]]

[[Category:Streaming]]

[[Category:Video]]

Video interlude

A '''video interlude''' is an [[Entr'acte|interlude]] during a performance that shows a [[video]]. Video interludes are often played in [[concerts]], showing a [[music video]] (often made specifically for the show), usually featuring the [[artists]] while the artist takes a break or costume change.

Video interludes have been used by [[Madonna (entertainer)|Madonna]] since at least 1990.<ref>{{Cite web |title=Come Alive |url=https://todayinmadonnahistory.com/tag/come-alive/ |access-date=2022-10-14 |website=Today In Madonna History |language=en}}</ref>

== References ==

<references />

[[Category:Video]]

{{music-video-stub}}

Category:Video compression

{{Commons category|Video compression}}

This category dedicated to [[video compression]] issues (mainly video codec parts).

{{See also|category:video codecs|video file format|audio file format|Digital container format{{!}}container format}}

[[Category:Video]]

[[Category:Data compression]]

[[Category:Video processing]]

[[Category:Applications of artificial intelligence]]

Scan conversion

{{Short description|Video processing technique}}{{For|conversion of vector images to raster images|Rasterisation}}

{{multiple issues|

{{more footnotes|date=August 2013}}

{{refimprove|date=August 2013}}

}}

'''Scan conversion''' or '''scan converting rate''' is a [[video processing]] technique for changing the vertical / horizontal scan frequency of video signal for different purposes and applications. The device which performs this conversion is called a '''scan converter'''.<ref name="patent CA1103345A1"/>

The application of scan conversion is wide and covers video projectors, cinema equipment, TV and [[video capture]] cards, standard and HDTV [[television]]s, LCD monitors, radar displays and many different aspects of picture processing.

== Mechanisms and methods ==

Scan conversion involves changing the picture information data rate and wrapping the new picture in appropriate [[synchronization]] signals.

There are two distinct methods for changing a picture's data rate:

;Analog Methods (Non retentive, memory-less or real time method)

This conversion is done using large numbers of delay cells and is appropriate for analog video. It may also be performed using a specialized scan converter vacuum tube.<ref name="patent CA1103345A1"/> In this case [[polar coordinates]] (angle and distance) data from a source such as a radar receiver, so that it can be displayed on a [[raster scan]] (TV type) display.

;Digital methods (Retentive or buffered method)

In this method, a picture is stored in a line or frame buffer with n1 speed (data rate) and is read with n2 speed, several picture processing techniques are applicable when the picture is stored in buffer memory including kinds of interpolation from simple to smart high order comparisons, motion detection and … to improve the picture quality and prevent the conversion artifacts.<ref name="patent CA1103345A1">[http://www.google.com/patents/US4220969 US patent US4220969 / CA1103345A1], Kazuhiko Nitadori, "Digital scan converter", published September 2, 1980. assigned to OKI Electric Ind. C. Ltd. Retrieved August 19, 2013</ref>

== How to realize ==

The process in practice is applicable only using integrated circuits in [[Large Scale Integration|LSI]] and [[VLSI]] scales. Timing, interference between digital and analog signals, clocks, noise and exact synchronization have important roles in the circuit.

Digital conversion method needs the analog video signal to be converted to digital data at the first step.

A scan converter can be made in its basic structure using some high speed integrated circuits as a circuit board however there are some integrated circuits which perform this function plus other picture processing functions like scissoring, change of [[aspect ratio (image)|aspect ratio]] and … an easy to use example was SDA9401

== Some examples ==

[[File:Scan converter SW-22050 big.jpg|thumb|A VGA to TV scan converter box like this turns enhanced-definition or high-definition signals into standard-definition signals.]]

Up conversion ([[interpolation]]):

* In many [[LCD]] monitors there is a native picture mode, however the monitor can display different graphical modes using a scan converter.

* In a [[100 Hz]]/120&nbsp;Hz analog TV, there is a scan converter circuit which converts the vertical frequency (refresh rate) from standard 50/60&nbsp;Hz to 100/120&nbsp;Hz to achieve a low level of flicker which is important in large screen (high inch) TVs.

* An external TV card receives the TV signals and converts them to VGA or [[SVGA]] format to display on monitor.

Down conversion ([[Decimation (signal processing)|decimation]]):

* Many [[graphic cards]] have output for [[standard-definition television]]. Here there is a conversion from computer graphical modes to TV standard formats.

* Other graphic cards lack an SDTV output, but their VGA outputs can still be connected to an SDTV through an external scan converter (pictured).