Mediaprocessor
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A Mediaprocessor is a microprocessor-based System-on-a-chip which is designed to deal with digital streaming data at real-time (e.g. display refresh) rates. These devices can also be considered a class of digital signal processors.
Unlike similar Graphics processing units, which are used for computer displays, mediaprocessors are targeted at digital televisions and set-top boxes.
The streaming digital media classes include:
- uncompressed digital video
- compressed digital video - e.g. MPEG-1, MPEG-2, MPEG-4
- digital audio- e.g. PCM, AAC
Such SOCs are composed of:
- a microprocessor optimized to deal with these media datatypes
- a memory interface
- streaming media interfaces
- specialized functional units to help deal with the various digital media codecs
The microprocessor might have these optimizations:
- vector processing or SIMD functional units to efficiently deal with these media datatypes
- DSP-like features
Previous to mediaprocessors, these streaming media datatypes were processed using fixed-function, hardwired ASICs, which could not be updated in the field. This was a big disadvantage when any of the media standards were changed. Since mediaprocessors are software programmed devices, the processing done on them could be updated with new software releases. This allowed new generations of systems to be created without hardware redesign. For set-top boxes this even allows for the possibility of in-the-field upgrade by downloading of new software through cable or satellite networks.
Companies that pioneered the idea of mediaprocessors (and created the marketing term of mediaprocessor) included:
- Microunity Mediaprocessor - device never reached production
- Equator Semiconductor BSP line - their processors are used in Hitachi televisions, company acquired by Pixelworks
- Chromatic Research MPact line - their products were used on some PC graphics cards in the mid 1990s, company acquired by ATI Technologies
- Philips Trimedia line - used in Philips, Dell, Sony, etc. consumer electronics, Philips Semiconductors split of from Philips and became NXP in 2006
Consumer electronics companies have successfully dominated this market by designing their own mediaprocessors and integrating them into their video products. Companies such as Philips, Samsung, Matsushita, Fujitsu, Mitsubishi have their own in-house mediaprocessor devices.
Newer generations of such devices now use various forms of multiprocessing - multiple CPUs, DSPs, ALUs in order to deal with the vastly increased computational needs when dealing with high definition television signals.
