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Volume 40 (Apr 27, 2005)
A system LSI device that transforms PCs into high-quality image TVs (1/2)
TV function-equipped PCs: The new norm
The diffusion rate for PCs in ordinary households in Japan now exceeds 50%, and the PC is fast becoming an essential home appliance integral to the daily lives of everyone from children to the elderly. PCs have thus evolved to provide functions and designs that better match the needs of consumers in their private lives. Recently, there has been an increase in the number of home-use PC models that come equipped with AV functions, thereby making it possible to not only enjoy music and video footage via CD and DVD drives, but also watch television programs. Most TV function-equipped PCs can also be used as a DVD recorder, now a commonly used digital AV appliance.
Once viewing TV programs via PCs became possible, consumers naturally began to desire PCs capable of providing the clearest possible high-quality images. It can be concluded that needs like these were inevitable considering that ordinary television screens have become increasingly larger in size in recent years and now provide images of much higher quality. Along with the development of displays capable of producing pictures that are more vivid than ever before, a new LSI chip for PC use that integrates a wide variety of image-quality functions on a single chip is now attracting a great deal of attention.
All of the PC models with TV tuners introduced by NEC this year come equipped with a newly developed TV board, and the µPD61153 image processing LSI chip from NEC Electronics Corporation is the heart of this TV board.
Image processing LSI functions used to achieve high quality
The µPD61153 condenses each of the following essential functions for a TV tuner board on a single chip: (1) 10-bit A/D converter that digitizes analog images and thereby makes it possible to view TV programs via a PC; (2) three-dimensional(3D) luminance/chrominance (Y/C) separator function; (3) video decoder function; (4) time- base corrector; (5) MPEG2 encoder function; (6) PCI interface supporting 4-channel simultaneous PCI master transmissions (Figure 1). By integrating all of these functions on a single chip rather than allocating each function to an individual chip as was done in the past, it is possible to control noise that is generated from the connections between chips as well as improve image quality. Moreover, by connecting the 陲鳳D64031A, a ghost reducer LSI chip, and a digital direct, the conversion process for analog and digital signals from TV images only needs to be executed once. This, in turn, enables the realization of high-quality image processing with minimal degradation in image quality.
Another important issue that must be considered when developing home-use PCs is cost. Integrating the aforementioned functions onto one chip leads to a dramatic decrease in cost, which helps manufacturers meet the demands of consumers who want PCs equipped with high-quality TV functions at even cheaper prices.
Let's take a closer look at each of the high-quality functions. (1) With the 10-bit A/D converter, analog video signals received by the TV tuner are converted to digital signals with 10-bit high resolution so that images can be clearly and naturally reproduced down to the finest of details. (2) Image noise can be controlled using the 3D Y/C separator function (a function large-screen TVs are standardly equipped with) to separate the luminance and chrominance signals contained in video signals. This function enables the realization of a clear picture with little color blur. (3) The video decoder function makes it possible to convert TV signals to data that can be handled by PCs and MPEG2 encoders. It is at this time that fine adjustments are made to images (for example, luminance, color and sharpness). (4) Use of the time-base corrector reduces screen flickering and distortion. (5) The MPEG2 encoder function is used to compress/convert digital video data and sound data into MPEG2 data, which is used with DVD recorders, etc. (6) The PCI interface supporting 4-channel simultaneous PCI master transmission makes it possible for video blanking information (for example, data encoded by MPEG2, digital video and sound data that has not been compressed, or subtitle data that is mixed with incoming analog dynamic image signals) to be simultaneously transferred to a user's PC. This, in turn, enables high-speed data exchange between the user's TV and PC, thus allowing the user to easily carry out operations such as the recording and editing of programs.
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