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Aptiva - MPEG Information
Applicable to: United States
Q. What is MPEG?
A. MPEG is a standard for video and audio compression that allows personal computers to display television-quality images and sound. MPEG stands for Moving Pictures Experts Group, which is a part of the International Standards Organization (ISO).
Q. Why does anyone need to compress video and audio?
A. Without compression, the image that your television displays would require roughly 100 million bits of information per second (Mbps) to store digitally. At this rate, even the most powerful personal computers would be overwhelmed by only a few minutes of video. Additionally, the preferred medium for video and audio is the CD-ROM, which typically transfers data at rates ranging from 1.4-5.6 Mbps. The speed of a CD-ROM is nowhere near fast enough to handle a video signal. Audio is also quite demanding on the system, requiring 1.4 Mbps to transfer CD-quality stereo sound. While a CD-ROM has no trouble handling this, it would leave little room for anything else, including video
Q. What is the difference between MPEG-1 and MPEG-2?
A. MPEG-1 and MPEG-2 are two different specifications for compressing video. MPEG-1 was the original MPEG standard, and was designed to work well with low-speed devices such as CD-ROM's. MPEG-2 is a higher performance specification that is designed to allow broadcast-quality images using higher speed storage devices.
Q. How does MPEG video compression work?
A. MPEG takes advantage of a few simple concepts to minimize the amount of information necessary for video. First, MPEG divides the image into two channels, one for luminance (brightness), and one for chrominance (color information). Because the human eye is less sensitive to color than to brightness, MPEG drops a great deal of information in the chrominance channel without much loss in picture quality. MPEG then further divides each channel into a grid of separate blocks. MPEG uses mathematical techniques to compress the blocks so that they require less information to display. MPEG also allows for motion compensation, which means that the computer predicts changes in the picture over time.
Q. How does MPEG audio compression work?
A. MPEG uses a sophisticated technique called psychoacoustic modeling to reduce the data requirements of sound. Simply put, the human ear has trouble perceiving all of the sound it hears. Irrelevant and redundant parts of the sound signal are simply removed, reducing the data requirements. While this technique is simple in concept, it requires very sophisticated signal processing to work properly.
Q. Which IBM products support MPEG?
A. The IBM PC Company offers two products that support MPEG. First, the new IBM Aptiva series of personal computers include Total Image Video and TheatreSound. These products take advantage of the Aptiva's Media Processor to decode MPEG-1 audio, freeing the Pentium processor to decode MPEG-1 video. The result is full-screen, full-motion video with crisp stereo audio.
Secondly, the IBM Thinkpad 760 also includes Total Image Video, but in a slightly different implementation. The Thinkpad 760 includes the IBM MPEG-2 Decoder chip to decode MPEG-1 and MPEG-2 data extremely high performance and quality.
Q. How do I use MPEG?
A. The new Aptivas and the Thinkpad 760 come with a selection of multimedia entertainment packages that take advantage of Total Image Video. In addition, both products include a Microsoft Windows driver to allow other multimedia programs to access the computer's MPEG capabilities.
Q. Will MPEG work with all my multimedia software?
A. MPEG is just one of many different ways of encoding video and audio for use in multimedia PC's. Others include Microsoft's Video for Windows and Apple's QuickTime. Unless your software uses MPEG-coded data, it will not take advantage of your computer's MPEG capabilities. Some software titles ship in MPEG versions, and more should follow as the MPEG standard gains acceptance.
Q. Is MPEG video as sharp and clear as my television?
A. MPEG-1 is generally used to encode a video signal that compares to a VHS tape in quality. Keep in mind, however, that it is up to the software developer to make sure the video is encoded with high quality. Another thing to remember is that a computer monitor can display much more information than a television can. The amount of information that a typical MPEG-1 video stream produces takes up about one-fourth of a VGA display. To fill the VGA display with picture, the hardware must actually do much more work. Currently, the 100MHz Pentium processor is capable of handling this task, but not quite with the same clarity of a VCR.
On the Thinkpad 760, MPEG-2 is decoded with the use of a specialized decoder chip that can better handle the demands of video decompression. This product will provide quality that is equivalent to that of a good VCR, even on a full-screen VGA display.
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Hint Category |
Video, General Information | |
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Date Created |
15-04-97 | |
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Last Updated |
22-04-98 | |
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Revision Date |
20-04-99 | |
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Brand |
IBM Aptiva | |
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Product Family |
Aptiva | |
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Machine Type |
2144, 2159, 2161, 2162, 2176 | |
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Model |
C8E; C8H; C8X; C9E; C9S; C9X; 21R; 22R; 24R; 25R; 6R6; C21; C31; C32; 6R9; C31; F31; C6D; 8R6; 8R9; 9R4; 6R8; 7R1; 7R3; 7R6; 7R7; 7R9; 7RO; 8R1; 8R8; 9R2; 9R3; C23; C33; C35; C55; C56; C65; C66; C67; C6V; C6Y; C6Z; C73; C76; C77; F23; F33; F35; F67; 5R5; M91; 2R5; 2R7; 2R8; M30; M35; M50; 2R6; 4R7; 4R8; M40; M54; M58; 3R0; 3R8; M60; M70; 3R4; 3R6; 4R1; 4R9; M31; M51; M52; M63; 2R9; 3R1; 3R3; 3R5; 3R7; 3R9; 4R0; 4R2; 4R3; M41; M53; M55; M56; M57; M61; M62; M71; M72; 5R1; 6R3; A10; A12; A14; 5R2; 5R3; 5R6; 5R8; 5R9; 6R0; 6R4; 6R5; A15; A40; A44; A45; A50; A51; A52; A90; A92; A94; S64; S66; S74; S7H; S78; 13R; 14R; 15R; 16R; 19R; 20R; S8C; S8H; S9H; S9C; 28R; 29R; 31R; S80; S90; 17R; 18R | |
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2144c8e | |
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