Information about Qpel
Quarter pixel (also known as Q-pel or Qpel) refers to a quarter of a standard pixel. It is used in many modern video encoding standards such as MPEG-4 ASP and H.264/AVC to refer to a motion estimation precision of a quarter pixel.
Operation
Video encoding methods such as those based upon MPEG-4 specifications, for example XviD, 3ivx, and DivX, use motion estimation algorithms to significantly improve video compression. The default level of resolution for motion estimation for most MPEG-4 implementations is half a pixel, although quarter pixel is specified under the standard. H.264/MPEG-4_AVC specifies quarter pixel as default. Since the quality increase gained by the use of Qpel is not always enough to offset the increased bit cost of a quarter-pixel precision motion vector, rate-distortion optimization significantly improves the effectiveness of quarter-pixel precision motion estimation.Hardware compatibility (MPEG-4 ASP)
Qpel requires up to twice as much processing power to encode, and 30-60% more processing power to decode. For this reason, and to enable wider hardware compatibility, Qpel is disabled in the default DivX encoding profiles. pixel (short for picture element, using the common abbreviation "pix" for "pictures") is a single point in a graphic image. Each such information element is not really a dot, nor a square, but an abstract sample.
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MPEG-4 Part 2 is a video compression technology developed by MPEG. It belongs to the MPEG-4 ISO/IEC standard (ISO/IEC 14496-2). It is a Discrete Cosine Transform compression standard, similar to previous standards such as MPEG-1 and MPEG-2.
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Motion perception is the process of inferring the speed and direction of objects and surfaces that move in a visual scene given some visual input. Although this process appears straightforward to most observers, it has proven to be a difficult problem from a computational
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MPEG-4 is a standard used primarily to compress audio and visual (AV) digital data. Introduced in late 1998, it is the designation for a group of audio and video coding standards and related technology agreed upon by the ISO/IEC Moving Picture Experts Group (MPEG) under the formal
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Xvid (formerly "XviD") is a video codec library following the MPEG-4 standard. Xvid features MPEG-4 Advanced Simple Profile features such as b-frames, global and quarter pixel motion compensation, lumi masking, trellis quantization, and H.
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3ivx is a video codec created by 3ivx Technologies, based in Sydney, Australia.
3ivx (pronounced "Thriv-ex") is a codec suite that allows the creation of MPEG-4 compliant data streams.
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3ivx (pronounced "Thriv-ex") is a codec suite that allows the creation of MPEG-4 compliant data streams.
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DivX are a brand name of products created by DivX, Inc. (formerly DivXNetworks, Inc.), including the DivX Codec which has become popular due to its ability to compress lengthy video segments into small sizes while maintaining relatively high visual quality.
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Motion perception is the process of inferring the speed and direction of objects and surfaces that move in a visual scene given some visual input. Although this process appears straightforward to most observers, it has proven to be a difficult problem from a computational
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Video compression refers to reducing the quantity of data used to represent video images, and this is almost always coupled with the goal of retaining as much of the original's quality as possible.
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MPEG-4 is a standard used primarily to compress audio and visual (AV) digital data. Introduced in late 1998, it is the designation for a group of audio and video coding standards and related technology agreed upon by the ISO/IEC Moving Picture Experts Group (MPEG) under the formal
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Rate-distortion optimization (also RDO or RD) is a method of improving video quality in video compression. The name refers to the optimization of the amount of distortion
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