摘要:
An MPEG-II audio decoder with a synthesis subband filter includes a fast IMDCT (Inverse Modified Discrete Cosine Transform) module and an IPQMF (Inverse Pseudo Quadrature Mirror Filter) module. The fast IMDCT module involves a butterfly stage of input subband samples which requires only about ¼ the amount of multiplier-accumulate computation of the ISO suggested method. The IPQMF module involves an efficient memory configuration which requires only half size of the standard synthesis subband filter bank.
摘要:
A hardware structure for inverse quantization and multichannel processing in MPEG-2 audio decoding is provided, which includes 5 groups of first-in-first-out (abbreviated as FIFO) registers, each group of which has 3 FIFO registers and are connected in series; a multiplier capable for receiving an internal data processing feedback from the last FIFO group of FIFO registers; a single register; a first adder/subtractor capable for receiving a feedback from the first group of FIFO registers and its output being fed to the first group of FIFO registers; a second adder/subtractor capable for receiving a feedback from a second group of FIFO registers. The second group of FIFO registers stores an output from the second adder/subtractor or an output from the first group of FIFO registers; a third group of FIFO registers stores an output from the single register or an output from the second group of FIFO registers; a fourth group of FIFO registers stores an output from the third group of FIFO registers; and so on. The single register output the calculated value of the multiplier as an output of the structure or to at least one of the first second adder/subtractor, second adder/subtractor and the third group of FIFO registers.
摘要:
The invention describes a simple and efficient codeword degrouping algorithm which can be applied in an MPEG audio decoder, in which a codeword is degrouped into three samples. According to the proposed algorithm, the division and modulo computations applied in the original degrouping method can be fully substituted into the addition and subtraction computations by using the mode selection and iterative decompositions, and thus largely reduces the overhead and complexity for the decoder. Also, an efficient architecture for the proposed algorithm includes one special adder, two subtractors, and two adders. The architecture generates the quotient and remainder simultaneously with fix-rate throughput.
摘要:
This invention provides an image capturing lens system comprising three non-cemented lens elements with refractive power: a first lens element with positive refractive power having a convex object-side surface, and both the object-side and image-side surfaces being aspheric; a plastic second lens element with negative refractive power having a concave object-side surface and a convex image-side surface, and both the object-side and image-side surfaces being aspheric; and a plastic third lens element having a convex object-side surface and a concave image-side surface, and both the object-side and image-side surfaces being aspheric. By such arrangement, the space of the image capturing lens system can be allocated much more properly and thereby an image capturing lens system with shorter total track length can be obtained while retaining superior image quality.
摘要:
An image lens system includes, in order from an object side to an image side, a first lens element with negative refractive power including a concave image-side surface; a second lens element with positive refractive power including a convex object-side surface; a third lens element with negative refractive power including an object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric; a fourth lens element with positive refractive power including a convex object-side surface and a convex image-side surface; and a fifth lens element with negative refractive power including a convex object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric, the fifth lens element having at least one inflection point.
摘要:
An image capturing system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element has positive refractive power. The fourth lens element with negative refractive power has a concave object-side surface and a convex image-side surface, wherein at least one of the object-side surface and the image-side surface of the fourth lens element is aspheric. The fifth lens element with refractive power has a concave image-side surface, wherein at least one of an object-side surface and the image-side surface of the fifth lens element is aspheric, and the fifth lens element has at least one inflection point on the image-side surface thereof.
摘要:
An optical imaging system includes, in order from an object side to an image side, a first lens element with a positive refractive power, a second lens element, a third lens element, a fourth lens element with a positive refractive power having an aspheric surface and a fifth lens element with a negative refractive power. An image-side surface of the fifth lens element is concave, and at least one of two surfaces of the fifth lens element is aspheric. The relationship between a sum of thicknesses of all lens elements with refractive powers on an optical axis and a distance on the optical axis between an object-side surface of the first lens element and the image-side surface of the fifth lens element in the optical imaging system can effectively reduce the total length as well as the sensitivity of the optical imaging system while gaining superior resolution.
摘要:
An image lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element with refractive power is made of plastic material, and has at least one surface being aspheric. The fourth lens element with refractive power is made of plastic material, and has a concave object-side surface and a convex image-side surface, wherein at least one surface of the fourth lens element is aspheric. The fifth lens element with positive refractive power is made of plastic material, and has a convex object-side surface and a convex image-side surface, wherein at least one surface of the fifth lens element is aspheric.
摘要:
This invention provides an imaging lens system in order from an object side to an image side comprising: a first lens element with positive refractive power; a plastic second lens element with negative refractive power having a concave object-side surface and a convex image-side surface, both surfaces thereof being aspheric; and a plastic third lens element with negative refractive power having a convex object-side surface and a concave image-side surface, both surfaces thereof being aspheric, and at least one inflection point is formed on at least one of the object-side and image-side surfaces thereof. Additionally, the central thickness of the second lens element is controlled favorably for the efficient spatial arrangement of the lens assembly and the simpler individual lens production while maintaining suitable thickness of the second lens element, thereby assuring image quality and improving yield rate of the product.