Sony Corporation

Yu Liu

Naofumi Yanagihara

Kazushi Sato

Shintaro Okada

Takeshi Kubozono

Kazushi Satoh

A picture information conversion method and apparatus in which, if the compressed picture information with a variable or non-recognized information volume is input, optimum compression processing on the compressed picture information is performed to prevent underflow and/or overflow to suppress deterioration of the picture quality. A compressed information analysis device analyzes the structure of the picture type of the GOP of the compressed picture information input to the FF buffer . A bit allocation device generates a pseudo GOP of the input compressed picture information, based on N frames stored in the FF buffer and on the analysis result information stored in the information buffer , and allocates a pre-set code volume to respective pictures of the generated GOP so that the output compressed picture information will be at a second bitrate.

Picture information conversion method and apparatus

An apparatus and a method for transforming picture information can significantly reduce the bit rate. A picture information transform apparatus for receiving as input the compressed picture information obtained by coding the picture information of a plurality of picture type images by ways of orthogonal transform and motion compensation includes a variable length decoder for performing a variable length decoding operation on the input compressed picture information, an inverse quantizer for inversely quantizing the decoded information, a band limiter for limiting the bandwidth, a quantizer and a bit rate controller for computationally determining the target bits for the coded images of each picture type by adaptively using a plurality of parameters operating as coefficients for the contents of the coded images of the picture type on the bais of the contents of the coded images of the picture type.

Apparatus and method for transforming picture information

A technique is disclosed for reducing the bit rate of a bit stream coded into a compressed form according to the MPEG-2 standard, without causing significant degradation in image quality of a decoded image. An inverse DCT converter dequantizes a MPEG-2 bit stream and outputs resultant discrete cosine transform coefficients for each DCT block. A band limiter replaces the values of high-frequency components of the discrete cosine transform coefficients in the horizontal direction, with 0. A quantizer quantizes the discrete cosine transform coefficients using a quantization step value different from the original value.

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Tokyo, Japan

Yu Liu