IMAGE DATA COMPRESSOR AND ENCODER

摘要

PROBLEM TO BE SOLVED: To provide an image data compressor for surely generating compressed data at a constant rate by carrying out the prevention of deterioration in display quality and by optimizing the sharing between hardware and software and to provide an encoder.

SOLUTION: The image data compressor 10 includes: a quantization section 20; an FIFO buffer section 30; an encoded data generating section 40; and a rate control section 50. The quantization section 20 quantizes the image data in a quantization step wherein the image data are changed on the basis of a quantization parameter. The FIFO buffer section 30 stores quantized data quantized by the quantization section 20 by at least N (N is an integer of 2 or over) frames. The encoded data generating section 40 encodes the quantization data read asynchronously with the writing to the FIFO buffer section 30 to generate encoded data. The rate control section 50 uses an average data size of the encoded data by past N frames to obtain the quantization parameter. The quantization parameter is obtained so that its value is a quantization parameter upper limit threshold value or below set or released on the basis of the number of assignable bits assignable to the compression processing and the number of remaining frames.

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