| 摘要 |
PURPOSE: A JPEG data stream controller for processing motion pictures is provided to make an irregular data stream uniform through instantaneous adjustment of compression ratio. CONSTITUTION: A JPEG data stream controller for processing motion pictures includes a pixel bus interface(10) for receiving pixels, a DCT/IDCT unit(20) for receiving the output signal of the interface to perform DCT, a quantizer(30), and a quantization index(35) for selecting a quantization table used for quantization. The controller further includes N quantization tables(40) selected by the quantization index, a zero-pack unit(50) for carrying out run-length encoding, a Huffman coding unit(60) for performing Huffman coding, and a Huffman index(65) for selecting a Huffman table required for the Huffman coding unit. The controller also has N Huffman tables(70) selected by the Huffman index, a host bus interface(80) for connecting compression data to a host, a counter(85) for counting the quantity of compression data, and a comparator(90) for comparing the counted value with a reference data to output a control signal to the quantization index and Huffman index.
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