| 摘要 |
Apparatus and methods are provided for encoding independently decodable pieces of compressed data to accommodate reordering of the pieces of compressed data before or after manipulation. Encoding can occur before or after manipulation of the source information. For example, in the context of a JPEG image, MCUs can be rotated and promptly compressed with restart markers without extra buffering to put the MCUs in the correct rotated order. Later, the order of the independently decodable pieces can be changed to accommodate proper output. Alternatively, pointers to the independently decodable pieces can be used to present the data to the decoder in the proper order. Additional reentry information within the independently decodable pieces of compressed data can allow initiation of decoding at other than the independently decodable points. Such reentry information preferably would include bit-level pointers and sufficient state information to initialize the decoder properly. For example, in the context of a JPEG image, in addition to the typical information available to the decoder that has been passed in earlier markers, the reentry information for a given MCU boundary may include: a bit-level pointer to the first block's DC Huffman code, the position of the output, and a DC predictor for each component of the MCU.
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