Patent ID: 8731311
Filing Date: 2014-05-20
Classification: H04N

Abstract:
1. A decoding device for decoding an encoded sequence generated by predictive encoding a plurality of frame images, wherein the encoded sequence is composed of a plurality of encoded frame images, each of the encoded frame images includes a plurality of encoded pixel blocks, at least part of the encoded plurality of pixel blocks is generated by predictive encoding a pixel block that refers to a reference pixel block and includes reference relationships information that indicates that the pixel block refers to the reference pixel block, and the reference relationships information includes reference frame information and reference position information which respectively indicate a reference-destination frame image and a reference position in a reference-destination reference pixel block, the decoding device comprising: a main memory storing a plurality of decoded frame images; and a processor having a cache memory whose capacity is at least a data size of the reference pixel block and is less than a data size of the frame image, the processor, by executing an application program, operating as: an obtaining unit operable to obtain the encoded sequence; an extracting unit operable to extract a plurality of pieces of reference relationships information from the obtained encoded sequence; an identifying unit operable to select one frame image among a plurality of reference-destination frame images that are indicated by a plurality of pieces of reference frame information included in the extracted plurality of pieces of reference relationships information, extract a plurality of pieces of reference position information respectively from all of a plurality of pieces of reference relationships information including a plurality of pieces of reference frame information that indicate the selected frame image as the reference-destination frame image, generate a reference list that is composed of the extracted plurality of pieces of reference position information, and identify, from the generated reference list, all reference-source encoded pixel blocks that refer to a same reference pixel block, for each of a plurality of reference pixel blocks included in the selected frame image; a storing unit operable to read out one reference pixel block included in the reference-destination frame image from the main memory, and store the read-out reference pixel block into the cache memory; and a decoding unit operable to determine, using the reference list, all encoded pixel blocks that refer to the reference pixel block while the reference pixel block itself is stored in the cache memory without being discarded, and decode all the determined encoded pixel blocks, wherein the identifying unit, when identifying all the reference-source encoded pixel blocks, calculates Macro Block Address (MBA) values based on reference positions respectively indicated by all the plurality of pieces of reference position information included in the generated reference list, and identifies all pieces of reference position information from which the same MBA value is calculated, the MBA values indicating positions of reference pixel blocks to be referred to, and further re-arranges the plurality of pieces of reference position information included in the reference list so that all the pieces of reference position information from which the same MBA value is calculated continuously appear in the reference list, and the decoding unit decodes all the determined encoded pixel blocks in an order of the pieces of reference position information arranged in the reference list after the re-arrangement thereof.