Patent ID: 9078003
Filing Date: 2015-07-07
Classification: H04N

Abstract:
1. A picture coding and decoding system which includes a picture coding apparatus for coding a picture in a moving image and a picture decoding apparatus for decoding a picture in a moving image from a bit stream, wherein said picture coding apparatus comprises: a first and second information generating unit operable to generate, on a picture-by-picture basis, either of (i) first information indicating that a target picture, which is one of an I picture, a P picture, and B picture, can be a reference picture to be referred to when coding at least one of P pictures following the target picture or coding at least one of B pictures following the target picture and (ii) second information indicating that the target picture cannot be a reference picture to be referred to when coding each of P pictures following the target picture or coding each of B pictures following the target picture; a third information generating unit operable to generate, on a picture-by-picture basis, (iii) third information indicating a plurality of candidate reference pictures, each of the candidate reference pictures being a candidate for a reference picture selected from among pictures for which only the first information is attached, when coding a target P picture or coding a target B picture; a fourth information generating unit operable to generate, on a block-by-block basis, (iv) fourth information indicating one specified reference picture to be referred to when performing predictive coding on a target block included in the target P picture or indicating one or two specified reference pictures to be referred to when performing predictive coding on a target block included in the target B picture; a first storing unit operable to store, on a picture-by-picture basis, the target picture into a memory as a candidate reference picture only when the first information is generated for the target picture by the first and second information generating unit; a coding unit operable to code, on a block-by-block basis, the target block by using the one specified reference picture when performing predictive coding on the target block included in the target P picture or by using the one or two specified reference pictures to be referred to when performing predictive coding on the target block included in the target B picture to generate coded block data; and a bit stream generating unit operable to generate a bit stream corresponding to the moving image, by adding the first information, the second information, the third information and the fourth information to the coded block data, wherein said one specified reference picture is specified on a block-by-block basis, from among a plurality of candidate reference pictures which are stored in the memory, and the target block is predictively coded with reference to the one specified reference picture when performing predictive coding on the target block included in the target P picture, and wherein said one or two specified reference pictures are specified, on a block-by-block basis, from among a plurality of candidate reference pictures which are stored in the memory, and the target block is predictively coded with reference to the one or two specified reference pictures when performing predictive coding on the target block included in the target B picture, and wherein said picture decoding apparatus comprises: a first and second information extracting unit operable to extract, from the bit stream on a picture-by-picture basis, either of (i) first information indicating that a target picture, which is one of an I picture, a P picture, and B picture, can be a reference picture to be referred to when decoding at least one of P pictures following the target picture or decoding at least one of B pictures following the target picture and (ii) second information indicating that the target picture cannot be a reference picture to be referred to when decoding each of P pictures following the target picture or decoding each of B pictures following the target picture; a third information extracting unit operable to extract from the bit stream on a picture-by-picture basis, (iii) third information indicating a plurality of candidate reference pictures, each of the candidate reference pictures being a candidate for a reference picture selected from among pictures for which only the first information is attached, when decoding a target P picture or decoding a target B picture; a fourth information extracting unit operable to extract from the bit stream on a block-by-block basis, (iv) fourth information indicating one specified reference picture to be referred to when performing predictive decoding on a target block included in the target P picture or indicating one or two specified reference pictures to be referred to when performing predictive decoding on a target block included in the target B picture; a second storing unit operable to store, on a picture-by-picture basis, the target picture into a memory as a candidate reference picture only when the first information is extracted by the first and second information extracting unit; and a decoding unit operable to decode, on a block-by-block basis, the target block by using the one specified reference picture when performing predictive decoding on the target block included in the target P picture or by using the one or two specified reference pictures to be referred to when performing predictive decoding on the target block included in the target B picture, wherein said one specified reference picture is specified on a block-by-block basis, from among a plurality of candidate reference pictures which are stored in the memory, and the target block is predictively decoded with reference to the one specified reference picture when performing predictive decoding on the target block included in the target P picture, and wherein said one or two specified reference pictures are specified, on a block-by-block basis, from among a plurality of candidate reference pictures which are stored in the memory, and the target block is predictively decoded with reference to the one or two specified reference pictures when performing predictive decoding on the target block included in the target B picture.