Circuitry of a decoder is configured to decode an image according to a coding structure including an intra random access point (IRAP) picture, leading pictures to be output before the IRAP picture in output order, and trailing pictures to be output after the IRAP picture in the output order. When the image is decoded, the circuitry decodes, according to a flag in a bitstream, at most one trailing picture among the trailing pictures before decoding the leading pictures in decoding order, and decodes the trailing pictures other than the at most one trailing picture after decoding the leading pictures in the decoding order. The flag indicates whether a picture of each of access units in the bitstream is a field picture. The circuitry decodes the at most one trailing picture before decoding the leading pictures in the decoding order when the flag indicates that the picture is a field picture.

The present invention relates to an encoding apparatus and an encoding method capable of reducing the overhead on a macroblock basis. A number of reference image decision unit 19 determines that the number of fields of the reference image in encoding is one on the basis of the bit rate of the coded data. If the number of fields of the reference image is determined to be one, a slice header generating unit 13 selects, from among pictures input to an image sorting buffer 12, one of the pictures as the reference image. The present invention is applicable to, for example, encoding apparatuses that perform video coding based on the AVC standard.

The present invention relates to an encoding apparatus and an encoding method capable of reducing the overhead on a macroblock basis. A number of reference image decision unit 19 determines that the number of fields of the reference image in encoding is one on the basis of the bit rate of the coded data. If the number of fields of the reference image is determined to be one, a slice header generating unit 13 selects, from among pictures input to an image sorting buffer 12, one of the pictures as the reference image. The present invention is applicable to, for example, encoding apparatuses that perform video coding based on the AVC standard.

An encoding method includes determining video format information, (i) setting each of all frames or all fields which are included in the video, as a picture, regardless of whether the video format is the interlace format or the progressive format, (ii) setting a POC indicating display order to each of all of the set pictures one by one, the POC being different each other, and encoding a picture to be encoded which is the frame or the field with reference to a picture previously encoded before encoding the picture to be encoded. In the encoding, the video is encoded with a syntax structure which is not dependent on the video format, the video format information is encoded in a header of a sequence which is a unit of the video, and the encoded bit stream is generated.

A moving picture encoding apparatus encodes a moving picture having an interlaced structure, and includes: a storage which stores fields as reference pictures; and an encoder which encodes a current field as a B-picture, using a first reference picture list which includes only one field in a same parity as the current field, and a second reference picture list which includes only one field in an opposite parity to the current field.

Video decoding innovations for multithreading implementations and graphics processor unit (“GPU”) implementations are described. For example, for multithreaded decoding, a decoder uses innovations in the areas of layered data structures, picture extent discovery, a picture command queue, and/or task scheduling for multithreading. Or, for a GPU implementation, a decoder uses innovations in the areas of inverse transforms, inverse quantization, fractional interpolation, intra prediction using waves, loop filtering using waves, memory usage and/or performance-adaptive loop filtering. Innovations are also described in the areas of error handling and recovery, determination of neighbor availability for operations such as context modeling and intra prediction, CABAC decoding, computation of collocated information for direct mode macroblocks in B slices, reduction of memory consumption, implementation of trick play modes, and picture dropping for quality adjustment.

Video decoding innovations for multithreading implementations and graphics processor unit (“GPU”) implementations are described. For example, for multithreaded decoding, a decoder uses innovations in the areas of layered data structures, picture extent discovery, a picture command queue, and/or task scheduling for multithreading. Or, for a GPU implementation, a decoder uses innovations in the areas of inverse transforms, inverse quantization, fractional interpolation, intra prediction using waves, loop filtering using waves, memory usage and/or performance-adaptive loop filtering. Innovations are also described in the areas of error handling and recovery, determination of neighbor availability for operations such as context modeling and intra prediction, CABAC decoding, computation of collocated information for direct mode macroblocks in B slices, reduction of memory consumption, implementation of trick play modes, and picture dropping for quality adjustment.

A method for decoding an image, and a device using the same are disclosed. The method for decoding an image comprises the steps of: inducing a chroma component block corresponding to a luma component block on the basis of chroma format information indicating chroma component sampling corresponding to luma component sampling; dividing the chroma component block into transformation blocks of a chroma component for transformation on the basis of division information indicating whether a first block has been divided into second blocks for transformation; and acquiring residual information on the transformation blocks of the chroma component by performing at least one of inverse transformation and inverse quantization on the basis of the transformation blocks of the chroma component.

An image decoding method of decoding, on a block-by-block basis, image data included in a coded stream includes: deriving candidates for an intra prediction mode to be used for intra prediction for a decoding target block, the number of the candidates constantly being a plural number; obtaining, from the coded stream, an index for identifying one of the derived candidates for the intra prediction mode; and determining, based on the obtained index, one of the derived candidates for the intra prediction mode as the intra prediction mode to be used for intra prediction for the decoding target block.

An image decoding method of decoding, on a block-by-block basis, image data included in a coded stream includes: deriving candidates for an intra prediction mode to be used for intra prediction for a decoding target block, the number of the candidates constantly being a plural number; obtaining, from the coded stream, an index for identifying one of the derived candidates for the intra prediction mode; and determining, based on the obtained index, one of the derived candidates for the intra prediction mode as the intra prediction mode to be used for intra prediction for the decoding target block.