Decoding apparatus, decoding method, program and integrated circuit

A decoding method of decoding a block included in a coded image,

• said decoding method being performed by a decoding apparatus including:
• a first memory unit configured to store pixel data of a reference image that is an image already decoded by the decoding apparatus and is referred to when the block is decoded;
• and
• a second memory unit which has a storage capacity smaller than a storage capacity of the first memory unit and provides a data reading speed faster than data reading speed provided by the first memory unit;
• and
• a third memory unit,
• said decoding method comprising:
• transferring, from the first memory unit to the second memory unit, pixel data in a search area that is a part of the reference image and required to calculate a motion vector for the block;
• calculating the motion vector for the block by repeatedly (i) reading out, from the second memory unit, the pixel data in the search area for the block and (ii) performing a predetermined operation on the pixel data;
• generating a prediction image for the block by using the motion vector and the pixel data in the reference image;
• transferring the pixel data in the reference area that is a part of the reference image and is referred to in said generating, from one of the first and second memory units to the third memory unit;
• and
• decoding the block using the prediction image generated in said generating.

A non-transitory computer-readable recording medium on which a program causing a decoding apparatus to decode a block included in a coded image is recorded,

• the decoding apparatus including:
• a first memory unit configured to store pixel data of a reference image that is an image already decoded by the decoding apparatus and is referred to when the block is decoded;
• and
• a second memory unit which has a storage capacity smaller than a storage capacity of the first memory unit and provides a data reading speed faster than data reading speed provided by the first memory unit;
• and
• a third memory unit,
• said program causing the decoding apparatus to execute:
• transferring, from the first memory unit to the second memory unit, pixel data in a search area that is a part of the reference image and required to calculate a motion vector for the block;
• calculating the motion vector for the block by repeatedly (i) reading out, from the second memory unit, the pixel data in the search area for the block and (ii) performing a predetermined operation on the pixel data;
• generating a prediction image for the block by using the motion vector and the pixel data in the reference image;
• transferring the pixel data in the reference area that is a part of the reference image and is referred to in said generating, from one of the first and second memory units to the third memory unit;
• and
• decoding the block using the prediction image generated in said generating.

An integrated circuit which decodes a block included in a coded image,

• said integrated circuit being included in a decoding apparatus which includes a first memory unit configured to store pixel data of a reference image that is an image already decoded by the decoding apparatus and is referred to when the block is decoded, and
• said integrated circuit comprising:
• a second memory unit which has a storage capacity smaller than a storage capacity of said first memory unit and provides a data reading speed faster than data reading speed provided by said first memory unit;
• a search area transfer unit configured to transfer, from the first memory unit to said second memory unit, pixel data in a search area that is a part of the reference image and required to calculate a motion vector for the block;
• a motion vector operating unit configured to calculate the motion vector for the block by repeatedly (i) reading out, from said second memory unit, the pixel data in the search area for the block and (ii) performing a predetermined operation on the pixel data;
• a motion compensation operating unit configured to generate a prediction image for the block by using the motion vector and the pixel data in the reference image;
• a third memory unit configured to store pixel data of a reference area that is a part of the reference image and is referred to by said motion compensation operating unit;
• a reference area transfer unit configured to transfer the pixel data in the reference area from one of said first and second memory units to said third memory unit;
• and
• a decoding unit configured to decode the block using the prediction image generated by said motion compensation operating unit.