Moving picture coding apparatus and moving picture decoding apparatus
A video encoder ( 70 ) for coding moving pictures comprising a buffer ( 16 c ) with a plurality of memory areas capable of storing frames composed of top fields and bottom fields, a motion estimation unit ( 19 ) operable to code, field by field, inputted pictures performing moving estimation and moving compensation by referring, field by field, to the picture data stored in a memory area, a motion compensation unit ( 16 d ), a subtractor ( 11 ), a transformation unit ( 13 ) and a quantization unit ( 14 ), a memory management unit ( 71 ) operable to manage, frame by frame, a plurality of memory areas, an inverse quantization unit ( 16 a ) and inverse discrete cosine transform unit ( 16 b ) operable to decode picture data in coded fields and store the picture data in the decoded field in any of the plurality of memory areas under the management by the memory management unit ( 71 ).
1. A picture coding and decoding system comprising:
a picture coding apparatus for coding a picture; and
a picture decoding apparatus for decoding a coded picture,
wherein said picture coding apparatus includes:
a memory having a plurality of memory areas, each memory area being capable of storing picture data of a field, or a frame comprising one top field and one bottom field;
a coding unit configured to code the picture on a field by field basis to obtain coded data;
a first decoding unit configured to perform field decoding on the coded data to obtain a decoded field, by referring to a reference field stored in one memory area included in the plurality of memory areas;
a first memory management unit configured to manage each memory area on a frame by frame basis; and
a first storing unit configured to store the decoded field into one memory area included in the plurality of memory areas under management of the first memory management unit, and
wherein said picture decoding apparatus includes:
a memory having a plurality of memory areas, each memory area being capable of storing picture data of a field, or a frame comprising one top field and one bottom field;
a second decoding unit configured to perform field decoding on the coded data to obtain a decoded field, by referring to a reference field stored in one memory area included in the plurality of memory areas;
a second memory management unit configured to manage each memory area on a frame by frame basis and configured to manage a state of each memory area, the state being a state of “used” or a state of “unused”; and
a second storing unit configured to store the decoded field into one memory area included in the plurality of memory areas under management of the second memory management unit,
wherein, when the top field is a reference field and is stored in one memory area included in the plurality of memory areas with a state of “used”, said second memory management unit:
(i) allows the bottom field to be stored in the one memory area into which the top field is stored when the top field and the bottom field constitute a same frame and the bottom field is a reference field, and sets a state corresponding to the one memory area to be a state of “used”; and
(ii) prohibits the bottom field from being stored in the one memory area into which the top field is stored and allows the bottom field to be stored in another memory area other than the one memory area and included in the plurality of memory areas when the bottom field is a reference field but the top field and the bottom field do not constitute a same one frame, and sets a state corresponding to the another memory area other than the one memory area to be a state of “used”.