Picture coding method and picture decoding method
View Patent ↗An image coding method and an image decoding method is provided by which an image can be restored correctly even if part of memory management information is lost by a transmission channel error, a candidate of a reference image that can be referred to is selected more appropriately, and coding efficiency is improved. The image coding method includes a step for executing coding of an image, a step for judging whether a picture in the memory which is never used as reference exists, a step for coding memory management information for releasing the picture in the memory which is never used as reference when a picture in the memory which is never used as reference exists, a step for releasing the picture in the memory which is never used as reference, a step for judging whether the memory management information that releases the picture in the memory which is never used as reference is coded by coding of an image immediately before, and a step for coding again the memory management information that releases the picture in the memory which is never used as reference when the memory management information is coded.
1. A coding method for coding a moving image including a plurality of pictures, said method comprising:
coding a current picture to output a coded current picture;
coding first memory management information for managing a reference picture stored in a memory, the first memory management information being attached to the coded current picture; and
coding the first memory management information again as second memory management information, the second memory management information being attached to another picture which is different from the current picture,
wherein information that identifies the current picture is attached to the second memory management information.
2. The coding method according to claim 1
wherein the first and second memory management information designate an area of the memory which holds an unnecessary picture and which is therefore to be released.
3. The coding method according to claim 1
wherein the memory includes (i) a short term memory that holds a reference picture for a short period of time and (ii) a long term memory that holds a reference picture for a longer period of time than the short term memory, and
wherein the first and second memory management information designate a reference picture to be moved from the short term memory to the long term memory.
4. A computer readable recording medium on which a data stream is recorded, the data stream being obtained by coding a moving image including a plurality of pictures,
wherein the data stream includes:
a coded current picture generated by coding a current picture to be coded;
coded management information data generated by coding first memory management information for managing a reference picture stored in a memory, the first memory management information being attached to the coded current picture; and
re-coded management information data generated by coding the first memory management information again as second memory management information, the second memory management information being attached to another picture which is different from the current picture,
wherein information that identifies the current picture is attached to the second memory management information.
5. A coding apparatus that codes a moving image including a plurality of pictures, said apparatus comprising:
a picture coding unit operable to code a current picture to be coded to output a coded current picture;
a first management information coding unit operable to code first memory management information for managing a reference picture stored in a memory, the first memory management information being attached to the coded current picture; and
a second management information coding unit operable to code the first memory management information again as second memory management information, the second memory management information being attached to another picture which is different from the current picture,
wherein information that identifies the current picture is attached to the second memory management information.