Moving picture decoding apparatus and picture boundary deciding method

1. A moving picture decoding apparatus for receiving stream data which includes slice pictures and for decoding the slice pictures to reproduce a moving picture, wherein the slice pictures include, as attribute information, a delimiter indicating a picture boundary, and frame number control information indicating whether an increment in frame_num is limited to 0 or 1, the apparatus comprising:

a first decision unit which decides whether the delimiter exists, and which decides that a position of the delimiter is the picture boundary when it is decided that the delimiter exists;

a second decision unit which decides whether an increment in frame_num is 1 or more than 1, when the first decision unit decides that no delimiter exists, and which decides that a boundary between a current slice picture and a preceding slice picture is the picture boundary, when deciding that the increment in frame_num is 1; and

a controller which discards the current slice picture when the first decision unit decides that no delimiter exists, and the second decision unit decides that the increment in frame_num is more than 1.

2. The moving picture decoding apparatus according to claim 1 , further comprising a third decision unit which decides whether data items nal_ref_idc added to the current and preceding slice pictures differ from each other, when the second decision unit decides that the increment in fram_num is 0, and which decides that the boundary between the current slice picture and the preceding slice picture is the picture boundary, when deciding that the data items nal_ref_idc differ from each other, wherein the data items nal_ref_idc indicate whether each of the current and preceding slice pictures should be used as a reference picture.

3. The moving picture decoding apparatus according to claim 2 , wherein when deciding that the data items nal_ref_idc differ from each other, the third decision unit further decides whether the data item nal_ref_idc added to the preceding slice picture is 0, and decides that the boundary between the current slice picture and the preceding slice picture is the picture boundary, when deciding that the data item nal_ref_idc added to the preceding slice picture is 0.

4. The moving picture decoding apparatus according to claim 1 , further comprising a third decision unit which decides whether data items nal_ref_idc added to the current and preceding slice pictures differ from each other, when the second decision unit decides that the increment in frame_num is 0, and which decides that the boundary between the current slice picture and the preceding slice picture is the picture boundary, when deciding that the data items nal_ref_idc differ from each other and the data item nal_ref_idc added to the preceding slice picture is 0, wherein the data items nal_ref_idc indicate whether each of the current and preceding slice pictures should be used as a reference picture.

5. The moving picture decoding apparatus according to claim 1 , further comprising a third decision unit which decides whether data items nal_ref_idc added to the current and preceding slice pictures differ from each other, when the second decision unit decides that the increment in frame_num is 0, and which sets the data item nal_ref_idc added to the current slice picture to a same value as the data item nal_ref_idc added to the preceding slice picture, when deciding that the data items nal_ref_idc differ from each other and the data item nal_ref_idc added to the preceding slice picture is not 0, wherein the data items nal_ref_idc indicate whether each of the current and preceding slice pictures should be used as a reference picture.

6. A moving picture decoding method for a moving picture decoding apparatus which receives stream data including slice pictures and which decodes the slice pictures to reproduce a moving picture, wherein the slice pictures include, as attribute information, a delimiter indicating a picture boundary, and frame_number control information indicating whether an increment in frame_num is limited to 0 or 1, the method comprising:

deciding whether the delimiter exists, and deciding that a position of the delimiter is the picture boundary when it is decided that the delimiter exists;

deciding whether an increment in frame_num is 1 or more than 1, when it is decided that no delimiter exists, and deciding that a boundary between a current slice picture and a preceding slice picture is the picture boundary, when deciding that the increment in frame_num is 1; and

discarding the current slice picture when it is decided that no delimiter exists, and that the increment in frame_num is more than 1.

7. The moving picture decoding method according to claim 6 , further comprising deciding whether data items nal_ref_idc added to the current and preceding slice pictures differ from each other, when it is decided that the increment in fram num is 0, and deciding that the boundary between the current slice picture and the preceding slice picture is the picture boundary, when it is decided that the data items nal_ref_idc differ from each other, wherein the data items nal_ref_idc indicate whether each of the current and preceding slice pictures should be used as a reference picture.

8. The moving picture decoding method according to claim 7 , wherein when deciding whether the data items nal_ref_idc differ from each other, it is further decided whether the data item nal_ref_idc added to the preceding slice picture is 0, and it is decided that the boundary between the current slice picture and the preceding slice picture is the picture boundary, when it is decided that the data item nal_ref_idc added to the preceding slice picture is 0.

9. The moving picture decoding method according to claim 6 , further comprising deciding whether data items nal_ref_idc added to the current and preceding slice pictures differ from each other, when it is decided that the increment in frame_num is 0, and deciding that the boundary between the current slice picture and the preceding slice picture is the picture boundary, when it is decided that the data items nal_ref_idc differ from each other and the data item nal_ref_idc added to the preceding slice picture is 0, wherein the data items nal_ref_idc indicate whether each of the current and preceding slice pictures should be used as a reference picture.

10. The moving picture decoding method according to claim 6 , further comprising deciding whether data items nal_ref_idc added to the current and preceding slice pictures differ from each other, when it is decided that the increment in frame_num is 0, and setting the data item nal_ref_idc added to the current slice picture to a same value as the data item nal_ref_idc added to the preceding slice picture, when deciding that the data items nal_ref_idc differ from each other and the data item nal_ref_idc added to the preceding slice picture is not 0, wherein the data items nal_ref_idc indicate whether each of the current and preceding slice pictures should be used as a reference picture.

11. A moving picture decoding apparatus for receiving stream data which includes slice pictures and for decoding the slice pictures to reproduce a moving picture, wherein the slice pictures include, as attribute information, a delimiter indicating a picture boundary, and frame_number control information indicating whether an increment in frame_num is limited to 0 or 1, the apparatus comprising:

first decision means for deciding whether the delimiter exists, and for deciding that a position of the delimiter is the picture boundary when it is decided that the delimiter exists;

second decision means for deciding whether an increment in frame_num is 1 or more than 1, when the first decision means decides that no delimiter exists, and for deciding that a boundary between a current slice picture and a preceding slice picture is the picture boundary, when deciding that the increment in frame_num is 1; and

control means for discarding the current slice picture when the first decision means decides that no delimiter exists, and the second decision means decides that the increment in frame_num is more than 1.

12. The moving picture decoding apparatus according to claim 11 , further comprising third decision means for deciding whether data items nal_ref_idc added to the current and preceding slice pictures differ from each other, when the second decision means decides that the increment in fram num is 0, and for deciding that the boundary between the current slice picture and the preceding slice picture is the picture boundary, when deciding that the data items nal_ref_idc differ from each other, wherein the data items nal_ref_idc indicate whether each of the current and preceding slice pictures should be used as a reference picture.

13. The moving picture decoding apparatus according to claim 12 , wherein when deciding the data items nal_ref_idc differ from each other, the third decision means further decides whether the data item nal_ref_idc added to the preceding slice picture is 0, and decides that the boundary between the current slice picture and the preceding slice picture is the picture boundary, when deciding that the data item nal_ref_idc added to the preceding slice picture is 0.

14. The moving picture decoding apparatus according to claim 11 , further comprising third decision means for deciding whether data items nal_ref_idc added to the current and preceding slice pictures differ from each other, when the second decision means decides that the increment in frame_num is 0, and for deciding that the boundary between the current slice picture and the preceding slice picture is the picture boundary, when deciding that the data items nal_ref_idc differ from each other and the data item nal_ref_idc added to the preceding slice picture is 0, wherein the data items nal_ref_idc indicate whether each of the current and preceding slice pictures should be used as a reference picture.

15. The moving picture decoding apparatus according to claim 11 , further comprising third decision means for deciding whether data items nal_ref_idc added to the current and preceding slice pictures differ from each other, when the second decision means decides that the increment in frame_num is 0, and for setting the data item nal_ref_idc added to the current slice picture to a same value as the data item nal_ref_idc added to the preceding slice picture, when deciding that the data items nal_ref_idc differ from each other and the data item nal_ref_idc added to the preceding slice picture is not 0, wherein the data items nal_ref_idc indicate whether each of the current and preceding slice pictures should be used as a reference picture.