Image coding method, image decoding method, image coding apparatus, image decoding apparatus, and image coding and decoding apparatus
A dependency indication is signaled within the beginning of a packet, that is, within the adjacent of a slice header to be parsed or a parameter set. This is achieved, for example, by including the dependency indication at the beginning of the slice header, preferably after a syntax element identifying the parameter set and before the slice address, by including the dependency indication before the slice address, by providing the dependency indication to a NALU header using a separate message, or by using a special NALU type for NALUs carrying dependent slices.
1. An image decoding method of performing decoding processing of a picture on a slice basis, the image decoding method comprising:
extracting, from a coded bitstream:
a dependent slice enabling flag indicating whether or not a dependent slice is enabled for the picture, wherein the dependent slice is a slice on which the decoding processing is performed by partially using control information included in a header of a slice different from the dependent slice,
a slice address indicating a starting position of a current slice of the picture, and
a dependency indication indicating whether or not the current slice is the dependent slice;
wherein, when the dependency indication indicates the slice is an independent slice, a context table of arithmetic decoding is initialized,
when the dependency indication indicates the slice is the dependent slice, the context table of arithmetic decoding is not initialized,
the dependent slice enabling flag is disposed in a parameter set common to all slices of the picture,
the slice address is disposed in a slice header of the current slice, and
the dependency indication is disposed in the slice header of the current slice before the slice address and after a syntax element identifying the parameter set.
2. The image decoding method according to claim 1 , wherein the dependency indication is extracted from the bitstream when the dependent slice enabling flag indicates the dependent slice is enabled for the picture.
3. The image decoding method according to claim 1 , wherein the dependent slice enabling flag is disposed at a beginning of the parameter set.
4. The image decoding method according to claim 1 , wherein the dependency indication is not included in a slice header of a slice which is processed first for the picture.
5. The image decoding method according to claim 1 , wherein the decoding of the dependent slice does not initialize CABAC context tables.
6. The image decoding method according to claim 1 , wherein the decoding of the slice different from the dependent slice initializes CABAC context tables.
7. An image decoding apparatus which performs decoding processing of a picture on a slice basis, the image decoding apparatus comprising:
a decoder, which extracts from a coded bitstream:
a dependent slice enabling flag indicating whether or not a dependent slice is enabled for the picture, wherein the dependent slice is a slice on which the decoding processing is performed by partially using control information included in a header of a slice different from the dependent slice,
a slice address indicating a starting position of a current slice of the picture, and
a dependency indication indicating whether or not the current slice is the dependent slice;
wherein, when the dependency indication indicates the slice is an independent slice, a context table of arithmetic decoding is initialized,
when the dependency indication indicates the slice is the dependent slice, the context table of arithmetic decoding is not initialized,
the dependent slice enabling flag is disposed in a parameter set common to all slices of the picture,
the slice address is disposed in a slice header of the current slice, and
the dependency indication is disposed in the slice header of the current slice before the slice address and after a syntax element identifying the parameter set.