Picture coding and decoding
A picture with multiple slices is encoded by generating a coded slice representation for each of the slices. A slice flag is set to a first value for the first slice in the picture and corresponding slice flags of the remaining slices are set to a second defined value. A respective slice address is generated for each remaining slice to enable identification of the slice start position within the picture for the slice. A coded picture representation of the picture comprises the coded slice representations, the slice addresses and the slice flags. The slice flags enable differentiation between slices for which slice addresses are required and the slice per picture for which no slice address is needed to identify its slice start position.
1. A method of decoding a picture comprising two or more slices, the two or more slices comprising a first slice in the picture and one or more remaining slices in the picture, the method comprising:
for each slice of the two or more slices:
receiving a slice flag associated with the slice;
determining a value of the received slice flag associated with the slice;
when the value of the received slice flag associated with the slice is determined to be a first defined value which indicates that the slice is the first slice in the picture, determining an associated slice start address in the picture for the first slice in the picture; and
when the value of the received slice flag associated with the slice is determined to be a second defined value which indicates that the slice is one of the one or more remaining slices in the picture, retrieving a slice address for the one of the one or more remaining slices in the picture, and, determining an associated slice start address in the picture for the one of the one or more remaining slices in the picture based on the retrieved slice address, whereby the associated slice start address allows identification of a position of a first coding unit in the slice within the picture;
receiving a coded slice representation of the slice; and
determining, based on the received coded slice representation, pixel values of pixels for the slice; and
wherein, the slice address of the one of the one or more remaining slices is signaled with a fixed length code.
2. The method according to claim 1 , wherein a length of the slice address, in terms of number of bits, is determined as ceil(log 2 (P)), wherein ceil( ) denotes the ceiling function defined as ceil(x)=[x] and outputs the smallest integer not less than x, and, P denotes a total number of possible slice addresses in said picture.
3. The method according to claim 2 , wherein the length of the slice address is determined based at least in part on a total size of the picture.
4. The method according to claim 2 , wherein the picture comprises multiple largest coding units, which have a selected size in terms of number of pixels and can be hierarchically split into multiple coding units having respective sizes that are smaller than the selected size, and further wherein:
a length of the slice address, in terms of number of bits, is determined based on a hierarchical granularity selected for the picture, the hierarchical granularity defining a hierarchical level for slice border alignment within the picture, where the hierarchical level defines a size of a smallest possible addressable coding unit at which a start of a slice of the two or more slices in the picture can be aligned.
5. The method according to claim 1 , wherein the picture comprises multiple largest coding units, which have a selected size in terms of number of pixels and can be hierarchically split into multiple coding units having respective sizes that are smaller than the selected size, and further wherein:
a length of the slice address, in terms of number of bits, is determined based on a hierarchical granularity selected for the picture, the hierarchical granularity defining a hierarchical level for slice border alignment within the picture, where the hierarchical level defines a size of a smallest possible addressable coding unit at which a start of a slice of the two or more slices in the picture can be aligned.
6. The method according to claim 4 , wherein the length of the slice address has been determined based on the hierarchical granularity and based on a total number of largest coding units in the picture.
7. A device for decoding a picture comprising two or more slices, the two or more slices comprising a first slice in the picture and one or more remaining slices in the picture, the device comprising:
circuitry configured to:
for each slice of the two or more slices:
receive a slice flag associated with the slice;
determine a value of the received slice flag associated with the slice;
when the value of the received slice flag associated with the slice is determined to be a first defined value which indicates that the slice is the first slice in the picture, determine an associated slice start address in the picture for the first slice in the picture; and
when the value of the received slice flag associated with the slice is determined to be a second defined value which indicates that the slice is one of the one or more remaining slices in the picture, determine an associated slice start address in the picture for the one of the one or more remaining slices in the picture, whereby the associated slice address allows identification of a position of a first coding unit in the slice within the picture;
receive a coded slice representation of the slice; and
determine, based on the received coded slice representation, pixel values of pixels for the slice;
wherein, the slice address of the one of the one or more remaining slices is signaled with a fixed length code.
8. The device according to claim 7 , wherein the circuitry is further configured to determine a length of the slice address in terms of number of bits as ceil(log 2 (P)), wherein ceil( ) denotes the ceiling function defined as ceil(x)=[x] and outputs the smallest integer not less than x, and, P denotes a total number of possible slice addresses in said picture.
9. The device according to claim 8 , wherein the length of the slice address is determined based at least in part on a total size of the picture.
10. The device according to claim 8 , wherein said picture comprises multiple largest coding units, which have a selected size in terms of number of pixels and can be hierarchically split into multiple coding units having respective sizes that are smaller than said selected size, wherein the circuitry is further configured to:
determine a length of the slice address, in terms of number of bits, based on a hierarchical granularity selected for the picture, the hierarchical granularity defines a hierarchical level for slice border alignment within the picture, where the hierarchical level defines a size of a smallest possible addressable coding unit at which a start of a slice of the two or more slices in the picture can be aligned.
11. The device according to claim 7 , wherein said picture comprises multiple largest coding units, which have a selected size in terms of number of pixels and can be hierarchically split into multiple coding units having respective sizes that are smaller than said selected size, wherein the circuitry is further configured to:
determine a length of the slice address, in terms of number of bits, based on a hierarchical granularity selected for the picture, the hierarchical granularity defines a hierarchical level for slice border alignment within the picture, where the hierarchical level defines a size of a smallest possible addressable coding unit at which a start of a slice of the two or more slices in the picture can be aligned.
12. The device according to claim 9 , wherein the circuitry is further configured to determine the length of the slice address based on the hierarchical granularity and based on a total number of largest coding units in the picture.
13. The device according to claim 7 , wherein the device further comprises one or more of:
a display;
an input port;
an output port; and
a transceiver.
14. The device according to claim 8 , wherein the device further comprises one or more of:
a display;
an input port;
an output port; and
a transceiver.
15. A media terminal comprising a device for decoding a picture according to claim 7 .
16. A media terminal comprising a device for decoding a picture according to claim 8 .
17. A media terminal comprising a device for decoding a picture according to claim 9 .
18. A media terminal comprising a device for decoding a picture according to claim 10 .
19. A media terminal comprising a device for decoding a picture according to claim 12 .
20. A media terminal comprising a device for decoding a picture according to claim 14 .