Method and device for encoding and decoding parameter sets at slice level

1. A method for parsing a bitstream, performed by a video decoder, comprising:

parsing a slice header of a current slice to obtain an identifier of a slice-level parameter set comprising information on coding tools used for decoding the current slice;

overwriting, based on a flag, coding tool parameters of a coding tool previously determined for decoding the current slice with coding tool parameters obtained in parsing the slice header; and

decoding the current slice according to the coding tool parameters obtained in parsing the slice header;

wherein the slice-level parameter set is a data structure containing common information of one or more coding tools used in the process of encoding/decoding multiple slices.

2. The method of claim 1 , wherein the overwriting includes:

for the coding tool, if there is only one slice-level parameter set, in which an indication flag of the coding tool is 1, in the slice-level parameter sets referred to by the current slice,

then determining that the coding tool parameters of the coding tool obtained in parsing the slice header are used in the process of decoding the current slice.

3. The method of claim 1 , wherein a binary representation of the flag used for indicating a currently adopted multi-parameter-set overwriting mode contains one or more bits, wherein each bit indicates the multi-parameter-set overwriting mode for one coding tool.

4. The method of claim 1 , wherein the coding tool parameters include filter parameters used during the decoding.

5. A decoder for parsing a bitstream, comprising a processor configured to:

parse a slice header of a current slice to obtain an identifier of a slice-level parameter set comprising information on coding tools used for decoding the current slice;

overwrite, based on a flag, coding tool parameters of a coding tool previously determined for decoding the current slice with coding tool parameters obtained in parsing the slice header; and

decode the current slice according to the coding tool parameters obtained in parsing the slice header;

wherein the slice-level parameter set is a data structure containing common information of one or more coding tools used in the process of encoding/decoding multiple slices.

6. The decoder of claim 5 , wherein the processor is further configured to:

for the coding tool, if there is only one slice-level parameter set, in which an indication flag of the coding tool is 1, in the slice-level parameter sets referred to by the current slice,

then determine that the coding tool parameters of the coding tool obtained in parsing the slice header are used in the process of decoding the current slice.

7. The decoder of claim 5 , wherein a binary representation of the flag used for indicating a currently adopted multi-parameter-set overwriting mode contains one or more bits, wherein each bit indicates the multi-parameter-set overwriting mode for one coding tool.

8. The decoder of claim 5 , wherein the coding tool parameters include filter parameters used during the decoding.

9. A method for generating a bitstream, performed by an encoder, comprising:

encoding a slice-level parameter set comprising information on coding tools used in encoding a current slice;

determining that coding tool parameters of a coding tool previously used for encoding the current slice is to be overwritten;

encoding a slice header of the current slice to include an identifier of the slice-level parameter set, a flag indicating the overwriting and coding tool parameters of the coding tool used for encoding the current slice; and

encoding the current slice according to the coding tool parameters used for encoding the current slice;

wherein the slice-level parameter set is a data structure containing common information of one or more coding tools used in the process of encoding/decoding multiple slices.

10. The method of claim 9 , wherein the overwriting includes:

for the coding tool, if there is only one slice-level parameter set, in which an indication flag of the coding tool is 1, in the slice-level parameter sets referred to by the current slice,

then causing a decoder to determine that the coding tool parameters of the coding tool obtained in parsing the slice header are used in the process of decoding the current slice.

11. The method of claim 9 , wherein a binary representation of the flag used for indicating a currently adopted multi-parameter-set overwriting mode contains one or more bits, wherein each bit indicates the multi-parameter-set overwriting mode for one coding tool.

12. The method of claim 9 , wherein the coding tool parameters include filter parameters used during the decoding.

13. An encoder for generating a bitstream, comprising a processor configured to:

encode a slice-level parameter set comprising information on coding tools used in encoding a current slice;

determine that coding tool parameters of a coding tool previously used for encoding the current slice is to be overwritten;

encode a slice header of a current slice to include an identifier of the slice-level parameter set, a flag indicating the overwriting and coding tool parameters of the coding tool used for encoding the current slice; and

encode the current slice according to the coding tool parameters used for encoding the current slice;

wherein the slice-level parameter set is a data structure containing common information of one or more coding tools used in the process of encoding/decoding multiple slices.

14. The encoder of claim 13 , wherein the overwriting includes:

for the coding tool, if there is only one slice-level parameter set, in which an indication flag of the coding tool is 1, in the slice-level parameter sets referred to by the current slice,

then causing a decoder to determine that the coding tool parameters of the coding tool obtained in parsing the slice header are used in the process of decoding the current slice.

15. The encoder of claim 13 , wherein the coding tool parameters include filter parameters used during the decoding.