Encoding and decoding method, bitstream, encoder, decoder, and computer storage medium

An encoding method, performed by an encoder, the method comprising:

• determining last significant coefficient location reverse identification information of a current slice, and a location of a last significant coefficient of a current block of blocks in the current slice;
• determining coordinate information of the last significant coefficient of the current block according to the last significant coefficient location reverse identification information and the location of the last significant coefficient;
• and
• encoding coefficients located above the location of the last significant coefficient in a preset scanning order, and signalling, into a bitstream, bit information obtained through the encoding, the last significant coefficient location reverse identification information, and the coordinate information of the last significant coefficient,
• wherein the location of the last significant coefficient comprises an initial horizontal coordinate and an initial vertical coordinate of the last significant coefficient, the initial horizontal coordinate and the initial vertical coordinate being a horizontal distance and a vertical distance between the location of the last significant coefficient and a top left corner of the current block, respectively,
• wherein determining the coordinate information of the last significant coefficient of the current block according to the last significant coefficient location reverse identification information and the location of the last significant coefficient comprises:
• in response to a value of the last significant coefficient location reverse identification information being a first value, determining the coordinate information of the last significant coefficient by performing calculation on the initial horizontal coordinate and the initial vertical coordinate of the last significant coefficient,
• wherein the method further comprises:
• in response to the value of the last significant coefficient location reverse identification information being the first value, determining the coordinate information of the last significant coefficient to be a horizontal distance and a vertical distance between the location of the last significant coefficient and a bottom right corner of the current block.

An encoder, comprising a first memory and a first processor, wherein

• the first memory is configured to store thereon a computer program executable on the first processor;
• and
• the first processor is configured to execute the computer program to perform:
• determining last significant coefficient location reverse identification information of a current slice, and a location of a last significant coefficient of a current block of blocks in the current slice;
• determining coordinate information of the last significant coefficient of the current block according to the last significant coefficient location reverse identification information and the location of the last significant coefficient;
• and
• encoding coefficients located above the location of the last significant coefficient in a preset scanning order, and signalling, into a bitstream, bit information obtained through the encoding, the last significant coefficient location reverse identification information, and the coordinate information of the last significant coefficient,
• wherein the location of the last significant coefficient comprises an initial horizontal coordinate and an initial vertical coordinate of the last significant coefficient, the initial horizontal coordinate and the initial vertical coordinate being a horizontal distance and a vertical distance between the location of the last significant coefficient and a top left corner of the current block, respectively,
• wherein determining the coordinate information of the last significant coefficient of the current block according to the last significant coefficient location reverse identification information and the location of the last significant coefficient comprises:
• in response to a value of the last significant coefficient location reverse identification information being a first value, determining the coordinate information of the last significant coefficient by performing calculation on the initial horizontal coordinate and the initial vertical coordinate of the last significant coefficient,
• the first processor is further configured to execute the computer program to perform:
• in response to the value of the last significant coefficient location reverse identification information being the first value, determining the coordinate information of the last significant coefficient to be a horizontal distance and a vertical distance between the location of the last significant coefficient and a bottom right corner of the current block.

A decoder, comprising a memory and a processor, wherein

• the memory is configured to store thereon a computer program executable on the processor;
• and
• the processor is configured to execute the computer program to perform:
• determining, by parsing a bitstream, last significant coefficient location reverse identification information of a current slice, and coordinate information of a last significant coefficient of a current block of blocks in the current slice;
• in response to the last significant coefficient location reverse identification information indicating that last significant coefficient location reverse is applied to the blocks in the current slice, obtaining a location of the last significant coefficient of the current block by performing calculation on the coordinate information of the last significant coefficient;
• and
• determining coefficients of the current block by decoding coefficients located above the location of the last significant coefficient in a preset scanning order,
• wherein the processor is further configured to execute the computer program to perform:
• in response to the last significant coefficient location reverse identification information indicating that the last significant coefficient location reverse is applied to the blocks in the current slice, determining the coordinate information of the last significant coefficient of the current block to be a horizontal distance and a vertical distance between the location of the last significant coefficient and a bottom right corner of the current block.