Coding method, encoder, and decoder

An encoding method, applied to an encoder and comprising:

• determining a context mode flag of a current block;
• determining a height parameter and a width parameter of the current block;
• based on a value of the context mode flag being a first value, determining an initial value of a quantity parameter according to the height parameter, the width parameter, and a first shift parameter;
• and
• based on the value of the context mode flag being a second value, determining the initial value of the quantity parameter according to the height parameter, the width parameter, and a second shift parameter;
• and
• encoding coefficients of the current block using at least one of a context mode or a bypass mode according to the initial value of the quantity parameter to generate a bitstream,
• wherein the first shift parameter and the second shift parameter each are used for right shifting, and the first shift parameter is greater than the second shift parameter.

A decoder, comprising:

• a processor and a memory storing a computer program which, when executed by the processor, causes the processor to:
• decode a bitstream to determine a context mode flag of a current block;
• determine a height parameter and a width parameter of the current block;
• based on a value of the context mode flag being a first value, determine an initial value of a quantity parameter according to the height parameter, the width parameter, and a first shift parameter;
• and
• based on the value of the context mode flag being a second value, determine the initial value of the quantity parameter according to the height parameter, the width parameter, and a second shift parameter;
• and
• determine coefficients of the current block using at least one of a context mode or a bypass mode according to the initial value of the quantity parameter,
• wherein the first shift parameter and the second shift parameter each are used for right shifting, and the first shift parameter is greater than the second shift parameter.