Encoding method and decoding method, and device implementing the same
An encoding method obtains an intra prediction mode related to a current block from a bitstream; obtains prediction samples of the current block by performing intra prediction on the current block based on the intra prediction mode; scans transform coefficients of the current block, obtains dequantized transform coefficients of the current block by performing a dequantization on the transform coefficients; determines a transform type of the current block; and obtains residual samples of the current block by performing an inverse-transform on the dequantized transform coefficients based on the determined transform type, the inverse-transform being performed in a horizontal direction and a vertical direction. The transform type is determined to be a Discrete Cosine Transform or Discrete Sine Transform, the size of the current block is equal to or greater than 4×4, and the transform type is determined independently to a direction of the intra prediction mode of the current block.
1. A video decoding method, the method comprising:
obtaining an intra prediction mode related to a current block from a bitstream;
obtaining prediction samples of the current block by performing intra prediction on the current block based on the intra prediction mode;
scanning transform coefficients of the current block,
obtaining dequantized transform coefficients of the current block by performing a dequantization on the transform coefficients;
determining a transform type of the current block; and
obtaining residual samples of the current block by performing an inverse-transform on the dequantized transform coefficients based on the determined transform type, the inverse-transform being performed in a horizontal direction and a vertical direction,
wherein the transform type is determined to be a DCT (Discrete Cosine Transform) or a DST (Discrete Sine Transform),
wherein when a size of the current block is 4×4 the DST is applied both in the horizontal direction and the vertical direction for all intra prediction direction mode and a planar mode of the current block.
2. A video encoding method, the method comprising:
scanning transform coefficients of a current block;
obtaining dequantized transform coefficients of the current block by performing a dequantization on transform coefficients;
determining a transform type of the current block; and
obtaining residual samples of the current block by performing an inverse-transform on the dequantized transform coefficients based on the determined transform type, the inverse-transform being performed in a horizontal direction and a vertical direction,
wherein the transform type is determined to be a DCT (Discrete Cosine Transform) or a DST (Discrete Sine Transform),
wherein when a size of the current block is 4×4 the DST is applied both in the horizontal direction and the vertical direction for all intra prediction direction mode and a planar mode of the current block.
3. A method for transmitting a bitstream, the method comprising:
scanning transform coefficients of a current block;
obtaining dequantized transform coefficients of the current block by performing a dequantization on transform coefficients;
determining a transform type of the current block; and
obtaining residual samples of the current block by performing an inverse-transform on the dequantized transform coefficients based on the determined transform type, the inverse-transform being performed in a horizontal direction and a vertical direction,
wherein the transform type is determined to be a DCT (Discrete Cosine Transform) or a DST (Discrete Sine Transform),
wherein when a size of the current block is 4×4 the DST is applied both in the horizontal direction and the vertical direction for all intra prediction direction mode and a planar mode of the current block.