Video signal processing method and device

A method of decoding a video, the method comprising:

• determining an intra prediction mode of a current block;
• determining a reference sample line of the current block;
• and
• obtaining prediction samples of the current block based on the intra prediction mode and reference samples in the reference sample line,
• wherein when the intra prediction mode of the current block is a directional intra prediction mode, the prediction samples of the current block are derived based on first reference samples, each of the first reference samples being located in a forward direction of the directional intra prediction mode with respect to a corresponding sample to be predicted,
• wherein the method further comprises determining whether to extend the intra prediction mode of the current block bi-directionally,
• wherein when it is determined to extend the intra prediction mode of the current block bi-directionally, prediction samples included in a first region of the current block is modified, and the others of the prediction samples included in a second region of the current block are not modified, a prediction sample in the first region being modified by using a second reference sample located at an opposite direction of the directional intra prediction mode,
• whether to extend the intra prediction mode of the current block bi-directionally is determined based on whether the intra prediction mode of the current block is included in a range pre-defined in a device for decoding the video, and
• wherein when at least one of a width and a height of the current block is less than or equal to a threshold value, the intra prediction mode of the current block is not extended bi-directionally regardless of whether the intra prediction mode of the current block is included in the range or not.

A method of encoding a video, the method comprising:

• obtaining prediction samples of a current block based on an intra prediction mode and reference samples in a reference sample line;
• and
• encoding information on the intra prediction mode and information on the reference sample line of the current block,
• wherein when the intra prediction mode of the current block is a directional intra prediction mode, the prediction samples of the current block are derived based on first reference samples, each of the first reference samples being located in a forward direction of the directional intra prediction mode with respect to a corresponding sample to be predicted,
• wherein the method further comprises determining whether to extend the intra prediction mode of the current block bi-directionally,
• wherein when it is determined to extend the intra prediction mode of the current block bi-directionally, prediction samples included in a first region of the current block is modified, and the others of the prediction samples included in a second region of the current block are not modified, a prediction sample in the first region being modified by using a second reference sample located at an opposite direction of the directional intra prediction mode,
• whether to extend the intra prediction mode of the current block bi-directionally is determined based on whether the intra prediction mode of the current block is included in a range pre-defined in a device for decoding the video, and
• wherein when at least one of a width and a height of the current block is less than or equal to a threshold value, the intra prediction mode of the current block is not extended bi-directionally regardless of whether the intra prediction mode of the current block is included in the range or not.

A device for transmitting compressed video data, comprising:

• a processor to generate the compressed video data;
• and
• a transmitter to transmit the compressed video data,
• wherein generating the compressed video data comprises:
• obtaining prediction samples of a current block based on an intra prediction mode and reference samples in a reference sample line;
• and
• encoding information on the intra prediction mode and information on the reference sample line of the current block,
• wherein when the intra prediction mode of the current block is a directional intra prediction mode, the prediction samples of the current block are derived based on first reference samples, each of the first reference samples being located in a forward direction of the directional intra prediction mode with respect to a corresponding sample to be predicted,
• wherein the method further comprises determining whether to extend the intra prediction mode of the current block bi-directionally,
• wherein when it is determined to extend the intra prediction mode of the current block bi-directionally, prediction samples included in a first region of the current block is modified, and the others of the prediction samples included in a second region of the current block are not modified, a prediction sample in the first region being modified by using a second reference sample located at an opposite direction of the directional intra prediction mode,
• whether to extend the intra prediction mode of the current block bi-directionally is determined based on whether the intra prediction mode of the current block is included in a range pre-defined in a device for decoding the video, and
• wherein when at least one of a width and a height of the current block is less than or equal to a threshold value, the intra prediction mode of the current block is not extended bi-directionally regardless of whether the intra prediction mode of the current block is included in the range or not.