Video decoding method and apparatus

A video decoding apparatus comprising:

• a decoder to decode video encoded data using a predictive picture signal for a video signal to generate a decoded picture signal;
• a compression unit configured to compress the decoded picture signal to generate a compressed picture signal;
• a first memory to store the decoded picture signal;
• a second memory to store the compressed picture signal, such that the first memory stores the decoded picture signal, and the second memory stores the compressed picture signal, which a compressed version of the decoded picture signal stored in the first memory;
• a decompression unit configured to decompress the compressed picture signal read from the second memory to generate a compressed/decompressed picture signal;
• a selector to select one of the decoded picture signal read from the first memory and the compressed/decompressed picture signal as a reference picture signal according to at least one of a coding type of the video encoded data in picture unit and a prediction mode in block unit;
• a third memory to store the reference picture signal;
• and
• a motion compensator to perform motion compensation on the reference picture signal to generate a predictive picture signal, wherein
• the selector is to select the decoded picture signal read from the first memory at the time that the prediction mode in block unit indicates a mode for generating the predictive picture signal from a forward prediction pixel block, and is to select two reference blocks of the compressed/decompressed picture signal at the time that the prediction mode in block unit indicates a mode for generating the predictive picture signal from a dual prime prediction pixel block.

A non-transitory tangible computer readable storage medium storing instructions of a computer program which when executed by a computer results in performance of steps comprising:

• decoding video encoded data using a predictive picture signal for a video signal to generate a decoded picture signal;
• compressing the decoded picture signal to generate a compressed picture signal;
• storing the decoded picture signal in a first memory;
• storing the compressed picture signal, which is a compressed version of the decoded picture signal stored in the first memory, in a second memory;
• decompressing the compressed picture signal read from the second memory to generate a compressed/decompressed picture signal;
• selecting one of the decoded picture signal read from the first memory and the compressed/decompressed picture signal as a reference picture signal according to at least one of a coding type of the video encoded data in picture unit and a prediction mode in block unit;
• storing the reference picture signal in a third memory;
• and
• performing motion compensation on the reference picture signal to generate a predictive picture signal, wherein
• the selecting includes selecting the decoded picture signal read from the first memory at the time that the prediction mode in block unit indicates a mode for generating the predictive picture signal from a forward prediction pixel block, and selecting two reference blocks of the compressed/decompressed picture signal at the time that the prediction mode in block unit a mode for generating the predictive picture signal from a dual prime prediction pixel block.