Method and apparatus for encoding video signal using previous picture already converted into H picture as reference picture of current picture and method and apparatus for decoding such encoded video signal

A method for encoding a video frame sequence divided into a first sub-sequence including frames, which are to be coded into error values, and a second sub-sequence including frames to which the error values are to be added, the method comprising the steps of:

• a) searching for a reference block of an image block included in an arbitrary frame belonging to the first sub-sequence in both a frame present in the second sub-sequence and a frame prior to the arbitrary frame and present in the first sub-sequence, coding an image difference between the image block and the reference block into the image block, and obtaining a motion vector of the image block with respect to the reference block;
• and
• b) selectively performing an operation for adding the image difference between the image block and the reference block to the reference block.

An apparatus for receiving and decoding a first sequence of frames, each including pixels having difference values, and a second sequence of frames into a video signal, the apparatus comprising:

• first means for subtracting difference values of pixels in a target block present in a frame belonging to the first frame sequence from a reference block, based on which the difference values of the pixels in the target block have been obtained, if the reference block is present in a frame belonging to the second frame sequence;
• and
• second means for reconstructing the difference values of the pixels in the target block to an original image of the target block using pixel values of a reference block present in a frame belonging to the second frame sequence or in a frame having an original image reconstructed from a frame including pixels having difference values and belonging to the first frame sequence.

A method for receiving and decoding a first sequence of frames, each including pixels having difference values, and a second sequence of frames into a video signal, the method comprising the steps of:

• a) subtracting difference values of pixels in a target block present in a frame belonging to the first frame sequence from a reference block, based on which the difference values of the pixels in the target block have been obtained, if the reference block is present in a frame belonging to the second frame sequence;
• and
• b) reconstructing the difference values of the pixels in the target block to an original image of the target block using pixel values of a reference block present in a frame belonging to the second frame sequence or in a frame having an original image reconstructed from a frame including pixels having difference values and belonging to the first frame sequence.