Encoding and decoding method and apparatus thereof

An encoding method for dividing video data processed according to an interlace scanning method into blocks, each of which has a predetermined magnitude, and encoding the respective divided block data, said method comprising the steps of:

• (a) discriminatively arranging the block data into block data of a frame pattern and a field pattern;
• (b) receiving the block data of the frame pattern and the block data of the field pattern, discrete-cosine-transforming the respective received data and quantizing the discrete-cosine-transformed data;
• (c) receiving the block data of the frame pattern, the block data of the field pattern and motion compensated data, discrete-cosine-transforming the respective received data and quantizing the discrete-cosine-transformed data;
• (d) accumulatively counting the number of bits of the block unit according to the respective run-length level which is generated during said steps (b) and (c);
• (e) comparing the respective count results with one another so as to select a mode which generated a smallest number of the bits;
• (f) delaying the first and second quantized data by a predetermined time during the mode selection according to steps (d) and (e);
• (g) selectively outputting the delayed quantized data according to the selected mode;
• (h) modulating by direct current (DC) differential pulse code modulation (DCPM) data corresponding to the selected mode;
• (i) coding the DC DPCM data;
• and
• (j) restoring the DC DPCM data.

A decoding apparatus for decoding inversely quantized video data into a state prior to being encoded, by using an inverse quantizer for inverse-quantizing video data which is divided into blocks each of which has a predetermined magnitude and is encoded by intramode processing or intermode processing according to transmitted quantization level, and motion compensation means, the decoding apparatus comprising:

• input means to which encoded data is input;
• direct current (DC) detection means receiving output data of the inverse quantizer supplied through the input means, a mode selection signal representing said intramode processing or intermode processing and a block DC latch signal representing a block interval of the block data, for detecting DC values of the respective block data;
• and
• video restoring means receiving output data of an inverse discrete cosine transform (DCT) portion, which transforms inverse quantizer output data into a state prior to being discrete-cosine-transformed, DC data output from the DC detection means, motion compensation means output data, the mode selection signal and the block DC selection signal, for outputting an original video signal of which the DC level is restored.

A decoding method for receiving encoded video data and decoding the received encoded video data into an original signal prior to being encoded, the decoding method comprising the steps of:

• (a) detecting direct current values of respective block data from the received video data
• (b) motion-compensating restored block data in correspondence to a motion vector which is calculated from a motion compensator in an encoding apparatus;
• (c) discriminatively arranging the motion compensated data into frame and field patterns;
• and
• (d) receiving the DC data and the motion compensated frame/field patterned data and restoring and outputting an original video signal of which the DC level is restored.