Standard Hybrid Video Codec Terminology

Based on the sidebar inset article of Rate-distortion optimization paper.

Prediction mode: A method which is selected for use in approximating a picture region.

Block: A rectangular region (normally of size 8 x 8) in a picture. The Discrete Cosine Transform (DCT) in standard video coders always operates on 8 x 8 block regions.

Macroblock: A region of size 16 x 16 in the luminance picture which is associated with a prediction mode.

Motion vector (MV): A spatial displacement offset for use in the prediction of an image region. In the INTER prediction mode, an MV affects a macroblock region, while in the INTER+4V prediction mode, an individual MV is sent for each of the four 8 x 8 blocks in a macroblock.

INTRA mode: A prediction mode in which the picture content of a macroblock region is represented without reference to a region in any previously decoded picture.

SKIP mode: A prediction mode in which the picture content of a macroblock region is represented as a copy of the macroblock in the same location in a previously decoded picture.

INTER mode: A prediction mode in which the picture content of a macroblock region is represented as the sum of a motion-compensated prediction using a motion vector, plus (optionally) a decoded residual difference signal representation.

INTER+4V mode: A prediction mode in which the picture content of a macroblock region is represented as in the INTER mode, but using four motion vectors (one for each 8 x 8 block in the macroblock).

INTER+Q mode: A prediction mode in which the picture content of a macroblock is represented as in the INTER mode, and a change is indicated for the inverse quantization scaling of the decoded residual signal representation.