Intra-frame coding

Intra-frame coding is a data compression technique used within a video frame, enabling smaller file sizes and lower bitrates, with little or no loss in quality.

Intra-frame prediction exploits spatial redundancy, i.e. correlation among pixels within one frame, by calculating prediction values through extrapolation from already coded pixels for effective delta coding.

Its counterpart is inter-frame prediction which exploits temporal redundancy.

Block-based (frequency transform) formats prefill whole blocks with prediction values extrapolated from usually one or two straight lines of pixels that run along their top and left borders.

The coding process varies greatly depending on which type of encoder is used (e.g., JPEG or H.264), but the most common steps usually include: partitioning into macroblocks, transformation (e.g., using a DCT or wavelet), quantization and entropy encoding.