Context-adaptive variable-length coding (CAVLC) is a form of entropy coding used in H.264/MPEG-4 AVC video encoding. It is used to encode residual, zig-zag order 4x4 (and 2x2) blocks of transform coefficients. As such it is an inherently lossless compression technique. It is primary used as an alternative to Context-based adaptive binary arithmetic coding (CABAC), a more space-efficient entropy encoding scheme, as it requires considerably less processing to decode. CAVLC is supported in all H.264 profiles, unlike CABAC which is not supported in Baseline and Extended profiles.