Updated April 10, 2017. In grammar, a demonstrative is a determiner or a pronoun that points to a particular noun or to the noun it replaces. There are four demonstratives in English: the near demonstratives this and these, and the far demonstratives that and those. This and that are singular; these and those are plural.
In the context of video compression, codec is a concatenation of encoder and decoderâa device that only compresses is typically called an encoder, and one that only decompresses is a decoder. The compressed data format usually conforms to a standard video compression specification.
2) The term codec is also an acronym that stands for  co mpression/ dec ompression.. A codec is an algorithm, or specialized computer program, that reduces the number of bytes consumed by large files and programs. In order to minimize the amount of storage space required for a complicated file, such as a video, compression is used. Compression works by eliminating redundancies in data.