- A video codec is an electronic circuit or software that compresses or decompresses digital video.
- It converts raw(uncompressed) digital video to a compressed format or vice versa.
- In the context of video compression, "codec" is a concatenation of "encoder" and "decoder" a 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.
- The compression is typically lossy, meaning that the compressed video lacks some information present in the original video.
- In the earlier video was stored as an analog signal on magnetic tape, now we are using compact disc.
- The ratios of information stores in these different channels in the following way Y:Cb:Cr.
- Different codecs use different subsampling ratios as appropriate to their compression needs.
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