decodersencoders

Decoders and encoders is a term used to describe devices or algorithms that convert information between representations. Encoding is the process of transforming source data into a coded form for efficient storage, transmission, or processing, while decoding is the reverse operation that recovers the original data. The combined term codec (contraction of coder-decoder) or codec suite is common in multimedia and communications.

In digital logic and electronics, encoders and decoders are fundamental building blocks. An encoder aggregates multiple input lines into a smaller set of outputs, sometimes with priority to handle simultaneous inputs. A decoder takes an n-bit binary value and asserts one of up to 2^n outputs, effectively selecting a line. These components are used for memory addressing, display driving, and routing data in multiplexers and demultiplexers. They can be combined to implement larger logic functions.

In data compression and multimedia, a codec includes an encoder and a decoder that compress and reconstruct data. Encoders reduce redundancy to save bandwidth or space, while decoders revert to a form suitable for playback or use. Codecs may be lossless (PNG, FLAC) or lossy (JPEG, MP3, H.264). The encoding process often involves prediction, transformation, quantization, and entropy coding; decoding mirrors these steps in reverse.

In machine learning, encoder–decoder architectures (or sequence-to-sequence models) map input sequences to a continuous representation and then generate output sequences. They are used in language translation, text summarization, and image-to-text tasks, illustrating another domain where the coder–decoder concept is central.