encoder

An encoder is a device or algorithm that converts information from one format to another, typically into a coded or digital representation. Encoders are used to prepare signals for transmission, storage, or processing, and they are generally paired with decoders that perform the reverse operation.

In electronics, encoders translate mechanical position or motion into electrical signals. Rotary encoders yield a digital code corresponding to angular position, while linear encoders do the same for linear travel. They are often classified as incremental (relative position) or absolute (fixed positioning), and employ optical, magnetic, or capacitive sensing.

In data encoding and communications, encoders convert data into formats suitable for transmission or storage. Video and audio encoders compress streams into compact bitstreams, while channel encoders introduce error-detecting or error-correcting codes to improve reliability over imperfect channels.

In information theory and computing, an encoder maps a source message to a codeword in a codebook, aiming to reduce redundancy or enable efficient transmission. Decoding reconstructs the original message, and many systems use encoder–decoder pairs.

In machine learning, an encoder is a neural network component that transforms input data into a lower-dimensional representation. Autoencoders and variational autoencoders use encoders to learn compact representations for reconstruction, clustering, or downstream tasks.