A device that converts video from one format to another, such as VGA to component video.
An electronic device designed to convert one signal type to another, and vice-versa. For example, the Extron YCS Transcoder both decodes composite video into S-video, and encodes S-video into composite video.
A device that converts digital content from one (usually lossy) format to another. It involves first decoding/decompressing the original data to a raw intermediate format (ie. PCM for audio or YUV for video) that mimics standard playback of the lossy content and then re-encoding this into the target format. Compression artifacts are cumulative, therefore transcoding between lossy codecs causes a progressive loss of quality with each successive generation. (source)