Updated 24/11/2012Home » Video Glossary » Transcoding


Transcoding is the direct digital-to-digital data conversion of one encoding to another, such as for movie data files or audio files. This is usually done in cases where a target device does not support the format or has limited storage capacity that mandates a reduced file size, or to convert incompatible or obsolete data to a better-supported or modern format.

Transcoding can be performed just while files are being searched, as well as for presentation. For example, Cineon and DPX files have been widely used as a common format for digital cinema, but the data size of a two-hour movie is about 8 terabytes (TB). That large size can increase the cost and difficulty of handling movie files. However, transcoding into a JPEG2000 lossless format has better compression performance than other lossless coding technologies, and in many cases, JPEG2000 can compress images to half-size.

Transcoding is commonly a lossy process, introducing generation loss; however, transcoding can be lossless if the input is losslessly compressed and the output is either losslessly compressed or uncompressed. The process of lossy-to-lossy transcoding introduces varying degrees of generation loss. In other cases, the transcoding of lossy to lossless or uncompressed is technically a lossless conversion because no information is lost, however the process is irreversible and is more suitably known as destructive.