This is usually done in cases where a target device (or workflow) does not support the format or has limited storage capacity that mandates a reduced file size,[2] or to convert incompatible or obsolete data to a better-supported or modern format.
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).
[2] The process of transcoding into a lossy format introduces varying degrees of generation loss, while the transcoding from lossy to lossless or uncompressed is technically a lossless conversion because no information is lost; however, when the conversion is irreversible, it is then more correctly known as destructive.
Transcoding video from most consumer digital cameras can reduce the file size significantly while keeping the quality about the same.
Transcoding is extensively used by home theatre PC software to reduce the usage of disk space by video files.
Real-time transcoding in a many-to-many way (any input format to any output format) is becoming a necessity to provide true search capability for any multimedia content on any mobile device, with over 500 million videos on the web and a plethora of mobile devices.
Before the advent of semiconductors and integrated circuits, realtime resolution and frame rate transcoding between different analog video standards was achieved by a CRT/camera tube combination.