Editing Transcoding (section)

{{Short description|Direct digital-to-digital conversion of one encoding to another}}
{{Other uses|Transcode (disambiguation)|H.264/MPEG-4 AVC products and implementations#Transcoding}}
{{Refimprove|date=October 2015}}

'''Transcoding''' is the direct digital-to-digital conversion of one encoding to another,<ref>{{cite web|author1=Margaret Rouse|title=transcoding|url=http://searchmicroservices.techtarget.com/definition/transcoding|access-date=2018-01-14|archive-date=2018-01-14|archive-url=https://web.archive.org/web/20180114183759/http://searchmicroservices.techtarget.com/definition/transcoding|url-status=dead}}</ref> such as for [[video]] data files, audio files (e.g., [[MP3]], [[WAV]]), or [[character encoding]] (e.g., [[UTF-8]], [[ISO/IEC 8859]]). 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,<ref name="SMP">
   "Advancements in Compression and Transcoding: 2008 and Beyond",
   [[Society of Motion Picture and Television Engineers]] (SMPTE),
   2008, webpage: [https://archive.today/20110719180141/https://www.smpte.org/events/smpte_annual_tech/schedule/06wedspm1/ SMPTE-spm].
</ref> or to convert incompatible or obsolete data to a better-supported or modern format.

In the analog video world, 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 [[terabyte]]s (TB).<ref name=SMP/> That large size can increase the cost and difficulty of handling movie files. However, transcoding into a [[JPEG2000]] lossless format has better [[data compression]] performance than other lossless coding technologies; in many cases, JPEG2000 can compress images to half their original size.<ref name=SMP/>

Transcoding is commonly a [[lossy compression|lossy process]], introducing [[generation loss]]; however, transcoding can be lossless if the output is either losslessly compressed or uncompressed.<ref name=SMP/> 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''.