Tv-bay Magazine

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BACK TO BASICS Understanding transcoding and its successor: media transformation by Craig Newbury, RadiantGrid, Wohler Technologies Inc. W ith their shift toward use of file-based digital audio and vid- eo, rather than tape- or film-based media, broadcasters and other media companies have moved into a world that demands some familiarity with the concept of media compression. Because the video and audio captured by cameras and microphones often results in very large files with a great deal of information (many, many bits of data), various compression schemes are used to decrease the file size and enable more efficient storage and transport of file-based audio and vid- eo. Well-known compression schemes (formats) include MPEG, Pro-Res, and DNxHD and each of these provides different advantages and disadvantag- es. As their name implies, video and audio “codecs” are the hardware and software systems that handle the compression and decompression of digital video and audio. A codec — and corresponding compression format — typically is selected for how it balances factors such as video quali- ty, the quantity of the data needed to represent it (aka the bit rate), the com- 44 | TV-BAY MAGAZINE: ISSUE 90 JUNE 2014 plexity (and cost) of the encoding and decoding algorithms, robustness to data losses and errors, ease of editing, random access, and end-to-end delay. While the application in which media is being used will help to determine the importance of these elements and, in turn, the optimal file format, the compatibility of file formats with the networks and systems comprising the production and/or distribution chain is also an important consideration. To as- sure that content can be transported, stored, edited, or otherwise processed effectively, many content creation and distribution workflows require, at more and more points, that media files be converted from one format to another. When the flow of audio and video con- tent from system to system requires that an audio or video file be encoded in a different format, “transcoding” is the type of processing applied to convert the file from its current for- mat into the required format — from one encoding scheme to another. Transcoding is also the process that enables content producers and pro- viders to ensure that content meets the specific format requirements of different distribution outlets and target displays. As such, it is a key enabler of the multiplatform media services that bring content to computers and the broad array of mobile viewing devices in use today. The rise of multiplatform media distri- bution has made it necessary for con- tent creators and providers to manage, package, and deliver an unprecedent- ed volume of media. Adding to this challenge is the need to provide this