by Craig Newbury Issue 90 - June 2014
With their shift toward use of file-based digital audio and video, 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 video. Well-known compression schemes (formats) include MPEG, Pro-Res, and DNxHD and each of these provides different advantages and disadvantages.
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 quality, the quantity of the data needed to represent it (aka the bit rate), the complexity (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 assure 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 content 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 format into the required format from one encoding scheme to another. Transcoding is also the process that enables content producers and providers 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 distribution has made it necessary for content creators and providers to manage, package, and deliver an unprecedented volume of media.
Adding to this challenge is the need to provide this content in a broad variety of formats, and in numerous profiles sets of specific parameters within those formats. The automation of transcoding processes has helped to reduce the time and cost involved in handling these tasks, but it has become clear that a more sophisticated approach to managing file-based media and the processing applied to that media can yield significant operational and business benefits. The concept of media transformation responds to this need, building on the value provided by transcoding to enable more efficient and streamlined processing of file-based media across the entire workflow. Ultimately, this approach supports an optimized media pipeline that maximizes the quality of both media assets and the operations outputs.
Rather than simply convert files from one format to another, media transformation solutions extract, index, and leverage intelligence about media files in order to automate key media management and processing steps required to hit the target output parameters. Whats more, with such a solution, the content creator or provider can simply, quickly, and affordably ensure that as media is ingested, transcoded, edited, and otherwise transformed for distribution, the quality and value of that content is maintained, or even enhanced. For example, the solution might adjust (normalize) the audio structure to assure that it meets technical and/or regulatory requirements; adjust video to make sure that it meets broadcast gamut color requirements; and ensure that closed caption data is properly displayed for the target distribution outlet and end-user device.
Within a typical media transformation workflow, content is stored within a single system or repository. A pool of central processing unit (CPU)/graphics processing unit (GPU) resources provides the processing power for transformational algorithms incorporated into the media transformation platform. The processes effectively run on a single system built on commodity IT resources rather than on more expensive to buy and to maintain discrete dedicated processing systems.
Though transcoding plays a central role in virtually every media facility today, media transformation supports a more holistic and ultimately more cost-effective approach to audio and video processing. With this approach to managing file-based assets, content creators and providers can prepare and deliver media with a much greater degree of efficiency and accuracy, both critical capabilities in todays competitive multiplatform media marketplace.