The Transformation Transcoding
Speed or Quality? Why Not Both?
The testing involved a series of clips and output formats that were chosen for their ability to tax different parts of the transcoding process, from random movement to deinterlacing to varying origin sizes. For general purpose computing solutions that rely on a CPU, the newer Nehalem and Westmere Intel chips are adequate when it comes to providing speed and quality for single encodes to a limited number of output formats.
But what about those instances in which the required number of outputs rises significantly? To test this out, we ran each test in a series of incrementally rising output: starting with nine web and IPTV outputs, we then tested 23 mobile outputs and, finally, all of the outputs at the same time, for a total of 32 outputs at one time.
For this kind of heavy lifting, the initial results indicate that specialised solutions, such as those that combine CPU- and ASIC-based processing, can best marry the benefits of general-purpose processing and high-throughput specialty silicon. RGB Networks' recent acquisition of RipCode, for instance, rounded out the company's carrier-class video gateways-ideal for MPEG-2 and H.264-with RipCode's ability to provide CPU-based transcoding for the yet-to-be-standardised screen sizes and bitrates inherent in the Wild West of mobile video delivery. Optibase, recently acquired by VITEC Multimedia, appears to be headed toward a similar complementary model to VITEC's current product offerings.
Workflow Changes
I'll also briefly mention a few workflow changes that are emerging.
Watch Folders: So Yesterday
Speed is queen to quality's king. But today's best transcoding solutions also include a jack of all trades: analytics.
In order to eliminate human or high-touch bottlenecks, top-shelf transcoding solutions offer analysis, transcoding and distribution.
The latter two have been part of desktop transcoding for more than a decade. But even today's desktop transcoding solutions lack the analysis function that most mid- and high-level transcoding solutions offer: the ability to move beyond rigidly defined watch folders and more into ad-hoc analysis of content, with subsequent transcoding based on analysis outcome.
If that sounds confusing, here's an attempt at a simple explanation of the difference between watch folders and analysis:
Watch folders have been used, from the outset, to perform a particular set of transcoding functions. The traditional approach was to set up a watch folder named "web" and define the transcoding to convert any file added to the folder into one or more web formats.
To work properly, though, all original content added to a single watch folder had to share similar traits: a supported codec from which to transcode the output, a similar pixel size, a similar frame rate, and either interlaced or progressive content (but not both).
Mixing and matching content in the same watch folder was a sure guarantee for job failure, which often affected all of the remaining original files in the watch folder: if the failure occurred on the topmost original video file, a transcoding job might shut down immediately. Even for those systems that skipped over failed jobs and continued transcoding the remaining video files in the watch folder, the task of manually finding and deleting the errant output files was highly daunting for even medium-level workloads.
Enter the analysis segment, accompanied by a user-friendly graphical user interface (GUI), of which Inlet's Armada and Telestream's Vantage are prime examples. In today's robust transcoding systems, a GUI can be used to lay out a visual workflow of files from one or multiple watch folders.
Do you need to analyse original files to see if they are progressive or interlaced content? Add a box in the visual workflow that is linked to two other boxes, each with a possible outcome (progressive or interlaced).
Want to further parse the progressive content into 24 frames per second (fps) versus 25 fps? Add a second pair of boxes to the visual workflow, one for 24 fps content and another for 25 fps content.
Finally, add one transcode step for each of the decision boxes, as well as a location box for each of the output files, and suddenly the watch folder can handle a much wider variety of content, with intelligence built in to the workflow.
Companies and Suppliers Mentioned