Supporting advanced transcoding requirements
Written By: Kirk Marple
Customer transcoding requirements are growing beyond file‐to‐file transcoding as capabilities previously only seen in non-linear editing systems become possible at transcode time. For example, it’s now possible to apply media transformation templates to incoming content to render a finished, composited, mixed output file without taking up a video editing station’s valuable time. Transcoding solution vendors need to keep up with this type of technology, as well as support for track‐based media assembly and composition, frame‐accurate video and audio mixing, and track-based video and audio effects like dissolves, cuts, and fades.
To get the greatest flexibility and scalability, a transcoding solution should do the following:
- Support a diversity of formats
- Enable multiplatform transcoding
- Support an adaptive transcoding model, in which transcoding settings can adapt to the incoming source media and inherit parameters such as frame rate, audio sample rate, audio bitrate, etc.
- Support transwrapping, in which video essence data (the raw, compressed video data inside a container such as MXF or MOV) can be passed through the transcoding process without re-encoding. Transwrapping provides much faster performance in situations where you want to process audio data, such as for loudness correction or upmixing from stereo to multichannel audio, or where closed-caption data is being inserted.
More importantly, transcoding settings should be able to adapt to the incoming aspect ratio, and assign frame size and crop region to the transcoding engine based on the incoming media source. For example, you should be able to develop a single transcode setting which generates a 400×300 H.264 output file from content with a 4:3 aspect ratio, but which also generates a 400×226 H.264 output file from content with a 16:9 aspect ratio.
Or, if you know that all 4:3 content will be letterboxed, you should be able to set the transcoding to automatically assign a crop region to 4:3 content to strip off letterboxing, generate 16:9 output, and pass through 16:9 sources without cropping. This makes for an efficient, templated transcoding model because the same settings can be used for a wider range of incoming source media.
Transcoding has typically been a file‐in, file‐out workflow in which transcoding jobs are distributed around the transcoding farm as capacity becomes available. This architecture works well for bulk transcoding where the amount of content saturates the transcoding farm and you have 100% utilization of your resources.
If you have content that requires an immediate turnaround (e.g., breaking news stories, late edits to on‐air content), you can use RadiantGrid Technologies’ TrueGrid™ transcoding, which transcodes source content in parallel across all your available transcoding resources. This process distributes virtual slices of the source content across all available resources, and once these slices have been transcoded, they are reassembled to generate the final transcoded file.
Read more about RadiantGrid’s transcoding platform and their plug-in to thePlatform Remote Media Processor (RMP).
Kirk Marple is President and Chief Software Architect of RadiantGrid Technologies.
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