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Depending on the chosen format type, a number of different parameters will appear. Most parameters should be self-explanatory. However, a short description of some of the key features can be found at here.
Generation
If a rendition/quality of an asset is requested but has not been generated yet, it is always automatically generated. This feature referred to as on-demand transcoding and makes it possible to ensure that renditions/qualities are only generated when needed. Thus, storage space is not wasted on saving renditions/qualities that are never used.
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