1. A source encoder configured to encode source video as a plurality of alternative video streams packed in container files, where the container files are extensible binary markup language (EBML) files, the source encoder comprising: a processor configured via a source encoding application to ingest at least one multimedia file containing a source video; wherein the source encoding application further configures the processor to: select a portion of the source video; transcode the selected portion of the source video into a plurality of alternative portions of encoded video, where each alternative portion is encoded using a different set of encoding parameters and commences with an intra frame starting a closed Group of Pictures (GOP); write each of the alternative portions of encoded video to an element of a different EBML container file, where each element is located within an EBML container file that also includes another element that indicates the encoding parameters used to encode the alternative portion of encoded video; and add an entry to at least one index that identifies the location of the element containing one of the alternative portions of encoded video within each of the EBML container files.