0x1A45DFA3(EBML-Level 0 element), {0-32}, 0x428288(DocType element), string=matroska, 0x4287(DocTypeVersion element). The specification allows for ASCII text before the EBML header and considers the level 0 EBML header element to be the beginning of the EBML document. For now this signature is offset to 1024 bytes to allow for some ASCII text to precede the header, but to assume the EBML header of a Matroska multimedia format will begin near the beginning of the file and to mitigate against wasteful processing of large files that are not Matroska multimedia.