In the HLS Spec (https://tools.ietf.org/html/draft-pantos-hls-rfc8216bis-04#section-4.4.3.6), specifically this or condition of this statement:
"... defined by the EXT-X-MAP tag, or is located between the start of the resource
and the offset of the first I-frame segment in that resource."
Change adds code to add this "implicit" Media Initialization Segment if no EXT-X-MAP defines one explicitly.
