sidx has "first_offset" syntax which represents the distance in bytes from anchor point to media fragment. If present, we should adjust sidx_base_offset. https://bugzilla.gnome.org/show_bug.cgi?id=776431
sidx has "first_offset" syntax which represents the distance in bytes from anchor point to media fragment. If present, we should adjust sidx_base_offset. https://bugzilla.gnome.org/show_bug.cgi?id=776431