livehttp: add DISCONTINUITY on playlist if we have restarted stream

If provided initial-segment-number option, signal discontinuity so
player knows to reset timestamps etc for new segments.

modules/access_output/livehttp.c

@@ -591,10 +591,11 @@ static int updateIndexAndDel( sout_access_out_t *p_access, sout_access_out_sys_t
         }
 
         if ( fprintf( fp, "#EXTM3U\n#EXT-X-TARGETDURATION:%zu\n#EXT-X-VERSION:3\n#EXT-X-ALLOW-CACHE:%s"
-                          "%s\n#EXT-X-MEDIA-SEQUENCE:%"PRIu32"\n", p_sys->i_seglen,
+                          "%s\n#EXT-X-MEDIA-SEQUENCE:%"PRIu32"\n%s", p_sys->i_seglen,
                           p_sys->b_caching ? "YES" : "NO",
                           p_sys->i_numsegs > 0 ? "" : b_isend ? "\n#EXT-X-PLAYLIST-TYPE:VOD" : "\n#EXT-X-PLAYLIST-TYPE:EVENT",
-                          i_firstseg ) < 0 )
+                          i_firstseg, ((p_sys->i_initial_segment > 1) && (p_sys->i_initial_segment == i_firstseg)) ? "#EXT-X-DISCONTINUITY\n" : ""
+                          ) < 0 )
         {
             free( psz_idxTmp );
             fclose( fp );