func:  nestegg_track_default_duration(nestegg * ctx, unsigned int uint64_t * duration) struct track_entry * entry ; uint64_t value ; entry = ne_find_track_entry ( ctx , track ); static struct track_entry ne_find_track_entry(nestegg * ctx, unsigned int track) struct ebml_list_node * node ; unsigned int tracks = 0 ; node = ctx -> segment . tracks . track_entry . head; while ( node )  if ( track == tracks )  return node -> data ; tracks += 1; node = node -> next; return NULL ; if ( ! entry )  if ( ne_get_uint ( entry -> default_duration , & value ) != 0 )  static ne_get_uint(struct ebml_type type, uint64_t * value) if ( ! type . read )  assert ( type . type == TYPE_UINT ); 