time of emitting the first.
*/
- list<dcp::SubtitleString> s;
- list<dcp::SubtitleImage> i;
+ vector<dcp::SubtitleString> s;
+ vector<dcp::SubtitleImage> i;
auto const p = content_time_period (*_next);
while (_next != _subtitles.end () && content_time_period (*_next) == p) {