typedef std::vector<boost::shared_ptr<VideoContent> > VideoContentList;
typedef std::vector<boost::shared_ptr<AudioContent> > AudioContentList;
typedef std::vector<boost::shared_ptr<SubtitleContent> > SubtitleContentList;
typedef std::vector<boost::shared_ptr<VideoContent> > VideoContentList;
typedef std::vector<boost::shared_ptr<AudioContent> > AudioContentList;
typedef std::vector<boost::shared_ptr<SubtitleContent> > SubtitleContentList;