bool mltRemoveClip(int track, GenTime position);
bool mltRemoveEffect(int track, GenTime position, QString index, bool doRefresh = true);
bool mltAddEffect(int track, GenTime position, QHash <QString, QString> args, bool doRefresh = true);
bool mltRemoveClip(int track, GenTime position);
bool mltRemoveEffect(int track, GenTime position, QString index, bool doRefresh = true);
bool mltAddEffect(int track, GenTime position, QHash <QString, QString> args, bool doRefresh = true);