rem: csetup_repp->seek_position_in_seconds(csetup_repp->position_in_seconds() + seconds);
add: csetup_repp->change_position_exact(seconds); csetup_repp->seek_position(); if (csetup_repp->double_buffering() == true) csetup_repp->pserver_rep.flush();
context: void ECA_ENGINE::change_position(double seconds){  conditional_stop();  csetup_repp->seek_position_in_seconds(csetup_repp->position_in_seconds() + seconds);  conditional_start();}