Function libass_sys::ass_step_sub

pub unsafe extern "C" fn ass_step_sub(
    track: *mut ASS_Track, 
    now: c_longlong, 
    movement: c_int
) -> c_longlong

\brief Calculates timeshift from now to the start of some other subtitle event, depending on movement parameter. \param track subtitle track \param now current time in milliseconds \param movement how many events to skip from the one currently displayed +2 means "the one after the next", -1 means "previous" \return timeshift in milliseconds