if (signals_.size() == 0)
return make_pair(0, 0);
- data.push_back(signals_.front()->data());
+ for (shared_ptr<Signal> s : signals_)
+ if (s->data()->segments().size() > 0)
+ data.push_back(s->data());
for (const shared_ptr<SignalData>& d : data) {
const vector< shared_ptr<Segment> > segments = d->segments();