int const amount = min (in->frames(), _tail->frames());
if (amount < _tail->frames ()) {
_tail->move (amount, 0, _tail->frames() - amount);
}
_tail->copy_from (in.get(), amount, in->frames() - amount, _tail->frames () - amount);
int const amount = min (in->frames(), _tail->frames());
if (amount < _tail->frames ()) {
_tail->move (amount, 0, _tail->frames() - amount);
}
_tail->copy_from (in.get(), amount, in->frames() - amount, _tail->frames () - amount);