Add number of samples in motion buffer in Prb::print()

src/capture/capture_motion.cpp

@@ -126,7 +126,10 @@ void CaptureMotion::printHeader(int _depth, bool _constr_by, bool _metric, bool
     if (getStateBlockMap().size() > 0)
         printState(_metric, _state_blocks, _stream, _tabs);
 
-    _stream << _tabs << "  " << "buffer size  :  " << getBuffer().size() << std::endl;
+    _stream << _tabs << "  " << "buffer size  :  " << getBuffer().size();
+    if (getBuffer().size() > 0) _stream << " ; nbr of data samples : " << getBuffer().size() - 1;
+    _stream << std::endl;
+
     if ( _metric && ! getBuffer().empty())
     {
         _stream << _tabs << "  " << "delta preint : (" << getDeltaPreint().transpose() << ")" << std::endl;