test struct.unpack rather than class

Author: zm711

neo/rawio/micromedrawio.py

@@ -146,8 +146,13 @@ def _parse_header(self):
                 gain = factor
                 offset = -logical_ground * factor
 
-                f.seek(8, 1)
-                (sampling_rate,) = f.read_f("H")
+                # this skips the filtering info done with the machine
+                f.seek(8, 1) 
+                
+                #(sampling_rate,) = f.read_f("H")
+                # sampling_rate is actually the rate_coefficient which is multipled by the 
+                # Rate_Min which is the sampling_rate
+                sampling_rate = struct.unpack("H", f.read(struct.calcsize("H")))
                 sampling_rate *= Rate_Min
                 chan_id = str(c)
                 signal_channels.append(