add buffer id in neuronexus format

Author: samuelgarcia

neo/rawio/neuronexusrawio.py

@@ -166,6 +166,7 @@ def _parse_header(self):
         # will be in stream_id = 0. In the future this will be split into sub_streams based on
         # type but for now it will be the end-users responsability for this.
         stream_id = "0"  # hard-coded see note above
+        buffer_id = "0"
         for channel_index, channel_name in enumerate(channel_info["chan_name"]):
             channel_id = channel_info["ntv_chan_name"][channel_index]
             # 'ai0' indicates analog data which is stored as microvolts
@@ -189,6 +190,7 @@ def _parse_header(self):
                     1,  # no gain
                     0,  # no offset
                     stream_id,
+                    buffer_id
                 )
             )
 
@@ -197,6 +199,9 @@ def _parse_header(self):
         stream_ids = np.unique(signal_channels["stream_id"])
         signal_streams = np.zeros(stream_ids.size, dtype=_signal_stream_dtype)
         signal_streams["id"] = [str(stream_id) for stream_id in stream_ids]
+        # One unique buffer
+        signal_streams["buffer_id"] = "0"
+
         for stream_index, stream_id in enumerate(stream_ids):
             name = stream_id_to_stream_name.get(int(stream_id), "")
             signal_streams["name"][stream_index] = name