diff --git a/saleae_usb_pcap.py b/saleae_usb_pcap.py
line changes: +20/-10
index 04ed87d..1c2d86c
--- a/saleae_usb_pcap.py
+++ b/saleae_usb_pcap.py

@@ -229,13 +229,14 @@ class UsbPacketCombo(Enum):
 
 class UsbPacketBuffer(object):
     """Buffer of decoded UsbPackets that haven't been written to disk yet."""
-    def __init__(self, pcap, max_fold=64):
+    def __init__(self, pcap, max_fold=64, fold_over_sof=False):
         self.buffer = []
         self.max_fold = max_fold
         self.written = 0
         self.seen = 0
         self.pcap = pcap
         self.last_timestamp = 0
+        self.fold_over_sof = fold_over_sof
 
     def add(self, pkt):
         self.buffer.append(pkt)

@@ -244,16 +245,25 @@ class UsbPacketBuffer(object):
         self.write(flush=True)
 
     def fold(self, data, combo, pkt_count, buffer):
-        count = 0
         if combo == UsbPacketCombo.UNKNOWN:
             return 0
-        # check units of pkt_count for the same combo
-        for i in range(0, len(buffer), pkt_count):
+
+        # scan for the same packet combo, counting how many packets in
+        # a row can be skipped
+        i = 0
+        while i < len(buffer):
             next_combo, next_count, next_data = UsbPacketCombo.find(buffer[i:i+pkt_count])
-            if next_combo != combo or next_count != pkt_count or next_data != data:
-                break
-            count += 1
-        return count*pkt_count
+            if self.fold_over_sof:
+                # ignore SOF packets when folding
+                if next_combo != UsbPacketCombo.SOF and \
+                   (next_combo != combo or next_count != pkt_count or next_data != data):
+                    break
+            else:
+                # stop folding on SOFs
+                if next_combo != combo or next_count != pkt_count or next_data != data:
+                    break
+            i += next_count
+        return i
 
     def write(self, flush=False):
         # only consume packets down to the maximum folding level,

@@ -297,7 +307,7 @@ def events_from_csv(csvfile):
             events.append(event)
     return events
 
-def csv_to_pcap(csvfile, pcapfile, unfolded=False):
+def csv_to_pcap(csvfile, pcapfile, unfolded=False, fold_over_sof=False, fold_max=1024):
     # parse saleae CSV file into event objects
     events = events_from_csv(csvfile)
 

@@ -308,7 +318,7 @@ def csv_to_pcap(csvfile, pcapfile, unfolded=False):
     pcap.write_info_header()
 
     # initialize a buffer for processing packet combinations
-    buffer = UsbPacketBuffer(pcap, max_fold=0 if unfolded else 128)
+    buffer = UsbPacketBuffer(pcap, max_fold=0 if unfolded else fold_max, fold_over_sof=fold_over_sof)
 
     packet = None
     for event in events: