diff --git a/README.md b/README.md
index f0835cd..53a5e56 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
-* Subscribe to a ZMQ pub socket with `record_sub.py`
-* Playback the recorded messages by publishing them to the provided port with `record_playback.py`
-	* Messages should be played with the same timing offsets as they were recorded. Starting after the first message.
+* Subscribe to a ZMQ pub socket with `uv run record_sub.py`
+	* Provide port and filename as arguments. For example: `uv run record_sub.py 99174 messages-20250701.jsonl`
+* Playback the recorded messages by publishing them to the provided port with `uv run record_playback.py`
+	* Messages should be played with the same timing offsets as they were recorded. Starting after the first message (which is send immediately, without delay).
+	* Again, provide port and filename as arguments: `uv run record_playback.py 99174 messages-20250701.jsonl `
 
 Usefull for testing the functionality of a pubsub subsciber script.
diff --git a/record_playback.py b/record_playback.py
index e85b7d8..ba64e89 100644
--- a/record_playback.py
+++ b/record_playback.py
@@ -6,7 +6,7 @@ import sys
 import time
 import json
 
-port = "99173"
+port = "99174"
 if len(sys.argv) > 1:
     port =  sys.argv[1]
     int(port)
diff --git a/record_sub.py b/record_sub.py
index a2bf9f0..2885086 100644
--- a/record_sub.py
+++ b/record_sub.py
@@ -4,6 +4,7 @@ Record messages
 
 from dataclasses import dataclass
 from typing import Any
+import tqdm
 import zmq
 import random
 import sys
@@ -11,11 +12,22 @@ import time
 import json
 import jsonlines
 
+port = "99174"
+if len(sys.argv) > 1:
+    port =  sys.argv[1]
+    int(port)
+
+if len(sys.argv) > 2:
+    fn = sys.argv[2]
+else:
+    fn = "messages.jsonl"
 
 context = zmq.Context()
 socket = context.socket(zmq.SUB)
 
-socket.connect ("tcp://100.109.175.82:99173")
+addr = f"tcp://100.109.175.82:{port}"
+
+socket.connect (addr)
 socket.setsockopt_string(zmq.SUBSCRIBE, "")
 #print('connected')
 # Subscribe to zipcode, default is NYC, 10001
@@ -24,18 +36,21 @@ socket.setsockopt_string(zmq.SUBSCRIBE, "")
 
 last = time.time()
 
-with jsonlines.open('messages.jsonl', mode='w', flush=True) as writer:
-    while True:
-        string = socket.recv_string()
-        data = json.loads(string)        
-        now = time.time()
-        msg = {
-            'data': data,
-            'offset': now - last
-        }
-        print(msg['offset'])
-        writer.write(msg)
-        last = now
+print(f"Listen to {addr}, write to {fn}")
+
+with jsonlines.open(fn, mode='w', flush=True) as writer:
+    with tqdm.tqdm() as pbar:
+        while True:
+            pbar.update()
+            string = socket.recv_string()
+            data = json.loads(string)        
+            now = time.time()
+            msg = {
+                'data': data,
+                'offset': now - last
+            }
+            writer.write(msg)
+            last = now
         
     #topic, messagedata = string.split()
     #total_value += int(messagedata)