diff --git a/sf-buffer/src/sf_replay.cpp b/sf-buffer/src/sf_replay.cpp
index c0d8acd..5bb9484 100644
--- a/sf-buffer/src/sf_replay.cpp
+++ b/sf-buffer/src/sf_replay.cpp
@@ -124,7 +124,10 @@ int main (int argc, char *argv[]) {
                      512 * 1024 * 2,
                      0);
 
-            zmq_recv(meta_socket, nullptr, 0, 0);
+            if ((i_frame > 0) && (i_frame%50 == 0)) {
+                // Wait for the sync message.
+                zmq_recv(meta_socket, nullptr, 0, 0);
+            }
         }
     }
 
diff --git a/sf-writer/sf_h5_writer.cpp b/sf-writer/sf_h5_writer.cpp
index f3ba308..b84d85c 100644
--- a/sf-writer/sf_h5_writer.cpp
+++ b/sf-writer/sf_h5_writer.cpp
@@ -61,6 +61,8 @@ int main (int argc, char *argv[])
     auto image_buffer = make_unique<uint16_t[]>(512 * 1024);
     unordered_map<uint64_t, int> received_counter;
 
+    size_t n_recv_modules = 0;
+
     while (true) {
         auto n_bytes_metadata = zmq_recv(
                 socket,
@@ -91,13 +93,16 @@ int main (int argc, char *argv[])
 
             if (received_counter[metadata_buffer->pulse_id] == 0) {
                 received_counter.erase(metadata_buffer->pulse_id);
+                n_recv_modules++;
             }
         }
 
         size_t n_in_progress_frames = received_counter.size();
-        cout << "n frames in progress " << n_in_progress_frames << endl;
-        if (n_in_progress_frames == 0) {
+        cout << "n frames in progress " << n_in_progress_frames;
+        cout << "n_recv_modules " << n_recv_modules << endl;
+        if (n_recv_modules == 32) {
             zmq_send(meta_socket, "", strlen(""), 0);
+            n_recv_modules = 0;
         }
     }