diff --git a/sf-replay/src/main.cpp b/sf-replay/src/main.cpp
index e7b65b7..fb04ecf 100644
--- a/sf-replay/src/main.cpp
+++ b/sf-replay/src/main.cpp
@@ -4,7 +4,7 @@
 #include <cstring>
 
 #include "buffer_config.hpp"
-#include "ReplayH5Reader.hpp"
+#include "BufferBinaryReader.hpp"
 #include "ReplayZmqSender.hpp"
 
 using namespace std;
@@ -19,12 +19,15 @@ void sf_replay (
         const uint64_t stop_pulse_id
         )
 {
-    ReplayH5Reader file_reader(device, channel_name);
+    BufferBinaryReader block_reader(device, channel_name);
 
-    // "<= stop_pulse_id" because we include the stop_pulse_id in the file.
-    for (uint64_t curr_pulse_id=start_pulse_id;
-         curr_pulse_id <= stop_pulse_id;
-         curr_pulse_id++) {
+    uint64_t start_block = start_pulse_id / BUFFER_BLOCK_SIZE;
+    uint64_t stop_block = stop_pulse_id / BUFFER_BLOCK_SIZE;
+
+    // "<= stop_block" because we include the stop_block in the transfer.
+    for (uint64_t curr_block=start_block;
+         curr_block <= stop_block;
+         curr_block++) {
 
         int slot_id;
         while((slot_id = queue.reserve()) == -1) {
@@ -35,13 +38,12 @@ void sf_replay (
         auto start_time = steady_clock::now();
 
         auto metadata = queue.get_metadata_buffer(slot_id);
-        auto buffer = queue.get_data_buffer(slot_id);
 
-        file_reader.get_buffer(curr_pulse_id, metadata, buffer);
+        block_reader.get_block(curr_block, metadata);
 
         auto end_time = steady_clock::now();
-        uint64_t read_us_duration =
-                duration_cast<microseconds>(end_time-start_time).count();
+        uint64_t read_us_duration = duration_cast<microseconds>(
+                end_time-start_time).count();
 
         queue.commit();
 
@@ -75,9 +77,8 @@ int main (int argc, char *argv[]) {
     const auto start_pulse_id = (uint64_t) atoll(argv[5]);
     const auto stop_pulse_id = (uint64_t) atoll(argv[6]);
 
-    FastQueue<BufferBinaryBlock> queue(
-            MODULE_N_BYTES * BUFFER_BLOCK_SIZE,
-            REPLAY_FASTQUEUE_N_SLOTS);
+    // 0 bytes for data since everything is in the header.
+    FastQueue<BufferBinaryBlock> queue(0, REPLAY_FASTQUEUE_N_SLOTS);
 
     thread file_read_thread(sf_replay,
                             device, channel_name, ref(queue),
@@ -103,12 +104,11 @@ int main (int argc, char *argv[]) {
                     RB_READ_RETRY_INTERVAL_MS));
         }
 
-        auto m_buffer = queue.get_metadata_buffer(slot_id);
-        auto f_buffer = queue.get_data_buffer(slot_id);
+        auto block_buffer = queue.get_metadata_buffer(slot_id);
 
         auto start_time = steady_clock::now();
 
-        sender.send(m_buffer, f_buffer);
+        sender.send(block_buffer);
 
         auto end_time = steady_clock::now();
         uint64_t send_us_duration =