diff --git a/aos/events/logging/logger.h b/aos/events/logging/logger.h
index f6a037b..f0f0a69 100644
--- a/aos/events/logging/logger.h
+++ b/aos/events/logging/logger.h
@@ -319,24 +319,10 @@
   // pass it in here. It must provide all the channels that the original logged
   // config did.
   //
-  // Log filenames are in the following format:
-  //
-  //   {
-  //     {log1_part0, log1_part1, ...},
-  //     {log2}
-  //   }
-  // The inner vector is a list of log file chunks which form up a log file.
-  // The outer vector is a list of log files with subsets of the messages, or
-  // messages from different nodes.
-  //
-  // If the outer vector isn't provided, it is assumed to be of size 1.
+  // The single file constructor calls SortParts internally.
   LogReader(std::string_view filename,
             const Configuration *replay_configuration = nullptr);
-  LogReader(const std::vector<std::string> &filenames,
-            const Configuration *replay_configuration = nullptr);
-  LogReader(const std::vector<std::vector<std::string>> &filenames,
-            const Configuration *replay_configuration = nullptr);
-  LogReader(const std::vector<LogFile> &log_files,
+  LogReader(std::vector<LogFile> log_files,
             const Configuration *replay_configuration = nullptr);
   ~LogReader();
 
@@ -450,7 +436,7 @@
                : logged_configuration()->nodes()->size();
   }
 
-  const std::vector<std::vector<std::string>> filenames_;
+  const std::vector<LogFile> log_files_;
 
   // This is *a* log file header used to provide the logged config.  The rest of
   // the header is likely distracting.
@@ -466,14 +452,15 @@
   // State per node.
   class State {
    public:
-    State(std::unique_ptr<ChannelMerger> channel_merger);
+    State(std::unique_ptr<TimestampMapper> timestamp_mapper);
+
+    // Connects up the timestamp mappers.
+    void AddPeer(State *peer);
 
     // Returns the timestamps, channel_index, and message from a channel.
     // update_time (will be) set to true when popping this message causes the
     // filter to change the time offset estimation function.
-    std::tuple<TimestampMerger::DeliveryTimestamp, int,
-               SizePrefixedFlatbufferVector<MessageHeader>>
-    PopOldest(bool *update_time);
+    TimestampedMessage PopOldest(bool *update_time);
 
     // Returns the monotonic time of the oldest message.
     monotonic_clock::time_point OldestMessageTime() const;
@@ -484,10 +471,12 @@
 
     // Returns the starting time for this node.
     monotonic_clock::time_point monotonic_start_time() const {
-      return channel_merger_->monotonic_start_time();
+      return timestamp_mapper_ ? timestamp_mapper_->monotonic_start_time()
+                               : monotonic_clock::min_time;
     }
     realtime_clock::time_point realtime_start_time() const {
-      return channel_merger_->realtime_start_time();
+      return timestamp_mapper_ ? timestamp_mapper_->realtime_start_time()
+                               : realtime_clock::min_time;
     }
 
     // Sets the node event loop factory for replaying into a
@@ -555,10 +544,6 @@
       return node_event_loop_factory_->monotonic_now();
     }
 
-    // Sets the node we will be merging as, and returns true if there is any
-    // data on it.
-    bool SetNode() { return channel_merger_->SetNode(event_loop_->node()); }
-
     // Sets the number of channels.
     void SetChannelCount(size_t count);
 
@@ -570,7 +555,9 @@
                     State *source_state);
 
     // Returns if we have read all the messages from all the logs.
-    bool at_end() const { return channel_merger_->at_end(); }
+    bool at_end() const {
+      return timestamp_mapper_ ? timestamp_mapper_->Front() == nullptr : true;
+    }
 
     // Unregisters everything so we can destory the event loop.
     void Deregister();
@@ -586,8 +573,7 @@
     }
 
     // Sends a buffer on the provided channel index.
-    bool Send(size_t channel_index, const void *data, size_t size,
-              const TimestampMerger::DeliveryTimestamp &delivery_timestamp);
+    bool Send(const TimestampedMessage &timestamped_message);
 
     // Returns a debug string for the channel merger.
     std::string DebugString() const {
@@ -599,22 +585,24 @@
                    << "]: " << std::get<0>(message).monotonic_event_time << " "
                    << configuration::StrippedChannelToString(
                           event_loop_->configuration()->channels()->Get(
-                              std::get<2>(message).message().channel_index()))
+                              std::get<0>(message).channel_index))
                    << "\n";
         } else if (i == 7) {
           messages << "...\n";
         }
         ++i;
       }
-      return messages.str() + channel_merger_->DebugString();
+      if (!timestamp_mapper_) {
+        return messages.str();
+      }
+      return messages.str() + timestamp_mapper_->DebugString();
     }
 
    private:
     // Log file.
-    std::unique_ptr<ChannelMerger> channel_merger_;
+    std::unique_ptr<TimestampMapper> timestamp_mapper_;
 
-    std::deque<std::tuple<TimestampMerger::DeliveryTimestamp, int,
-                          SizePrefixedFlatbufferVector<MessageHeader>,
+    std::deque<std::tuple<TimestampedMessage,
                           message_bridge::NoncausalOffsetEstimator *>>
         sorted_messages_;