WIP - compatibility with net station

Author: cboulay

README.md

@@ -3,6 +3,7 @@
 ## Usage
 
 This program should work with any amplifier that works with the AmpServer produced by EGI (http://www.egi.com/).
+All communication with the amplifier happens through the Amp Server Pro SDK, [documented here](https://www.egi.com/images/stories/manuals/amp-server-pro-sdk-3-0-network-apis-user-guide-rev-01.pdf).
 
   * Make sure that your AmpServer is running and can correctly record from its connected amplifier(s). To connect to the Amp Server you need to purchase the Amp Server Pro SDK, see: [ftp://ftp.egi.com/pub/documentation/placards/AS_guide_8409503-50_20100421.pdf](ftp://ftp.egi.com/pub/documentation/placards/AS_guide_8409503-50_20100421.pdf), otherwise the LSL application will not work.
 
@@ -44,3 +45,27 @@ To use the mock server for development:
 > # or update ampserver_config.cfg to use 127.0.0.1 and run GUI
 
 The mock server generates synthetic sine waves (10-50 Hz) with noise for the EEG data, so you can also verify the LSL stream in downstream applications.
+
+# Known Issues
+
+## Net Station Acquisition Compatibility
+
+When using this application alongside Net Station Acquisition:
+
+- **Start Net Station first**: If you plan to use Net Station Acquisition, start it and initialize the amplifier (click "On") BEFORE connecting this app. Our app will detect the running amplifier and automatically use its sample rate.
+
+- **Do not start Net Station after**: If this app is already streaming and Net Station subsequently initializes the amplifier at a different sample rate, our app cannot detect this change. AmpServer only sends notifications to one subscriber, and Net Station consumes them when it's running.
+
+- **Recommended workflow**:
+  1. Start Net Station Acquisition
+  2. Initialize the amplifier at your desired sample rate (click "On")
+  3. Start EGIAmpServer and click "Link" - it will detect the running amp and match its sample rate
+  4. Both applications will now receive data at the correct rate
+
+## Dropped Packets After Device Shutdown
+
+After Net Station shuts down the amplifier (via "Shutdown" command), immediately starting this app may result in excessive dropped packets and eventual stream loss. This appears to be related to stale data in the connection. **Workaround**: Wait a moment and restart the app, or power cycle the amplifier.
+
+## Sample Rate Auto-Detection
+
+The app automatically detects the sample rate when connecting to an already-running amplifier by measuring packet timing. This detection snaps to standard rates (250, 500, or 1000 Hz). If the amplifier is idle when connecting, the app uses the sample rate configured in the UI/config file.

src/cli/main.cpp

@@ -31,7 +31,6 @@ void printUsage(const char* programName) {
               << "  --data-port <port> Data port (default: 9879)\n"
               << "  --amp-id <id>      Amplifier ID (default: 0)\n"
               << "  --sample-rate <hz> Sample rate (default: 1000)\n"
-              << "  --listen-only      Don't initialize amp, just listen (for multi-client)\n"
               << "  --help             Show this help message\n";
 }
 
@@ -58,8 +57,6 @@ int main(int argc, char* argv[]) {
             config.amplifierId = std::stoi(argv[++i]);
         } else if (arg == "--sample-rate" && i + 1 < argc) {
             config.sampleRate = std::stoi(argv[++i]);
-        } else if (arg == "--listen-only") {
-            config.listenOnly = true;
         } else {
             std::cerr << "Unknown option: " << arg << std::endl;
             printUsage(argv[0]);
@@ -108,7 +105,6 @@ int main(int argc, char* argv[]) {
               << "  Data Port: " << config.dataPort << "\n"
               << "  Amplifier ID: " << config.amplifierId << "\n"
               << "  Sample Rate: " << config.sampleRate << " Hz\n"
-              << "  Listen Only: " << (config.listenOnly ? "yes" : "no") << "\n"
               << "Press Ctrl+C to stop.\n\n";
 
     // Connect and stream

src/core/include/egiamp/AmpServerConfig.h

@@ -15,10 +15,6 @@ struct AmpServerConfig {
     int amplifierId = 0;
     int sampleRate = 1000;
 
-    // If true, just listen to an already-running amp without initializing it.
-    // This allows multiple clients to connect without disrupting each other.
-    bool listenOnly = false;
-
     static AmpServerConfig loadFromFile(const std::string& filename);
     void saveToFile(const std::string& filename) const;
 };

src/core/include/egiamp/AmpServerConnection.h

@@ -26,6 +26,9 @@ class AmpServerConnection {
     void disconnect();
     bool isConnected() const;
 
+    // Reconnect just the data stream (used to reset stream position after detection)
+    bool reconnectDataStream();
+
     std::string sendCommand(const std::string& command, int ampId,
                             int channel = 0, const std::string& value = "0");
     void sendDatastreamCommand(const std::string& command, int ampId,
@@ -50,6 +53,8 @@ class AmpServerConnection {
     socket_stream notificationStream_;
     socket_stream dataStream_;
     std::atomic<bool> connected_{false};
+    std::string serverAddress_;
+    uint16_t dataPort_{0};
 };
 
 } // namespace egiamp

src/core/include/egiamp/EGIAmpClient.h

@@ -46,6 +46,11 @@ class EGIAmpClient {
     bool startStreaming();
     void stopStreaming();
 
+    // Query amp state - returns true if amp is already running, updates detectedSampleRate
+    bool queryAmpState();
+    int detectedSampleRate() const { return detectedSampleRate_; }
+    bool ampWasRunning() const { return ampWasRunning_; }
+
     const AmplifierDetails& amplifierDetails() const { return details_; }
 
     void setStatusCallback(StatusCallback cb) { statusCallback_ = std::move(cb); }
@@ -60,6 +65,8 @@ class EGIAmpClient {
     void emitChannelCount(int count);
 
     bool queryAmplifierDetails();
+    bool isAmplifierStreaming();
+    int detectSampleRate();  // Returns detected sample rate, or 0 if detection failed
     bool initAmplifier();
     void haltAmplifier();
 
@@ -73,6 +80,10 @@ class EGIAmpClient {
     AmplifierDetails details_;
 
     std::atomic<bool> stopFlag_{false};
+    std::atomic<bool> sampleRateChangeDetected_{false};  // Set when ntn_AmpStarted received
+    bool weInitializedAmp_{false};  // Track if we initialized the amp (vs. it was already running)
+    bool ampWasRunning_{false};     // Was the amp running when we queried state?
+    int detectedSampleRate_{0};     // Sample rate detected from running amp
     std::unique_ptr<std::thread> readerThread_;
     std::unique_ptr<std::thread> notificationThread_;
 

src/core/src/AmpServerConfig.cpp

@@ -40,9 +40,6 @@ AmpServerConfig AmpServerConfig::loadFromFile(const std::string& filename) {
         if (auto node = settings.child("samplingrate")) {
             config.sampleRate = node.text().as_int(config.sampleRate);
         }
-        if (auto node = settings.child("listenonly")) {
-            config.listenOnly = node.text().as_bool(config.listenOnly);
-        }
     }
 
     return config;
@@ -62,7 +59,6 @@ void AmpServerConfig::saveToFile(const std::string& filename) const {
     auto settings = doc.append_child("settings");
     settings.append_child("amplifierid").text().set(amplifierId);
     settings.append_child("samplingrate").text().set(sampleRate);
-    settings.append_child("listenonly").text().set(listenOnly);
 
     if (!doc.save_file(filename.c_str())) {
         throw ConfigError("Could not write to config file: " + filename);

src/core/src/AmpServerConnection.cpp

@@ -11,6 +11,10 @@ AmpServerConnection::~AmpServerConnection() {
 bool AmpServerConnection::connect(const std::string& address, uint16_t cmdPort,
                                   uint16_t notifyPort, uint16_t dataPort) {
     try {
+        // Store for potential reconnection
+        serverAddress_ = address;
+        dataPort_ = dataPort;
+
         // Connect command stream
         commandStream_.clear();
         commandStream_.exceptions(std::ios::eofbit | std::ios::failbit | std::ios::badbit);
@@ -36,6 +40,18 @@ bool AmpServerConnection::connect(const std::string& address, uint16_t cmdPort,
     }
 }
 
+bool AmpServerConnection::reconnectDataStream() {
+    try {
+        dataStream_.close();
+        dataStream_.clear();
+        dataStream_.expires_after(std::chrono::seconds(5));
+        dataStream_.connect(serverAddress_, std::to_string(dataPort_));
+        return true;
+    } catch (...) {
+        return false;
+    }
+}
+
 void AmpServerConnection::disconnect() {
     connected_ = false;
     commandStream_.close();