From 69eba455f9f5f6a4a947d97561aa421d1c9fea70 Mon Sep 17 00:00:00 2001
From: Sam Hos <sam.hos@hva.nl>
Date: Wed, 22 Jan 2025 13:32:43 +0100
Subject: [PATCH] added image compression to thread

---
 src/C++/Driver/src/main.cpp | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/C++/Driver/src/main.cpp b/src/C++/Driver/src/main.cpp
index b9c336b..87dc3de 100644
--- a/src/C++/Driver/src/main.cpp
+++ b/src/C++/Driver/src/main.cpp
@@ -48,7 +48,7 @@ void setup()
 int main()
 {
   setup();
-  // std::thread image(CapnSend);
+  std::thread image(CapnSend);
   std::thread safety([&](){ robot.robotSafety(&message); });
   std::thread sendMqtt([&](){ sendKobukiData(robot.parser.data); });
   std::thread connectionChecker(checkKobukiConnection);
@@ -66,7 +66,7 @@ int main()
 
   sendMqtt.join();
   safety.join();
-  // image.join();
+  image.join();
 }
 
 std::mutex connectionMutex;
@@ -407,6 +407,7 @@ std::string serializeKobukiData(const TKobukiData &data)
   json += "]}";
   return json;
 }
+
 // create extra function to send the message every 100ms
 // needed it so it can be threaded
 void sendKobukiData(TKobukiData &data)
@@ -420,7 +421,8 @@ void sendKobukiData(TKobukiData &data)
 }
 
 void CapnSend() {
-    VideoCapture cap(0);
+  int COMPRESSION_LEVEL = 80;
+    VideoCapture cap(0); // Open the camera
     if (!cap.isOpened()) {
         cerr << "Error: Could not open camera" << endl;
         return;
@@ -444,14 +446,21 @@ void CapnSend() {
             }
         }
 
-        // Convert the image to a byte array
+        // Compress the image (JPEG compression with adjustable quality)
         vector<uchar> buf;
-        imencode(".jpg", frame, buf);
-        auto *enc_msg = reinterpret_cast<unsigned char *>(buf.data());
+        vector<int> compression_params;
+        compression_params.push_back(IMWRITE_JPEG_QUALITY); // Set JPEG quality
+        compression_params.push_back(COMPRESSION_LEVEL);  // Adjust the quality level (0-100, lower = more compression)
 
-        // Publish the image data
-        client.publishMessage("kobuki/cam", string(enc_msg, enc_msg + buf.size()));
-        cout << "Sent image" << endl;
+        // Encode the image into the byte buffer with the specified compression parameters
+        imencode(".jpg", frame, buf, compression_params);
+
+        // Convert the vector<uchar> buffer to a string (no casting)
+        string enc_msg(buf.begin(), buf.end());
+
+        // Publish the compressed image data (MQTT, in this case)
+        client.publishMessage("kobuki/cam", enc_msg);
+        cout << "Sent compressed image" << endl;
 
         std::this_thread::sleep_for(std::chrono::milliseconds(200)); // Send image every 200ms
     }