修复四个关键bug: dest_fps限速/底行越界/255应为-1/删除debug文件重载

src/image_cv.cpp

@@ -261,7 +261,8 @@ void image_main()
     }
 
     // ── 6. 中线计算 + 丢线补全 ─────
-    for (int row = line_tracking_height - 1; row >= 10; --row)
+    // 从倒数第二行开始向上，底行(row=height-1)单独兜底避免 mid_line[row+1] 越界
+    for (int row = line_tracking_height - 2; row >= 10; --row)
     {
         // ── 6a. 丢线补全 ──────────────────────────────
         if (left_line[row] == -1 && right_line[row] == -1)
@@ -290,4 +291,18 @@ void image_main()
             mid_line[row] = (left_line[row] + right_line[row]) / 2;
         }
     }
+    // 底行兜底：正常计算，丢线时用图像中心
+    {
+        const int row = line_tracking_height - 1;
+        if (left_line[row] == -1 && right_line[row] == -1)
+        {
+            mid_line[row] = line_tracking_width / 2;
+            left_line[row]  = 0;
+            right_line[row] = line_tracking_width - 1;
+        }
+        else
+        {
+            mid_line[row] = (left_line[row] + right_line[row]) / 2;
+        }
+    }
 }