diff --git a/QtScrcpy/server/server.cpp b/QtScrcpy/server/server.cpp
index b4450ee..aefb812 100644
--- a/QtScrcpy/server/server.cpp
+++ b/QtScrcpy/server/server.cpp
@@ -146,11 +146,12 @@ bool Server::execute()
     args << QString::number(m_maxSize);
     args << QString::number(m_bitRate);
     args << (m_tunnelForward ? "true" : "false");
-    if (!m_crop.isEmpty()) {
-        args << m_crop;
+    if (m_crop.isEmpty()) {
+        args << "-";
     }
 
     // adb -s P7C0218510000537 shell CLASSPATH=/data/local/tmp/scrcpy-server.jar app_process / com.genymobile.scrcpy.Server 0 8000000 false
+    // mark: crop input format: "width:height:x:y" or - for no crop, for example: "100:200:0:0"
     // 这条adb命令是阻塞运行的，m_serverProcess进程不会退出了
     m_serverProcess.execute(m_serial, args);
     return true;
diff --git a/QtScrcpy/videoform.cpp b/QtScrcpy/videoform.cpp
index 360bf66..e0fd7d3 100644
--- a/QtScrcpy/videoform.cpp
+++ b/QtScrcpy/videoform.cpp
@@ -98,7 +98,8 @@ VideoForm::VideoForm(const QString& serial, quint16 maxSize, quint32 bitRate,QWi
         // support wireless connect, example:
         //m_server->start("192.168.0.174:5555", 27183, m_maxSize, m_bitRate, "");
         // only one devices, serial can be null
-        m_server->start(m_serial, 27183, m_maxSize, m_bitRate, "");
+        // mark: crop input format: "width:height:x:y" or - for no crop, for example: "100:200:0:0"
+        m_server->start(m_serial, 27183, m_maxSize, m_bitRate, "-");
     });
 
     updateShowSize(size());
diff --git a/server/src/main/java/com/genymobile/scrcpy/Server.java b/server/src/main/java/com/genymobile/scrcpy/Server.java
index b218e83..55c011f 100644
--- a/server/src/main/java/com/genymobile/scrcpy/Server.java
+++ b/server/src/main/java/com/genymobile/scrcpy/Server.java
@@ -45,29 +45,21 @@ public final class Server {
 
     @SuppressWarnings("checkstyle:MagicNumber")
     private static Options createOptions(String... args) {
+        if (args.length != 4)
+            throw new IllegalArgumentException("Expecting 4 parameters");
+
         Options options = new Options();
-        if (args.length < 1) {
-            return options;
-        }
+
         int maxSize = Integer.parseInt(args[0]) & ~7; // multiple of 8
         options.setMaxSize(maxSize);
 
-        if (args.length < 2) {
-            return options;
-        }
         int bitRate = Integer.parseInt(args[1]);
         options.setBitRate(bitRate);
 
-        if (args.length < 3) {
-            return options;
-        }
         // use "adb forward" instead of "adb tunnel"? (so the server must listen)
         boolean tunnelForward = Boolean.parseBoolean(args[2]);
         options.setTunnelForward(tunnelForward);
 
-        if (args.length < 4) {
-            return options;
-        }
         Rect crop = parseCrop(args[3]);
         options.setCrop(crop);
 
@@ -75,7 +67,7 @@ public final class Server {
     }
 
     private static Rect parseCrop(String crop) {
-        if (crop.isEmpty()) {
+        if ("-".equals(crop)) {
             return null;
         }
         // input format: "width:height:x:y"