diff --git a/README.md b/README.md
index b0409a8..3e0db9c 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,7 @@ allprojects {
 Step 2. Add the dependency  
 ```java
 dependencies { 
-	    compile 'com.github.jiangdongguo:AndroidUSBCamera:2.1.0'
+	    compile 'com.github.jiangdongguo:AndroidUSBCamera:2.1.1'
 }  
 ```
 ### 2. APIs Introduction  
@@ -30,6 +30,11 @@ dependencies {
 mUVCCameraView = (CameraViewInterface) mTextureView;
 mUVCCameraView.setCallback(mCallback);
 mCameraHelper = UVCCameraHelper.getInstance();
+// set default preview size
+ mCameraHelper.setDefaultPreviewSize(1280,720);
+// set default frame format，defalut is UVCCameraHelper.Frame_FORMAT_MPEG
+// if using mpeg can not record mp4,please try yuv
+mCameraHelper.setDefaultFrameFormat(UVCCameraHelper.FRAME_FORMAT_YUYV);	
 mCameraHelper.initUSBMonitor(this, mUVCCameraView, mDevConnectListener); 
 ```
    To be attention,mCallback is a object of interface CameraViewInterface.Callback,and it's used to be listenering surfaceView