diff --git a/client/webrtc_capture/src/camera_video_sink.cpp b/client/webrtc_capture/src/camera_video_sink.cpp
index cd55558..2dc19df 100644
--- a/client/webrtc_capture/src/camera_video_sink.cpp
+++ b/client/webrtc_capture/src/camera_video_sink.cpp
@@ -82,10 +82,14 @@ void CameraVideoSink::OnFrame(const webrtc::VideoFrame& frame) {
     cnt++;
     int width = this->m_capability.width;
     int height = this->m_capability.height;
-    qDebug()<<this->Capability().height<<this->Capability().width
-           <<int(this->Capability().videoType)
+    webrtc::VideoCaptureCapability cap;
+    int ret = this->Capability(cap);
+    if(ret < 0)
+        return ;
+    qDebug()<<cap.height<<cap.width
+           <<int(cap.videoType)
           <<int(webrtc::VideoType::kI420)
-         <<this->Capability().interlaced<<width * height*4;
+         <<cap.interlaced<<width * height*4;
 
     uint8_t *data =
             new uint8_t[width * height*4];
@@ -108,9 +112,13 @@ void CameraVideoSink::OnFrame(const webrtc::VideoFrame& frame) {
 }
 
 
-webrtc::VideoCaptureCapability CameraVideoSink::Capability()
+int CameraVideoSink::Capability(webrtc::VideoCaptureCapability &cap)
 {
-    return this->m_capability;
+    if(nullptr != this)
+        cap = this->m_capability;
+    else
+        return -1;
+    return 0;
 }
 
 uint8_t *FrameBufferList::TakeLast()
diff --git a/client/webrtc_capture/src/camera_video_sink.h b/client/webrtc_capture/src/camera_video_sink.h
index 4eb512f..8195902 100644
--- a/client/webrtc_capture/src/camera_video_sink.h
+++ b/client/webrtc_capture/src/camera_video_sink.h
@@ -33,7 +33,7 @@ public:
                                  size_t capture_device_index);
     virtual ~CameraVideoSink();
     void OnFrame(const webrtc::VideoFrame& frame) override;
-    webrtc::VideoCaptureCapability Capability();
+    int Capability(webrtc::VideoCaptureCapability &cap);
     FrameBufferList *VideoBuffer(){
         return &this->m_buf;
     }
diff --git a/client/webrtc_capture/src/mainwindow.cpp b/client/webrtc_capture/src/mainwindow.cpp
index 13f4d29..7c0123d 100644
--- a/client/webrtc_capture/src/mainwindow.cpp
+++ b/client/webrtc_capture/src/mainwindow.cpp
@@ -87,9 +87,13 @@ void MainWindow::on_pushButton_clicked()
     if (!m_capturer) {
         qDebug()<<"error";
     }
+    webrtc::VideoCaptureCapability cap;
+    int ret = m_capturer->Capability(cap);
+    if(ret < 0)
+        return;
     ui->openGLWidget->SetDataType(CPlayWidget::TYPE_YUV420P);
-    ui->openGLWidget->SetImgSize(m_capturer->Capability().width,
-                                 m_capturer->Capability().height);
+    ui->openGLWidget->SetImgSize(cap.width,
+                                 cap.height);
     ui->openGLWidget->StartRender();
 //    ui->openGLWidget->moveToThread(&gRender->Thread());
     if(gRender == nullptr){