public RawImage rawimage;


 void Start () {

     WebCamDevice backCameraDevice;
     Debug.Log("code started");
     WebCamDevice[] devices = WebCamTexture.devices;
     for (int i = 0; i < devices.Length; i++)
         Debug.Log(devices[i].name);

     if (WebCamTexture.devices.Length == 0)
     {
         Debug.Log("No devices cameras found");
         return;
     }

     backCameraDevice = WebCamTexture.devices[0];
     Debug.Log(backCameraDevice.name);

     WebCamTexture webcamTexture = new  WebCamTexture(backCameraDevice.name);
     webcamTexture.requestedWidth = 150;
     webcamTexture.requestedHeight = 150;

     rawimage.texture = webcamTexture;

     rawimage.material.mainTexture = webcamTexture;
     webcamTexture.Play();

 }