Large update of videoio doc and samples following mshabunin comments

samples/cpp/videocapture_basic.cpp

@@ -0,0 +1,52 @@
+/**
+  @file videocapture_basic.cpp
+  @brief A very basic sample for using VideoCapture and VideoWriter
+  @author PkLab.net
+  @date Aug 24, 2016
+*/
+
+#include <opencv2/opencv.hpp>
+#include <iostream>
+#include <stdio.h>
+
+using namespace cv;
+using namespace std;
+
+int main(int, char**)
+{
+    Mat frame;
+    //--- INITIALIZE VIDEOCAPTURE
+    VideoCapture cap;
+    // open the default camera using default API
+    cap.open(0);
+    // OR advance usage: select any API backend
+    int deviceID = 0;             // 0 = open default camera
+    int apiID = cv::CAP_ANY;      // 0 = autodetect default API
+    // open selected camera using selected API
+    cap.open(deviceID + apiID);
+    // check if we succeeded
+    if (!cap.isOpened()) {
+        cerr << "ERROR! Unable to open camera\n";
+        return -1;
+    }
+
+    //--- GRAB AND WRITE LOOP
+    cout << "Start grabbing" << endl
+        << "Press any key to terminate" << endl;
+    for (;;)
+    {
+        // wait for a new frame from camera and store it into 'frame'
+        cap.read(frame);
+        // check if we succeeded
+        if (frame.empty()) {
+            cerr << "ERROR! blank frame grabbed\n";
+            break;
+        }
+        // show live and wait for a key with timeout long enough to show images
+        imshow("Live", frame);
+        if (waitKey(5) >= 0)
+            break;
+    }
+    // the camera will be deinitialized automatically in VideoCapture destructor
+    return 0;
+}

samples/cpp/videocapture_starter.cpp

@@ -1,14 +1,13 @@
-/*
-* starter_video.cpp
+/**
+* @file videocapture_starter.cpp
+* @brief A starter sample for using OpenCV VideoCapture with capture devices, video files or image sequences
+* easy as CV_PI right?
 *
 *  Created on: Nov 23, 2010
 *      Author: Ethan Rublee
 *
 *  Modified on: April 17, 2013
 *      Author: Kevin Hughes
-*
-* A starter sample for using OpenCV VideoCapture with capture devices, video files or image sequences
-* easy as CV_PI right?
 */
 
 #include <opencv2/imgcodecs.hpp>

samples/cpp/videowriter_basic.cpp

@@ -0,0 +1,65 @@
+/**
+  @file videowriter_basic.cpp
+  @brief A very basic sample for using VideoWriter and VideoCapture
+  @author PkLab.net
+  @date Aug 24, 2016
+*/
+
+#include <opencv2/opencv.hpp>
+#include <iostream>
+#include <stdio.h>
+
+using namespace cv;
+using namespace std;
+
+int main(int, char**)
+{
+    Mat src;
+    // use default camera as video source
+    VideoCapture cap(0);
+    // check if we succeeded
+    if (!cap.isOpened()) {
+        cerr << "ERROR! Unable to open camera\n";
+        return -1;
+    }
+    // get one frame from camera to know frame size and type
+    cap >> src;
+    // check if we succeeded
+    if (src.empty()) {
+        cerr << "ERROR! blank frame grabbed\n";
+        return -1;
+    }
+    bool isColor = (src.type() == CV_8UC3);
+
+    //--- INITIALIZE VIDEOWRITER
+    VideoWriter writer;
+    int codec = CV_FOURCC('M', 'J', 'P', 'G');  // select desired codec (must be available at runtime)
+    double fps = 25.0;                          // framerate of the created video stream
+    string filename = "./live.avi";             // name of the output video file
+    writer.open(filename, codec, fps, src.size(), isColor);
+    // check if we succeeded
+    if (!writer.isOpened()) {
+        cerr << "Could not open the output video file for write\n";
+        return -1;
+    }
+
+    //--- GRAB AND WRITE LOOP
+    cout << "Writing videofile: " << filename << endl
+         << "Press any key to terminate" << endl;
+    for (;;)
+    {
+        // check if we succeeded
+        if (!cap.read(src)) {
+            cerr << "ERROR! blank frame grabbed\n";
+            break;
+        }
+        // encode the frame into the videofile stream
+        writer.write(src);
+        // show live and wait for a key with timeout long enough to show images
+        imshow("Live", src);
+        if (waitKey(5) >= 0)
+            break;
+    }
+    // the videofile will be closed and released automatically in VideoWriter destructor
+    return 0;
+}