Update, I try a new code with advice of this topic :

2. import ketai.camera.*;
3. 
   
4. KetaiCamera video;
5. 
   
6. void setup() {
7.   orientation(PORTRAIT);
8.   size(640, 480, P2D);
9.   video = new KetaiCamera(this, 640, 480, 15);
10.   video.setCameraID(0);
11. }
12. 
    
13. void draw() {
14.   image(video, width/2, height/2);
15. }
16. 
    
17. void onPause() {
18.   super.onPause();
19.   if (video != null&& video.isStarted()) {
20.     video.stop();
21.   }
22. }
23. 
    
24. void onCameraPreview() {
25. 
    
26.   video.read();
27. }
28. void exit() {
29.   video.stop();
30. }
31. 
    
32. void mousePressed()
33. {
34.   if (video.isStarted())
35.   {
36.     video.stop();
37.   }
38.   else
39.     video.start();
40. }

So the program run, but it doesn't show camera on image();

I just got a white screen……

But good news, the console show information about the camera, about run and stop. 

But I got a new problem about video/camera : the preview crashes after couple of frames.

This my code :

2. import ketai.camera.*;
3. 
   
4. capta_video cV;
5. 
   
6. KetaiCamera video;
7. void setup() {
8. 
   
9.   orientation(PORTRAIT);
10. 
    
11.   size(displayWidth, displayHeight, P3D);
12. 
    
13.   background(0);
14. 
    
15.   video = new KetaiCamera(this, 320, 240, 15); 
16.   video.setCameraID(0);
17. }
18. 
    
19. void draw() {
20. 
    
21.   cV = new capta_video(600, 100);
22. }
23. void onPause() {
24.   super.onPause();
25.   if (video != null&& video.isStarted()) {
26.     video.stop();
27.   }
28. }
29. 
    
30. void onCameraPreviewEvent() {
31. 
    
32.   video.read();
33. }
34. void exit() {
35.   video.stop();
36. }
37. 
    
38. void mousePressed()
39. {
40.   if (video.isStarted())
41.   {
42.     video.stop();
43.   }
44.   else
45.     video.start();
46. }

and the class :

2. class capta_video {
3.   int posX, posY;
4.   int blockSize = 1;
5.   color [] colorV;
6.   int numPixelsWide, numPixelsHigh;
7. 
   
8.   capta_video(int _posX, int _posY) {
9. 
   
10.     posX= _posX;
11.     posY= _posY;
12.     numPixelsWide = width / blockSize;
13.     numPixelsHigh = height / blockSize;
14. 
    
15.     colorV  = new color [numPixelsWide * numPixelsHigh];
16.     pushMatrix();
17.     translate(posX, posY);
18.     rectMode(CORNER);
19.     imageMode(CORNER);
20.     rotateZ(radians(90));
21.     fill(255, 0, 0);
22.     rect(0, 0, 40, 40);
23.     image(video, 0, 0);
24. 
    
25.     //video.loadPixels();
26.     int pixelColor;
27.     int count = 0;
28.     for (int j = 0; j < 1; j++) {
29.       for (int i = 0; i < numPixelsWide; i++) {
30.         colorV[count] = video.get(i*blockSize, j*blockSize);
31.         count++;
32.       }
33.     }
34. 
    
35.     for (int j = 0; j < 1; j++) {
36.       for (int i = 0; i < numPixelsWide; i++) {
37.         noStroke();
38.         fill(colorV[j*numPixelsWide + i]);
39.         rect(i*blockSize, j*blockSize - 100, blockSize, blockSize);
40.       }
41.     }
42. 
    
43.     popMatrix();
44.   }
45. }

and the console :