I would like to have a video running in the background which is not seen at the start of the sketch but is slowly appearing as an ellipse is moved through the screen. I can do it with an image using a blend():
Code:

  PImage a;
  
  float xpos, ypos, pxpos, pypos;
  
// lets user control DisplayItems properties, value output and drawing attributes

void setup(){
  a = loadImage("DSC00617.JPG");
  background(0);
  // set size and framerate
  frameRate(10);
 
  size(1580, 1050);
}

void draw(){
  xpos = mouseX;
  ypos = mouseY;
  noStroke();
   ellipse(xpos, ypos, 50, 50);
   blend(a, 0,0,width,height,0,0,width,height, DARKEST);
   
}
 

But when I use a video instead I get all the images of the video superimposed on top of one another:
Code:

import processing.video.*;
  Movie myMovie;
  PImage a;
  
  float xpos, ypos, pxpos, pypos;
  
// lets user control DisplayItems properties, value output and drawing attributes

void setup(){
 
  background(0);
  // set size and framerate
  frameRate(10);
 
  size(640, 480, P2D);

  myMovie = new Movie(this, "station.mov");
  myMovie.loop();
}
void movieEvent(Movie myMovie) {
  myMovie.read();
}
void draw(){
  xpos = mouseX;
  ypos = mouseY;
  noStroke();
   ellipse(xpos, ypos, 50, 50);
   blend(myMovie, 0,0,width,height,0,0,width,height, DARKEST);
   
}
 

It is also possible to get similar effect with a copy(), but then I can do it only with squares:
Code:

import processing.video.*;
  Movie myMovie;
  // lets user control DisplayItems properties, value output and drawing attributes

void setup(){
 
  
  // set size and framerate
  frameRate(10);
 
  size(150, 150, P2D);

  myMovie = new Movie(this, "station.mov");
  myMovie.loop();
  image(myMovie,0,0) ; 
  background(0);
}
void movieEvent(Movie myMovie) {
  myMovie.read();
 
 
}
void draw(){

  copy(myMovie,mouseX, mouseY,10, 10,mouseX, mouseY,10, 10); 
}
 

How can I transform these squares into a circles?
Or modify my sketch with the blend() in order to get only one video?
Thanks!

have you tried ussing a mask?