Processing 2.0 video alpha channel

Core Library Questions

rob.carro..

Processing 2.0 video alpha channel

in Core Library Questions • 1 year ago

HI,

This may be a stupid one but I have a video (.mov) with an alpha channel embedded and I want to overlay this onto a background image PImage (the end result is I want to overlay a live capture feed).

How can I play the overlayed video with the alpha channel??

Sorry if this is a reeally dumb question but I have looked around and cannot find any reference either in the documentation or in the GSvideo site...

Thanks for any pointers in advance..

Regards

Rob

import processing.video.*;
PImage img;
Movie myMovie;
void setup() {
size(960, 640);
img = loadImage("MovieStart.jpg");
myMovie = new Movie(this, "Mock.mov");
myMovie.play();
}
void draw() {
image(img, 0, 0);
image(myMovie, 0, 0);
}
void movieEvent(Movie m) {
m.read();
}

Replies(7)

shiffman

Re: Processing 2.0 video alpha channel

11 months ago

The video library, as far as I know, does support alpha channels. I believe this will work.

1) The movie you want to display
2) A movie with identical resolution and length that is a grayscale alpha mask (essentially movie #1's alpha channel as a separate movie).

You can then apply movie #2 as a mask to movie #1 using:

http://www.processing.org/reference/PImage_mask_.html

gimsech

Re: Processing 2.0 video alpha channel

9 months ago

Hey Daniel,

thank you for your support!

I tried this:

import processing.video.*;
Movie img, maskImg;

void setup() {
size(640,360);
background(0);
frameRate(25);
maskImg = new Movie(this, "gimsech_1.mp4");
img = new Movie(this, "gimsech_a.mp4");
img.play();
maskImg.play();
img.mask(maskImg);
}

void draw() {
image(img, 0, 0);
}

void movieEvent(Movie m) {
m.read();
}

I get this error:

mask() can only be used with an image that's the same size.

The Videos are the same size and length.
I also wanted to try this out. But it doesn't work.

Did I do something wrong or does it just don't work?

cheers
gimsech

gimsech

Processing 2.0 video alpha channel

9 months ago

What I tried now:

I tried to use the same Video twice:

maskImg = new Movie(this, "001.mp4");
img = new Movie(this, "001.mp4");
img.play();
maskImg.play();
img.mask(maskImg);

→ no luck (mask() can only be used with an image that's the same size)

I tried to use the same Movie instance:

img = new Movie(this, "001.mp4");
img.play();
img.mask(img);

→ no luck, because there wasn't a alpha channel effect. It only displayed the Video itself.

I created a *.avi File with an alpha channel inside → no luck
And I tried all this with a *.mov and a *.mp4

It worked with an *.avi an alpha channel inside, like this:

maskImg = new Movie(this, "gimsech.avi");
img = new Movie(this, "gimsech.avi");
img.play();
maskImg.play();
img.mask(maskImg);

BUT: my video is now upside down...
and it is huge! neraly 3 GB for only 1,5 Minutes!

I'm working with Processing 2.0b7.

akiersky

Re: Processing 2.0 video alpha channel

9 months ago

hi rob,

I have done this before with an Animation compressed .mov file. the filesize gets pretty beastly but it does support the alpha channel. I posted this class on this other forum thread, it should do what you need:

https://forum.processing.org/topic/gsvideo-with-alpha-channel

import processing.opengl.*;
import codeanticode.gsvideo.*;
import codeanticode.glgraphics.*;
public class BGvideo {
GSMovie myMovie;
GLTexture tex;
public BGvideo (String videoFile, PApplet app) {
app.registerDraw(this);
myMovie = new GSMovie(app, videoFile );
tex = new GLTexture(app);
myMovie.setPixelDest(tex);
myMovie.loop();
}
public void draw () {
myMovie.read();
if (tex.putPixelsIntoTexture()) {
background(255, 0, 0);
image(tex, 0, 0, 1920, 487);
}
}
}

chafff

Re: Processing 2.0 video alpha channel

6 months ago

Hello Akiersky

thank you very much for your code !

I'm trying to use it but I don't get it. I think I do it in a very wrong way >

import processing.opengl.*;
import codeanticode.gsvideo.*;
import codeanticode.glgraphics.*;
BGvideo bgv = new BGvideo ("marsRVBA.mov",app);
void setup(){
size(640,480);
}
void draw(){
bgv;
background(34,231,90);
}
public class BGvideo {
GSMovie myMovie;
GLTexture tex;
public BGvideo (String videoFile, PApplet app) {
app.registerDraw(this);
myMovie = new GSMovie(app, videofile );
tex = new GLTexture(app);
myMovie.setPixelDest(tex);
myMovie.loop();
}
public void draw () {
myMovie.read();
if (tex.putPixelsIntoTexture()) {
background(255, 0, 0);
image(tex, 0, 0, 1920, 487);
}
}
}

moritz221

Re: Processing 2.0 video alpha channel

6 months ago

Hi everyone!

Same problem with getting your code running, Akiersky. Rendered the *.mov with RGB+ALPHA properties and Animation as you suggested.

    import processing.opengl.*;
    import codeanticode.gsvideo.*;
    import codeanticode.glgraphics.*;

void setup() {
size(600, 400, OPENGL);
frameRate(30);
}

void draw() {
   background(100,100,0);

   BGvideo bgv = new BGvideo("air_argb.mov", app);
   bgv.draw();
}

public class BGvideo {

GSMovie myMovie;
GLTexture tex;

public BGvideo (String videoFile, PApplet app) {

    app.registerDraw(this);

    myMovie = new GSMovie(app, videoFile );
    tex = new GLTexture(app);
    myMovie.setPixelDest(tex);
    myMovie.loop();
}
public void draw () {
    myMovie.read();
    if (tex.putPixelsIntoTexture()) {
      background(255, 0, 0);
      image(tex, 0, 0, 600, 400);
    }
}
}

Comes up with the error:
Cannot find anything named "app"

BGvideo bgv = new BGvideo("air_argb.mov", app);

If I replace 'app' with 'this' it comes up with:
NoSuchFieldError: You may be using a library that's incompatible with this version of Processing.

I'm using Processing 2.08b.

Also tried using the mask() option at first, but have problems syncing up the two videos as stated here:
https://forum.processing.org/topic/videos-with-alpha-mask-sync-problem

akiersky

Re: Processing 2.0 video alpha channel

4 months ago

Hi moritz,

I just saw your post. 'app' was a variable I was using to set the root PApplet in my application. for your example, just change it to 'this' and it should work.

The class, or more specifically, GSVideo needs a PApplet to send it's movieEvent to, so I pass the main PApplet into the class then it can pass it along.

Hope this helps, Good luck

Top Reply