# Video webcam motion detection troubles
**URL:** https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153
**Category:** Processing for Android
**Created:** [December 5, 2019, 2:23pm UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153 "2019-12-05T14:23:16Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@noFae](https://discourse.processing.org/u/noFae)
#### Post date: [December 5, 2019, 2:23pm UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153/1 "2019-12-05T14:23:16Z")
Having difficulties with accessing webcam when using motion detection code.
Webcam works with other applications and when running Processing code, the viewing window is just dark. I tried to used the printArray Capture.list() to select the correct webcam and I do not receive any errors but only get a dark window.
```auto
// Exercise 16-7: Create a sketch that looks for the average location
// of motion. Can you have an ellipse follow your waving hand?
import processing.video.*;
// Variable for capture device
Capture video;
// Previous Frame
PImage prevFrame;
// How different must a pixel be to be a "motion" pixel
float threshold = 50;
void setup() {
fullScreen(P2D, 2);
//size(320, 240);
// Using the default capture device
// Capture camera list
printArray(Capture.list());
video = new Capture(this, Capture.list()[80]);
width = 800;
height = 600;
video.start();
// Create an empty image the same size as the video
prevFrame = createImage(video.width, video.height, RGB);
}
// New frame available from camera
void captureEvent(Capture video) {
// Save previous frame for motion detection!!
prevFrame.copy(video, 0, 0, video.width, video.height, 0, 0, video.width, video.height);
prevFrame.updatePixels();
video.read();
}
void draw() {
background(0);
// You don't need to display it to analyze it!
image(video, 0, 0);
loadPixels();
video.loadPixels();
prevFrame.loadPixels();
// These are the variables we'll need to find the average X and Y
float sumX = 0;
float sumY = 0;
int motionCount = 0;
// Begin loop to walk through every pixel
for (int x = 0; x < video.width; x++ ) {
for (int y = 0; y < video.height; y++ ) {
// What is the current color
color current = video.pixels[x+y*video.width];
// What is the previous color
color previous = prevFrame.pixels[x+y*video.width];
// Step 4, compare colors (previous vs. current)
float r1 = red(current);
float g1 = green(current);
float b1 = blue(current);
float r2 = red(previous);
float g2 = green(previous);
float b2 = blue(previous);
// Motion for an individual pixel is the difference between the previous color and current color.
float diff = dist(r1, g1, b1, r2, g2, b2);
// If it's a motion pixel add up the x's and the y's
if (diff > threshold) {
sumX += x;
sumY += y;
motionCount++;
}
}
}
// average location is total location divided by the number of motion pixels.
float avgX = sumX / motionCount;
float avgY = sumY / motionCount;
// Draw a circle based on average motion
smooth();
noStroke();
fill(255);
ellipse(avgX, avgY, 16, 16);
}
```
I appreciate any support or advice on getting a webcam to work with processing.
---
### Author:  [@noel](https://discourse.processing.org/u/noel)
#### Post date: [December 5, 2019, 2:40pm UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153/2 "2019-12-05T14:40:00Z")
I think you need something like
```auto
video = new Capture (this, width, height);
```
And set the size of the sketch according the smallest configuration possible.
---
### Author:  [@noFae](https://discourse.processing.org/u/noFae)
#### Post date: [December 5, 2019, 4:19pm UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153/3 "2019-12-05T16:19:47Z")
Thanks Noel, your feedback is greatly welcomed.
When trying your recommendation:
video = new Capture (this, width, height);
The video always goes to the default internal camera and not the external web camera. I also need the output to be fullScreen. Unfortunately I was not able to make it work with this recommendation.
---
### Author:  [@noel](https://discourse.processing.org/u/noel)
#### Post date: [December 5, 2019, 4:36pm UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153/4 "2019-12-05T16:36:59Z")
Unfortunately I only have a tablet, thus I can’t test it. I have a working motion detection code for Android with the ketai lib. If you’r interested I’ll post it.
---
### Author:  [@noFae](https://discourse.processing.org/u/noFae)
#### Post date: [December 5, 2019, 4:57pm UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153/5 "2019-12-05T16:57:58Z")
Thanks again noel and I would be happy to learn about the detection code for Android with the ketai lib. I look forward to your post and thanks again!
---
### Author:  [@noel](https://discourse.processing.org/u/noel)
#### Post date: [December 5, 2019, 5:10pm UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153/6 "2019-12-05T17:10:43Z")
Here it is.
You have to give the CAMARA permission to run.
You can test it downloading the app APDE on play store. I’ll take just two minutes.
```auto
// Thanks to
// Daniel Shiffman
// http://www.learningprocessing.com
// Code for Android / Ketai by noel
import ketai.camera.*;
KetaiCamera cam;
PImage prevFrame;
float threshold = 50;
void setup() {
size(320, 240);
cam = new KetaiCamera(this, 320, 240, 31);
// cam.setCameraID(1); // If you want the front camara
cam.start();
prevFrame = createImage(cam.width, cam.height, RGB);
}
void onCameraPreviewEvent() {
prevFrame.copy(cam, 0, 0, cam.width, cam.height, 0, 0, cam.width, cam.height);
prevFrame.updatePixels();
cam.read();
}
void draw() {
background(255);
// You don't need to display it to analyze it!
image(cam, 0, 0);
cam.loadPixels();
prevFrame.loadPixels();
// Start with a total of 0
// These are the variables we'll need to find the average X and Y
float sumX = 0;
float sumY = 0;
int motionCount = 0;
// Begin loop to walk through every pixel
for (int x = 0; x < cam.width; x++ ) {
for (int y = 0; y < cam.height; y++ ) {
// What is the current color
color current = cam.pixels[x+y*cam.width];
// What is the previous color
color previous = prevFrame.pixels[x+y*cam.width];
// Step 4, compare colors (previous vs. current)
float r1 = red(current);
float g1 = green(current);
float b1 = blue(current);
float r2 = red(previous);
float g2 = green(previous);
float b2 = blue(previous);
// Motion for an individual pixel is the difference between the previous color and current color.
float diff = dist(r1, g1, b1, r2, g2, b2);
// If it's a motion pixel add up the x's and the y's
if (diff > threshold) {
sumX += x;
sumY += y;
motionCount++;
}
}
}
// average location is total location divided by the number of motion pixels.
float avgX = sumX / motionCount;
float avgY = sumY / motionCount;
// Draw a circle based on average motion
smooth();
noStroke();
fill(255);
ellipse(avgX, avgY, 16, 16);
}
```
---
### Author:  [@jeremydouglass](https://discourse.processing.org/u/jeremydouglass)
#### Post date: [December 9, 2019, 12:44am UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153/7 "2019-12-09T00:44:04Z")
> [@noFae](#):
>
> video = new Capture(this, Capture.list()[80]);
This line is suspicious. Is your webcam really listed as camera 80?
---
### Author:  [@noFae](https://discourse.processing.org/u/noFae)
#### Post date: [December 10, 2019, 4:37pm UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153/8 "2019-12-10T16:37:38Z")
Hi jeremey, thanks for the concern and according to my captureList, the proper camera format is 80.
If possible, can you dive more into your suspicions?
---
### Author:  [@flotowcameron](https://discourse.processing.org/u/flotowcameron)
#### Post date: [November 29, 2020, 8:54pm UTC](https://discourse.processing.org/t/video-webcam-motion-detection-troubles/16153/9 "2020-11-29T20:54:33Z")
Help! I am trying to connect a usb webcam to android device but can’t seem to get my phone to read webcam input. How can I make this work? I’ll paste my code below.
import ketai.camera.\*;
KetaiCamera cam;
import processing.sound.\*;
SqrOsc soundRed;
Pulse soundGreen;
SinOsc soundBlue;
int gameState = 0;
int count = 0;
float rAmp = 0;
float gAmp = 0;
float bAmp = 0;
boolean sounds = false;
float tempRed = 0;
float tempGreen = 0;
float tempBlue = 0;
float mapRed = 0;
float mapGreen = 0;
float mapBlue = 0;
float soundSpace = 0;
int countThruCameras;
void setup() {
textSize(20);
fullScreen();
orientation(PORTRAIT);
imageMode(CENTER);
soundRed = new SqrOsc(this);
soundRed.amp(0.05);
soundGreen = new Pulse(this);
soundGreen.amp(0.05);
soundBlue = new SinOsc(this);
soundBlue.amp(0.2);
cam = new KetaiCamera(this, 1000, 1500, 60);
cam.setCameraID(80);
textAlign(CENTER, CENTER);
}
void draw() {
if(gameState == 0){
count++;
if(count \>= 200){
gameState = 1;
cam.start();
}
background(255);
}
if (gameState==1) {
```
print(cam.getCameraID());
soundRed.amp(rAmp);
soundGreen.amp(gAmp);
soundBlue.amp(bAmp);
background(0);
translate(width/2, height/2);
pushMatrix();
rotate(HALF_PI);
image(cam, 0,0);
popMatrix();
tempRed = red(get(width/2, height/2));
tempGreen = green(get(width/2, height/2));
tempBlue = blue(get(width/2, height/2));
mapRed = map(tempRed, 0, 255, 1, 200);
mapGreen = map(tempGreen, 0, 255, 0, 450);
mapBlue = map(tempBlue, 0, 255, 1, 500);
rAmp = map(mapRed, 0, 200, 0, .05);
gAmp = map(mapGreen, 0, 450, 0, .05);
bAmp = map(mapBlue, 0, 200, 0, .07);
//soundSpace = (mapRed+mapGreen+mapBlue)/3;
soundRed.freq(mapRed);
soundGreen.freq(mapGreen);
soundBlue.freq(mapBlue);
stroke(255);
strokeWeight(2);
noFill();
ellipse(0, 0, 40, 40);
if (sounds) {
soundRed.play();
soundGreen.play();
soundBlue.play();
} else {
soundRed.stop();
soundGreen.stop();
soundBlue.stop();
fill(0, 0, 0, 180);
stroke(0);
//rect((-width/2)-5, 170, width+5, 60);
fill(0, 200, 255);
text("Click screen to hear color", 0, (height/3)+(height/13));
stroke(255);
}
text(cam.getNumberOfCameras(),0,100);
```
}
}
void onCameraPreviewEvent()
{
cam.read();
}
void mousePressed() {
if(gameState==1){
sounds = !sounds;
}
}