VIDIOC_QUERYMENU: Invalid argument

[vincentsaluzzo]

Hi,

I try to make a little program with the example to take screenshot with my webcam.
I have installed OpenCV and I write this piece of code :

var camera = require('camera');
var fs = require('fs');

var webcam = camera.createStream();

webcam.on('data', function(buffer) {
    fs.writeFileSync('cam.jpg', buffer);
    webcam.destroy();
});

when I execute this code, I have an error :

VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
/home/pi/babycamble/node_modules/camera/lib/main.coffee:1038: Uncaught TypeError: Cannot call method 'toBuffer' of null

and no image was save... a solution ?

[yocontra]

Can you try making writeFileSync async (writeFile) and destroy when it is done writing? I think the underlying opencv binding might not be handling something right here

[vincentsaluzzo]

I will test but the problem seems not appear inside the callback of webcam.on ('data', function ... but when the createStream was called...

[yocontra]

In the README: "createStream optionally takes a camera number and defaults to 0 for the main camera"

Can you try passing in a different number to createStream? It's possible you have a "camera" attached to your computer (physically or virtually) that is messing this up by identifying as your main camera when it isn't

[vincentsaluzzo]

Ok so I have try to pass an another index to createStream (1, 2, etc.) but it seems not resolved the problem :

HIGHGUI ERROR: V4L: index 1 is not correct!

/home/pi/babycamble/node_modules/camera/lib/main.coffee:30
  cam = new cv.VideoCapture(idx);
        ^
Error: Camera could not be opened
    at Object.module.exports.createStream (/home/pi/babycamble/node_modules/camera/lib/main.coffee:30:13)
    at Object.<anonymous> (/home/pi/babycamble/opencv.js:4:21)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.runMain (module.js:492:10)
    at process.startup.processNextTick.process._tickCallback (node.js:244:9)

I have also try to remove the line for writing image to filesystem but the problem always appear...

[yocontra]

What type/model camera do you have plugged in? The data coming back from it is not playing well with OpenCV

[yocontra]

Okay so it looks that error is in fact coming from a camera compatibility issue. Try another camera or open an issue against OpenCV

[vincentsaluzzo]

Okay, this error isn't it ! But it sound like a bug because your library don't use the last VideoCapture API of OpenCV.

--> Changelog

And your seems correct the problem in your last commit ! I will try your last commit now...

[vincentsaluzzo]

Ok, so with your last modification, you've correct the problem ;)