Get Image from video

Question

4.00/5 (2 votes)

See more:

Hi,
I am trying to write an application which can access cameras connected to PC, record a video and get an image from the video. I use AForge.NET libraries to access cameras: http://www.aforgenet.com/framework/[^]

I don't know how the event named AForge.Video.NewFrameEventHandler works. In this code the event returns null to a bitmap instead of a new frame from a video or the event is not called. I want to get frames from the video to a picture box every time frame to make something like a video stream and after click on the stop button I want the last image to stay displayed in the picture box. Does anyone know how? And why my code doesn't work?

Code:

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using AForge.Video.DirectShow;
using System.Drawing;
using AForge.Video;

namespace CameraDevice
{
    public class CameraImaging
    {
        // enumerate video devices
        public FilterInfoCollection videoDevices = new FilterInfoCollection(FilterCategory.VideoInputDevice );
        //camera
        public VideoCaptureDevice videoSource;
        //screen shot
        public Bitmap bitmap;
        public CameraImaging()
        {
            // create video source
            VideoCaptureDevice videoSource = new VideoCaptureDevice(videoDevices[0].MonikerString );
            // set NewFrame event handler
            videoSource.NewFrame += new NewFrameEventHandler( video_NewFrame );
        }
        public void StartVideo(VideoCaptureDevice videoSource)
        {
            // start the video source
            videoSource.Start();
            // ...
        }
        public void StopVideo(VideoCaptureDevice videoSource)
        {
            // stop the video source
            videoSource.Stop();
            // ...
        }
        private void video_NewFrame( object sender, NewFrameEventArgs eventArgs )
        {
            // get new frame
            bitmap = eventArgs.Frame;
            // process the frame
        }
    }
}

The similar code is here: http://www.aforgenet.com/framework/features/directshow_video.html[^]

In the Windows Forms I run this video in a thread which does this method:

C#

private void VideoRecording()
{
    camImg.videoSource.Start();

    while (!StopVideo)
    {
        pictureBox1.Image = camImg.bitmap;
        pictureBox1.Invalidate();
    }
    camImg.videoSource.Stop();

}

Thank You for Your replies!

-Pepin z Hané

Posted 18-Oct-12 9:50am

Pepin z Hane

Updated 23-Jan-19 7:42am

Add a Solution

Comments

Sushil Mate 19-Oct-12 0:20am

first of all are you able to capture the video? if yes then event is getting called?
put the debug pointer & check the value of bitmap..

Pepin z Hane 19-Oct-12 3:03am

I am trying to capture the video and I don't know how. I only can recognize camera devices, so the user can choose the camera from a combo box. And I don't know if the event is called. I don't think so, because the bitmap is null during the debuging as I have written.

Sushil Mate 19-Oct-12 3:07am

you need to first grab the video then go for the image frame.. divide the work & try to solve it :)

Pepin z Hane 20-Oct-12 17:08pm

If I had any idea how to do it... :-)

Sushil Mate 21-Oct-12 7:50am

OriginalGriff has the idea, go with it :)

felix pascal 6-Dec-14 16:00pm

hi please the videosource.NewFrame += New AForge.Video.NewFrameEventHandler(video_NewFrame) is not working for me. my visual studio is complaining that: Private Sub video_NewFrame(ByVal sender As Object, ByVal eventArgs As NewFrameEventArgs)is an event and cannot be called directly, use a raise event to raise an event.

If i place that line of code outside my form, it will complain that videosource is not declared whereas i declared it as a dim variable on top my form

please kindly help me out. Thanks

2 solutions

Solution 2

From your brief discussion with Sushil Mate, it appears your problem is pretty basic: you need to break the task up into "chunks" and get the first one working before you move on to the next, just as he says.

Start by getting video capture working! Until you have that, you have nothing to get frames from! :laugh:

This may help: C# \ VB.NET Camera Communication Libraries[^] (you could have found this yourself with a quick Google - it took me only seconds and was the third hit on a simple search: "get video from camera c#")

Posted 20-Oct-12 21:32pm

OriginalGriff

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Pepin z Hane · Accepted Answer · 2012-10-26T09:38:00

I have solved it. In Constructor I have initialized an event, but in Form1 I was overwriting videoSource, so the event wasn't initialized.

The Right code:

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using AForge.Video.DirectShow;
using System.Drawing;
using AForge.Video;


namespace CameraDevice
{
    public class CameraImaging
    {
        // enumerate video devices
        public FilterInfoCollection videoDevices = new FilterInfoCollection(FilterCategory.VideoInputDevice );
        //camera
        private VideoCaptureDevice _videoSource;
        public Bitmap bitmap = new Bitmap(10, 10);
        public VideoCaptureDevice videoSource
        {
            get
            {
                return _videoSource;
            }
            set
            {
                _videoSource = value;
                // set NewFrame event handler
                _videoSource.NewFrame +=new NewFrameEventHandler(videoSource_NewFrame);
            }
        }
        //screen shot
        
        public CameraImaging(VideoCaptureDevice videoDevice)
        {
            // create video source
            VideoCaptureDevice videoSource = videoDevice;
        }
        public CameraImaging()
        {

        }
        private void videoSource_NewFrame( object sender, NewFrameEventArgs eventArgs )
        {
            // get new frame
            lock (bitmap)
            {
                bitmap = (Bitmap)eventArgs.Frame.Clone();
                // process the frame
            }
            
        }
    }
}

Form1:

C#

...
private void VideoRecording()
        {
            camImg.videoSource.Start();
            
            while (!StopVideo)
            {
                lock (mImageLock)
                {
                    Bitmap tmp = (Bitmap)camImg.bitmap.Clone();

                    if (InvokeRequired)
                    {
                        BeginInvoke(new MethodInvoker(() =>
                            {
                                pictureBox1.Image = tmp;
                                pictureBox1.Invalidate();
                            }));
                    }
                    else
                    {
                        pictureBox1.Image = tmp;
                        pictureBox1.Invalidate();
                    }
                }
                Thread.Sleep(33);
            }
            camImg.videoSource.Stop();
            
        }
        private void btnStartVideo_Click(object sender, EventArgs e)
        {
            StopVideo = false;
            try
            {
                camImg.videoSource = new VideoCaptureDevice (camImg.videoDevices[cbCameraDevices.SelectedIndex].MonikerString);
                thrVideo = new Thread(VideoRecording);
                lblRecording.Visible = true;
                thrVideo.Start();
                Thread.Sleep(1000);
            }
            catch (Exception)
            {
                MessageBox.Show("No camera was chosen!", "Exception", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }
            
            
        }
...