InvalidOperationException - object is currently in use elsewhere?

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C#

stream

image

webcam

recorder

Im using a webcam to show live stream, capture images, record video etc using AForge library.
Each time I get a new frame, I assign it to a pictureBox to show the live stream and i have added a toolstrip for recording video when it is checked. so i did it in the same following method.

private void video_NewFrame( object sender, NewFrameEventArgs eventArgs)
{
// Assigning new frame to a picturebox
pictureBox1.Image = newFrame;

if(recordVideo.Checked)
{
writer.AddFrame(newFrame);
}
}

when the recordVideo toolstrip is checked. I open the avi file
writer.Open("test.avi", pictureBox1.Width, pictureBox1.Height);

and when it is unchecked i close the file.
writer.Close();

but when i start recording the video i get the following error:
InvalidOperationException - object is currently in use elsewhere.