[ros-users] Gumstix, uvc_camera and cv_capture

Cedric Pradalier cedric.pradalier at gmail.com
Thu Feb 10 17:18:08 UTC 2011

Hi list,

I've observed something surprising with a small UVC camera on the
gumstix overo. If I use the camera_node from uvc_camera, I get barely
2 fps in 640x480.
On the other hand, if I make a small application using the opencv
cvCapture function, I get close to 10fps at the same resolution.

Here is the cv code in all its complexity:

            CvCapture* capture = 0;
            capture = cvCaptureFromCAM( -1 );
            IplImage *cv_image = NULL;
            ros::Rate loop_rate(10);
            while (ros::ok())
                cv_image = cvQueryFrame(capture);
                try {
                    image_pub_.publish(bridge_.cvToImgMsg(cv_image, "bgr8"));
                } catch (sensor_msgs::CvBridgeException error) {


On the same camera on my laptop, both cv_capture and uvc_camera
publish at 10 fps.

I guess that means there is something that would need optimisation in
the uvc_camera/camera_node, but for now I'll be fine with just
reporting :-)

Cedric Pradalier

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