Cannot Change Opencv Webcam Setting

 

I have encountered a problem that when I use opencv API, I cannot change the width and height of

Webcam output:

    cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH, 320);
    cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT, 240);

But after seaching the internet, I have found the key point:

The webcam on linux usually uses the V4L api, and I have not install the library for V4L.

When OpenCV is built, it does not includes the V4L API interface.

 

So, that's the solution:

1.install V4L dev library on ubuntu: libv4l-dev

2. enter opencv sourcecode dir, and reinstall it:

cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local  -D WITH_IPP=OFF ..
make
sudo make install

 After using cmake, I can see the output for V4L:

--   Video I/O:
--     DC1394 1.x:                  NO
--     DC1394 2.x:                  NO
--     FFMPEG:                      YES
--       codec:                     YES (ver 53.35.0)
--       format:                    YES (ver 53.21.1)
--       util:                      YES (ver 51.22.2)
--       swscale:                   YES (ver 2.1.0)
--       gentoo-style:              YES
--     GStreamer:                   NO
--     OpenNI:                      NO
--     OpenNI PrimeSensor Modules:  NO
--     OpenNI2:                     NO
--     PvAPI:                       NO
--     GigEVisionSDK:               NO
--     UniCap:                      NO
--     UniCap ucil:                 NO
--     V4L/V4L2:                    Using libv4l (ver 0.8.6)
--     XIMEA:                       NO
--     Xine:                        NO
-- 

3. After you have rebuilt your program, it will work well.

I can see my 720P camera works well:

 

have fun!

(ibus not installed, can only type english on ubuntu 12.04)