Use mjpeg compression

edit

Hi all,

I would like to use the mjpeg compression of my webcam (logitech c920). I can see with $v4l2-ctl --list-formats that MJPEG is supported:

Output:

ioctl: VIDIOC_ENUM_FMT
Index       : 0
Type        : Video Capture
Pixel Format: 'YUYV'
Name        : YUV 4:2:2 (YUYV)

Index       : 1
Type        : Video Capture
Pixel Format: '' (compressed)
Name        : 34363248-0000-0010-8000-00aa003

Index       : 2
Type        : Video Capture
Pixel Format: 'MJPG' (compressed)
Name        : MJPEG

But I tried different ways to set the compression in my code but it doesn't work.

I tried:

cap.set(CV_CAP_PROP_FOURCC, 'M', 'J', 'P', 'G');

which leeds to the outputs that there are to many parameters. Therefore I changed to second parameter like this.

cap.set(CV_CAP_PROP_FOURCC, 2);

This leads to following output:

HIGHGUI ERROR: V4L: Property <unknown property string>(6) not supported by device
HIGHGUI ERROR: V4L2: Unable to get property <unknown property string>(6) - Invalid argument

Would be great to get your help. I appreciate any suggestions.