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Hi, all I tested the example from v4l2 website (capture.c) on mini2440. My problem is that when the program is run on the mini2440, the buffer size is not what I expect. The format setting is: fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; fmt.fmt.pix.width = 320; fmt.fmt.pix.height = 240; fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV; fmt.fmt.pix.field = V4L2_FIELD_INTERLACED; The first webcam used is by Vimicro corp(with vid:pid=0ac8:301b). The buffer size(length) = 32768. I guess it was a jpeg result. The second webcam used is PCcam168(with vid:pid=05a9:a511). The buffer size(length) = 233472. 233472>320*24083. What format is it? How can I get data with RGB or YUV format? Or how can I tell if a webcam provides RGB or YUV output, not jpeg output? Thanks!!