求解： VIDIOC_S_CTRL: Numerical result out of range__control_queryctrl_CID_BRIGHTNESS_VIDIOC_S_CTRL_ioctl_

当前位置: 技术问答>linux和unix

求解： VIDIOC_S_CTRL: Numerical result out of range

来源: 互联网发布时间：2017-03-12

本文导语: struct v4l2_queryctrl queryctrl; struct v4l2_control control; memset (&queryctrl, 0, sizeof (queryctrl)); queryctrl.id = V4L2_CID_BRIGHTNESS; i...

struct v4l2_queryctrl queryctrl;
                struct v4l2_control control;

                memset (&queryctrl, 0, sizeof (queryctrl));
                queryctrl.id = V4L2_CID_BRIGHTNESS;

                if (-1 == ioctl (fd, VIDIOC_QUERYCTRL, &queryctrl)) {
                    if (errno != EINVAL) {
                        perror ("VIDIOC_QUERYCTRL");
                        exit (EXIT_FAILURE);
                    } else {
                        printf ("V4L2_CID_BRIGHTNESS is not supportedn");
                    }
                } else if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED) {
                    printf ("V4L2_CID_BRIGHTNESS is not supportedn");
                } else {
                    memset (&control, 0, sizeof (control));
                    control.id = V4L2_CID_BRIGHTNESS;
                    control.value = (__s32)  b;

                    if (-1 == ioctl (fd, VIDIOC_S_CTRL, &control)) {
                        perror ("VIDIOC_S_CTRL");
                        exit (EXIT_FAILURE);
                    }
                }

用GDB调试时发现 ioctl (fd, VIDIOC_S_CTRL, &control) 等于-1

看一下那个ioctl的驱动呀，
control可能这个传入的值不对。

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