C语言ioctl调摄像头曝光的问题

pirongbing0020 2017-09-13 11:53:39

我是做在开发板上用实现摄像头识别二维码的项目。二维码移到较快所以要调低曝光值，但使用v4l2_control调节的曝光值好像不稳定，open函数打开摄像设备之后曝光不一定是正确的，然后这次开启摄像头曝光就一直不正确，图片明显偏亮，是函数问题（希望给个更好的C实现的方法）还是这个摄像头有问题（SY003淘宝买的100多块）。
这是我调曝光的方法。



int set_exposure(int cam_fd, int exp_value) {

    struct v4l2_control ctrl;

    struct v4l2_queryctrl setting;

    int min, max, current, step, val_def;

    if (isv4l2Control(cam_fd, V4L2_CID_EXPOSURE_ABSOLUTE, &setting) < 0)

        return -1;

    min = setting.minimum;

    max = setting.maximum;

    step = setting.step;

    val_def = setting.default_value;

    current = v4l2GetControl(cam_fd, V4L2_CID_EXPOSURE_ABSOLUTE);

    printf("max %d, min %d, default %d, current %d \n", max, min, val_def,

            current);

    printf("start set exp\n");

    int ret;

    //设置曝光绝对值

    ctrl.id = V4L2_CID_EXPOSURE_ABSOLUTE;

    ctrl.value = exp_value;

    ret = ioctl(cam_fd, VIDIOC_S_CTRL, &ctrl);

    if (ret < 0) {

        printf("Set exposure failed (%d)\n", ret);

        return FALSE;

    } else

        printf("Control name:%s set to value:%d\n", setting.name, ctrl.value);

    return TRUE;

}

这是我试的另一种方法，摄像头不支持



 int ret; 

struct v4l2_controlctrl; 

ctrl.id = V4L2_CID_EXPOSURE; //得到曝光档次，A20接受从 -4到4 共9个档次

ret = ioctl(Handle, VIDIOC_G_CTRL,&ctrl); 

if (ret < 0) 

{ printf("Get exposure failed (%d)\n",ret); 

returnV4L2_UTILS_GET_EXPSURE_ERR; 

} 



printf("\nGet Exposure :[%d]\n",ctrl.value);



//设置曝光档次

ctrl.id = V4L2_CID_EXPOSURE; 

ctrl.value = -4; 

ret = ioctl(Handle, VIDIOC_S_CTRL,&ctrl); 

if (ret < 0) { printf("Set exposurefailed (%d)\n", ret); 

return V4L2_UTILS_SET_EXPSURE_ERR;}