一.摄像头（相机）常见参数

Linux下V4L2相关头文件所在路径为/内核源码目录/include/linux/videodev2.h。V4L2相关API文档
白平衡（自动白平衡AWB）及色温、曝光（自动曝光AE、曝光补偿EV）、亮度、对比度、饱和度、色度（色调+饱和度）、锐度（也叫清晰度）、背光补偿（也叫逆光补偿）、增益、对焦等

（注：不同摄像头开放的参数不一致，需提前确认该款摄像头的可调参数，未开放的参数是无法调整的！！！）

常见的 ioctl 命令：

VIDIOC_QUERYCAP     /* 获取设备支持的操作 */
VIDIOC_G_FMT             /* 获取设置支持的视频格式 */
VIDIOC_S_FMT             /* 设置捕获视频的格式 */
VIDIOC_REQBUFS       /* 向驱动提出申请内存的请求 */
VIDIOC_QUERYBUF    /* 向驱动查询申请到的内存 */
VIDIOC_QBUF              /* 将空闲的内存加入可捕获视频的队列 */
VIDIOC_DQBUF           /* 将已经捕获好视频的内存拉出已捕获视频的队
VIDIOC_STREAMON      /* 打开视频流 */
VIDIOC_STREAMOFF    /* 关闭视频流 */
VIDIOC_QUERYCTRL    /* 查询驱动是否支持该命令 */
VIDIOC_G_CTRL         /* 获取当前命令值 */
VIDIOC_S_CTRL         /* 设置新的命令值 */
VIDIOC_G_TUNER     /* 获取调谐器信息 */
VIDIOC_S_TUNER      /* 设置调谐器信息 */
VIDIOC_G_FREQUENCY  /* 获取调谐器频率 */
VIDIOC_S_FREQUENCY  /* 设置调谐器频率 */

linux系统中提供的videodev2.h列出的 ioctl 命令

/**  I O C T L   C O D E S   F O R   V I D E O   D E V I C E S**/
#define VIDIOC_QUERYCAP      _IOR('V',  0, struct v4l2_capability)
#define VIDIOC_RESERVED       _IO('V',  1)
#define VIDIOC_ENUM_FMT         _IOWR('V',  2, struct v4l2_fmtdesc)
#define VIDIOC_G_FMT        _IOWR('V',  4, struct v4l2_format)
#define VIDIOC_S_FMT        _IOWR('V',  5, struct v4l2_format)
#define VIDIOC_REQBUFS      _IOWR('V',  8, struct v4l2_requestbuffers)
#define VIDIOC_QUERYBUF     _IOWR('V',  9, struct v4l2_buffer)
#define VIDIOC_G_FBUF        _IOR('V', 10, struct v4l2_framebuffer)
#define VIDIOC_S_FBUF        _IOW('V', 11, struct v4l2_framebuffer)
#define VIDIOC_OVERLAY       _IOW('V', 14, int)
#define VIDIOC_QBUF     _IOWR('V', 15, struct v4l2_buffer)
#define VIDIOC_EXPBUF       _IOWR('V', 16, struct v4l2_exportbuffer)
#define VIDIOC_DQBUF        _IOWR('V', 17, struct v4l2_buffer)
#define VIDIOC_STREAMON      _IOW('V', 18, int)
#define VIDIOC_STREAMOFF     _IOW('V', 19, int)
#define VIDIOC_G_PARM       _IOWR('V', 21, struct v4l2_streamparm)
#define VIDIOC_S_PARM       _IOWR('V', 22, struct v4l2_streamparm)
#define VIDIOC_G_STD         _IOR('V', 23, v4l2_std_id)
#define VIDIOC_S_STD         _IOW('V', 24, v4l2_std_id)
#define VIDIOC_ENUMSTD      _IOWR('V', 25, struct v4l2_standard)
#define VIDIOC_ENUMINPUT    _IOWR('V', 26, struct v4l2_input)
#define VIDIOC_G_CTRL       _IOWR('V', 27, struct v4l2_control)
#define VIDIOC_S_CTRL       _IOWR('V', 28, struct v4l2_control)
#define VIDIOC_G_TUNER      _IOWR('V', 29, struct v4l2_tuner)
#define VIDIOC_S_TUNER       _IOW('V', 30, struct v4l2_tuner)
#define VIDIOC_G_AUDIO       _IOR('V', 33, struct v4l2_audio)
#define VIDIOC_S_AUDIO       _IOW('V', 34, struct v4l2_audio)
#define VIDIOC_QUERYCTRL    _IOWR('V', 36, struct v4l2_queryctrl)
#define VIDIOC_QUERYMENU    _IOWR('V', 37, struct v4l2_querymenu)
#define VIDIOC_G_INPUT       _IOR('V', 38, int)
#define VIDIOC_S_INPUT      _IOWR('V', 39, int)
#define VIDIOC_G_EDID       _IOWR('V', 40, struct v4l2_edid)
#define VIDIOC_S_EDID       _IOWR('V', 41, struct v4l2_edid)
#define VIDIOC_G_OUTPUT      _IOR('V', 46, int)
#define VIDIOC_S_OUTPUT     _IOWR('V', 47, int)
#define VIDIOC_ENUMOUTPUT   _IOWR('V', 48, struct v4l2_output)
#define VIDIOC_G_AUDOUT      _IOR('V', 49, struct v4l2_audioout)
#define VIDIOC_S_AUDOUT      _IOW('V', 50, struct v4l2_audioout)
#define VIDIOC_G_MODULATOR  _IOWR('V', 54, struct v4l2_modulator)
#define VIDIOC_S_MODULATOR   _IOW('V', 55, struct v4l2_modulator)
#define VIDIOC_G_FREQUENCY  _IOWR('V', 56, struct v4l2_frequency)
#define VIDIOC_S_FREQUENCY   _IOW('V', 57, struct v4l2_frequency)
#define VIDIOC_CROPCAP      _IOWR('V', 58, struct v4l2_cropcap)
#define VIDIOC_G_CROP       _IOWR('V', 59, struct v4l2_crop)
#define VIDIOC_S_CROP        _IOW('V', 60, struct v4l2_crop)
#define VIDIOC_G_JPEGCOMP    _IOR('V', 61, struct v4l2_jpegcompression)
#define VIDIOC_S_JPEGCOMP    _IOW('V', 62, struct v4l2_jpegcompression)
#define VIDIOC_QUERYSTD          _IOR('V', 63, v4l2_std_id)
#define VIDIOC_TRY_FMT          _IOWR('V', 64, struct v4l2_format)
#define VIDIOC_ENUMAUDIO    _IOWR('V', 65, struct v4l2_audio)
#define VIDIOC_ENUMAUDOUT   _IOWR('V', 66, struct v4l2_audioout)
#define VIDIOC_G_PRIORITY    _IOR('V', 67, __u32) /* enum v4l2_priority */
#define VIDIOC_S_PRIORITY    _IOW('V', 68, __u32) /* enum v4l2_priority */
#define VIDIOC_G_SLICED_VBI_CAP _IOWR('V', 69, struct v4l2_sliced_vbi_cap)
#define VIDIOC_LOG_STATUS         _IO('V', 70)
#define VIDIOC_G_EXT_CTRLS  _IOWR('V', 71, struct v4l2_ext_controls)
#define VIDIOC_S_EXT_CTRLS  _IOWR('V', 72, struct v4l2_ext_controls)
#define VIDIOC_TRY_EXT_CTRLS    _IOWR('V', 73, struct v4l2_ext_controls)
#define VIDIOC_ENUM_FRAMESIZES  _IOWR('V', 74, struct v4l2_frmsizeenum)
#define VIDIOC_ENUM_FRAMEINTERVALS _IOWR('V', 75, struct v4l2_frmivalenum)
#define VIDIOC_G_ENC_INDEX       _IOR('V', 76, struct v4l2_enc_idx)
#define VIDIOC_ENCODER_CMD      _IOWR('V', 77, struct v4l2_encoder_cmd)
#define VIDIOC_TRY_ENCODER_CMD  _IOWR('V', 78, struct v4l2_encoder_cmd)

VIDIOC_QUERYCAP

参数控制相关函数及结构体：
函数：ioctl(fd,VIDIOC_QUERYCAP,struct v4l2_streamparm *argp）;

作用：查询设备能力

     struct v4l2_capability {__u8    driver[16];     /* i.e. "bttv" */__u8    card[32];       /* i.e. "Hauppauge WinTV" */__u8    bus_info[32];   /* "PCI:" + pci_name(pci_dev) */__u32   version;        /* should use KERNEL_VERSION() */__u32   capabilities;   /* Device capabilities */__u32   reserved[4];};/*获取摄像头信息*/struct v4l2_capability cap;if (ioctl(cam_fd, VIDIOC_QUERYCAP, &cap) < 0){perror("get info failed!");return -1;}printf("Driver Name:%s\n Card Name:%s\n Bus info:%s\n version:%d\n capabilities:%x\n \n ", cap.driver, cap.card, cap.bus_info,cap.version,cap.capabilities);if ((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == V4L2_CAP_VIDEO_CAPTURE){printf("Device %s: supports capture.\n",DEV_NAME);}if ((cap.capabilities & V4L2_CAP_STREAMING) == V4L2_CAP_STREAMING){printf("Device %s: supports streaming.\n",DEV_NAME);}

VIDIOC_ENUM_FMT

函数：int ioctl(fd, VIDIOC_ENUM_FMT, struct v4l2_fmtdesc *argp);
作用：获取当前驱动支持的视频格式

struct v4l2_fmtdesc
{__u32 index; // 要查询的格式序号，应用程序设置
enum v4l2_buf_type type; // 帧类型，应用程序设置
__u32 flags; // 是否为压缩格式
__u8 description[32]; // 格式名称
__u32 pixelformat; // 格式
__u32 reserved[4]; // 保留
}；栗子：printf("【**********************所有支持的格式：****************************】\n");
struct v4l2_fmtdesc dis_fmtdesc;
dis_fmtdesc.index=0;
dis_fmtdesc.type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
printf("Support format:\n");
while(ioctl(cam_fd,VIDIOC_ENUM_FMT,&dis_fmtdesc)!=-1)
{printf("\t%d.%s\n",dis_fmtdesc.index+1,dis_fmtdesc.description);dis_fmtdesc.index++;
}
printf("\n")；

VIDIOC_QUERYCAP

函数：ioctl(fd,VIDIOC_QUERYCAP,struct v4l2_queryctrl *argp）;
作用：用作查询某些参数的一些属性要求（如最大最小范围，默认值等）

struct v4l2_queryctrl {__u32                id;enum v4l2_ctrl_type  type;__u8                 name[32];  /* Whatever */__s32                minimum;   /* Note signedness */__s32                maximum;__s32                step;__s32                default_value;__u32                flags;__u32                reserved[2];
};

VIDIOC_G_FMT

函数：ioctl(fd,VIDIOC_G_FMT,struct v4l2_format *argp）; //VIDIOC_S_FMT
作用：分辨率、图像采集格式相关设置

struct v4l2_format {enum v4l2_buf_type type;union {struct v4l2_pix_format          pix;     /* V4L2_BUF_TYPE_VIDEO_CAPTURE */struct v4l2_pix_format_mplane   pix_mp;  /* V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE */struct v4l2_window              win;     /* V4L2_BUF_TYPE_VIDEO_OVERLAY */struct v4l2_vbi_format          vbi;     /* V4L2_BUF_TYPE_VBI_CAPTURE */struct v4l2_sliced_vbi_format   sliced;  /* V4L2_BUF_TYPE_SLICED_VBI_CAPTURE */__u8    raw_data[200];                   /* user-defined */} fmt;
};printf("【**********************获取当前格式信息：****************************】\n");Format.type= V4L2_BUF_TYPE_VIDEO_CAPTURE;if(ioctl(cam_fd,VIDIOC_G_FMT,&Format)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf(">>:  %d * %d\n",Format.fmt.pix.width,Format.fmt.pix.height);printf("pix.pixelformat:%c%c%c%c\n", \Format.fmt.pix.pixelformat & 0xFF,\(Format.fmt.pix.pixelformat >> 8) & 0xFF, \(Format.fmt.pix.pixelformat >> 16) & 0xFF,\(Format.fmt.pix.pixelformat >> 24) & 0xFF);printf("\n");

VIDIOC_G_PARM

函数：ioctl(fd,VIDIOC_G_PARM,struct v4l2_streamparm *argp）; //VIDIOC_S_PARM
作用：流相关 (如帧率)

struct v4l2_format {enum v4l2_buf_type type;union {struct v4l2_pix_format          pix;     /* V4L2_BUF_TYPE_VIDEO_CAPTURE */struct v4l2_pix_format_mplane   pix_mp;  /* V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE */struct v4l2_window              win;     /* V4L2_BUF_TYPE_VIDEO_OVERLAY */struct v4l2_vbi_format          vbi;     /* V4L2_BUF_TYPE_VBI_CAPTURE */struct v4l2_sliced_vbi_format   sliced;  /* V4L2_BUF_TYPE_SLICED_VBI_CAPTURE */__u8    raw_data[200];                   /* user-defined */} fmt;
};printf("【**********************获取当前格式信息：****************************】\n");Format.type= V4L2_BUF_TYPE_VIDEO_CAPTURE;if(ioctl(cam_fd,VIDIOC_G_FMT,&Format)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf(">>:  %d * %d\n",Format.fmt.pix.width,Format.fmt.pix.height);printf("pix.pixelformat:%c%c%c%c\n", \Format.fmt.pix.pixelformat & 0xFF,\(Format.fmt.pix.pixelformat >> 8) & 0xFF, \(Format.fmt.pix.pixelformat >> 16) & 0xFF,\(Format.fmt.pix.pixelformat >> 24) & 0xFF);printf("\n");

VIDIOC_G_PARM

函数：ioctl(fd,VIDIOC_G_PARM,struct v4l2_streamparm *argp）; //VIDIOC_S_PARM
作用：流相关 (如帧率)

struct v4l2_streamparm {enum v4l2_buf_type type;union {struct v4l2_captureparm capture;struct v4l2_outputparm  output;__u8    raw_data[200];  /* user-defined */} parm;
};printf("【***********************获取帧率信息**************************】\n");struct v4l2_streamparm Stream_Parm;Stream_Parm.type=V4L2_BUF_TYPE_VIDEO_CAPTURE;if(ioctl(cam_fd,VIDIOC_G_PARM,&Stream_Parm)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf(">>: Frame rate: %u/%u\n",Stream_Parm.parm.capture.timeperframe.numerator,Stream_Parm.parm.capture.timeperframe.denominator);printf("\n");

VIDIOC_G_CTRL

函数：ioctl(fd,VIDIOC_G_CTRL,struct v4l2_control*argp）; //VIDIOC_S_CTRL
作用：参数控制（白平衡、色温、对比度、饱和度、锐度、曝光等，均有该结构控制）

struct v4l2_control {__u32                id;        //id即要控制的参数id（例白平衡ID为V4L2_CID_AUTO_WHITE_BALANCE）__s32                value;
};printf("【**********************设置手动白平衡：******************************】\n");ctrl.id = V4L2_CID_AUTO_WHITE_BALANCE;ctrl.value = V4L2_WHITE_BALANCE_MANUAL ;if(ioctl(cam_fd,VIDIOC_G_CTRL,&ctrl)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf("\n");    /*************设置白平衡色温****************************/printf("【****************设置白平衡色温********************】\n");ctrl.id = V4L2_CID_WHITE_BALANCE_TEMPERATURE;ctrl.value = 5100;if(ioctl(cam_fd,VIDIOC_S_CTRL,&ctrl)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf("\n");printf("【***************设置亮度***************************】\n");ctrl.id= V4L2_CID_BRIGHTNESS;ctrl.value = 40;if(ioctl(cam_fd,VIDIOC_S_CTRL,&ctrl)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf("\n");printf("【***************设置对比度**************************】\n");ctrl.id = V4L2_CID_CONTRAST;ctrl.value= 45;if(ioctl(cam_fd,VIDIOC_S_CTRL,&ctrl)==-1){perror("ioctl");exit(EXIT_FAILURE);}sleep(1);printf("\n");printf("【***************设置饱和度**************************】\n");ctrl.id = V4L2_CID_SATURATION;ctrl.value= 60;if(ioctl(cam_fd,VIDIOC_S_CTRL,&ctrl)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf("\n");printf("【********************设置色度**********************】\n");ctrl.id = V4L2_CID_HUE;ctrl.value = 1;if(ioctl(cam_fd,VIDIOC_S_CTRL,&ctrl)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf("\n");printf("【********************设置锐度**********************】\n");ctrl.id = V4L2_CID_SHARPNESS;ctrl.value = 4;if(ioctl(cam_fd,VIDIOC_S_CTRL,&ctrl)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf("\n");printf("【*******************设置背光补偿******************】\n");ctrl.id = V4L2_CID_BACKLIGHT_COMPENSATION;ctrl.value = 3;if(ioctl(cam_fd,VIDIOC_S_CTRL,&ctrl)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf("\n");printf("【********************设置伽玛值**********************】\n");ctrl.id = V4L2_CID_GAMMA;ctrl.value = 120;if(ioctl(cam_fd,VIDIOC_S_CTRL,&ctrl)==-1){perror("ioctl");exit(EXIT_FAILURE);}printf("\n");

设置曝光值：

首先将曝光模式修改为手动曝光。
设置曝光档次或者具体的曝光值。

例1：得到曝光模式，设置为手动曝光模式

int ret;
struct v4l2_control ctrl;
//得到曝光模式
ctrl.id = V4L2_CID_EXPOSURE_AUTO;
ret = ioctl(Handle, VIDIOC_G_CTRL, &ctrl);if (ret < 0)
{printf("Get exposure auto Type failed\n");return V4L2_UTILS_GET_EXPSURE_AUTO_TYPE_ERR;
}printf("\nGet Exposure Auto Type:[%d]\n", ctrl.value);

//设置曝光模式为手动模式

ctrl.id = V4L2_CID_EXPOSURE_AUTO;
ctrl.value = V4L2_EXPOSURE_MANUAL;  //手动曝光模式
ret = ioctl(Handle, VIDIOC_S_CTRL, &ctrl);
if (ret < 0)
{printf("Get exposure auto Type failed\n"); return V4L2_UTILS_SET_EXPSURE_AUTO_TYPE_ERR; }

例2：在设置为手动模式后，再得到和设置曝光等级

int ret;
struct v4l2_control ctrl;
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); return V4L2_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 exposure failed (%d)\n", ret); return V4L2_UTILS_SET_EXPSURE_ERR;
}

例3：在设置为手动模式后，再得到和设置曝光绝对值：

int ret;
struct v4l2_control ctrl;
ctrl.id = V4L2_CID_EXPOSURE_ABSOLUTE;
ret = ioctl(handle, VIDIOC_G_CTRL, &ctrl);
if (ret < 0)
{printf("Set exposure failed (%d)\n", ret);//return V4L2_UTILS_SET_EXPSURE_ERR;
}printf("\nGet ABS EXP Success:[%d]\n", ctrl.value);sleep(1);//设置曝光绝对值
ctrl.id = V4L2_CID_EXPOSURE_ABSOLUTE;
ctrl.value = 300;  //单位100us
ret = ioctl(handle, VIDIOC_S_CTRL, &ctrl);
if (ret < 0)
{printf("Set exposure failed (%d)\n", ret);//return V4L2_UTILS_SET_EXPSURE_ERR;
}

（以上参数经过测试均能有效设置，但曝光、自动对焦、增益无法设置通过,会出现ioctl: Invalid argument问题，原因未知，如有朋友知晓，诚请赐教，在此先行谢过）。

博客来源

CSDN博主「人间凑数」原文链接：https://blog.csdn.net/qq_41248872/article/details/87928783

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V4L2下摄像头的详细参数调整

V4L2下摄像头的详细参数调整

一.摄像头（相机）常见参数

VIDIOC_QUERYCAP

VIDIOC_ENUM_FMT

VIDIOC_QUERYCAP

VIDIOC_G_FMT

VIDIOC_G_PARM

VIDIOC_G_PARM

VIDIOC_G_CTRL

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