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linux v4l 编程(3) V4L2 查询操作

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2012-06-26 20:43:22

原文地址：linux v4l 编程(3) V4L2 查询操作 作者：bluedrum

Andrew Huang 转载请注明作者及网址


一.设备性能查询

在V4L第二步,对用ioctl来查询设备属性和配置,

这里我们用VIDIOC_QUERYCAP来进设备属性查询操作,这是一个v4l2设备必须实现的操作


这里使用 
   ret = ioctl(fd, VIDIOC_QUERYCAP, &cap);
这里查询的结果保存在数据结构
  struct v4l2_capability cap;当中,它有如下定义

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];
};



另外硬件视频数据输入的参数,可以用VIDIOC_ENUMINPUT来做多次查询.
struct v4l2_input input;
  int ret;
  memset(&input, 0, sizeof(input));//initialize i.index=0;

  PRINT_V4L("inputs\n");
  
  while(ret=ioctl(fd, VIDIOC_ENUMINPUT, &input)>=0)
  {
   }

其中使用v4l2_input 数据结构定义如下

/*
 *    V I D E O I N P U T S
 */
struct v4l2_input {
    __u32     index;        /* Which input */
    __u8     name[32];        /* Label */
    __u32     type;        /* Type of input */
    __u32     audioset;        /* Associated audios (bitfield) */
    __u32 tuner; /* Associated tuner */
    v4l2_std_id std;
    __u32     status;
    __u32     reserved[4];
};



2.视频格式查询
  在 v4l2中,有两种查询视频格式的方法,一个遍历所有视频格式的, 一次查询出一种格式的,使用ioctl VIDIOC_ENUM_FMT
 
  1. struct v4l2_fmtdesc fmtdesc;
  2.    int i=0;
  3.    memset(&fmtdesc, 0, sizeof(fmtdesc));

  5.    for(i=0;;i++)
  6.        {     
  7.      fmtdesc.index = i;
  8.       fmtdesc.type = type;
  9.     
  10.      if(-1== ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc))
  11.         break;
  12.     }

 
另外是一次性查询所有格式用,VIDIOC_G_FMT
 
  1. struct v4l2_format format;
  2.     memset(&format,0,sizeof(format));
  3.     format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
  4.          if (-1 == ioctl(fd,VIDIOC_G_FMT,&format))
  5.          {
  6.              perror("VIDIOC_G_FMT(VIDEO_CAPTURE)");
  7.              return -1;
  8.          }

2.具体代码
 
  1. /*
  2.  * Author: Andrew Huang <bluedrum@163.com>
  3.  * query v4l2 device capabilities
  4.  * date: 2010/06/16
  5.  */
  6. #include <stdio.h>
  7. #include <string.h>
  8. #include <errno.h>

  10. #include <sys/types.h>
  11. #include <sys/stat.h>
  12. #include <fcntl.h>

  14. #include <linux/videodev2.h>

  16. #define PRINT_V4L printf

  18. #define PRINT_IOCTL_CMD(cmd) printf(" %15s = (0x%x)\n",#cmd,cmd)
  19. #define PRINT_IOCTL_CMD2(cmd,n) printf(" %-20s(%d) = (0x%x)\n",#cmd,n,cmd)

  21. #define PRINT_V4L_MEMBER(m) printf(" %-20s:",#m);
  22. #define PRINT_V4L_STRING(m) printf(" %-20s:\"%s\"\n",#m,m)
  23. #define PRINT_V4L_INT(m) printf(" %-20s:%d\n",#m,m)
  24. #define PRINT_V4L_INTX(m) printf(" %-20s:0x%x\n",#m,m)

  26. /* 显示enum 值的之一*/
  27. #define TEST_V4L_FLAG0(m,f) printf("%s",((m & f)==f)?#f:"")

  29. /* 显示一个组合值的所有内容 */
  30. #define PRINT_V4L_FLAGS(m) printf(" %-20s:0x%x [",#m,m) /* 组合值开始*/
  31. #define TEST_V4L_FLAG(m,f) printf("%s",((m & f)==f)?#f",":"") /* 组合值中间值,可以有多个*/
  32. #define PRINT_V4L_FLAGS2(m) printf("]\n") /* 组合值结束*/


  35. #define PRINT_INT(e) printf("%s=%d\n",#e,e)




  40. int v4l2_query_video_cap(int fd)
  41. {
  42.  int ret;
  43. struct v4l2_capability cap;
  44. ret = ioctl(fd, VIDIOC_QUERYCAP, &cap);
  45. if(ret < 0)
  46.     {
  47.      printf("get vidieo capability error,error code: %d \n", errno);
  48.      return ret;
  49.     }
  50.     PRINT_V4L("general info\n");
  51.     PRINT_IOCTL_CMD(VIDIOC_QUERYCAP);

  53.     PRINT_V4L_STRING(cap.driver);
  54.     PRINT_V4L_STRING(cap.card);
  55.     PRINT_V4L_STRING(cap.bus_info);
  56.     PRINT_V4L_MEMBER(cap.version);printf("%u.%u.%u\n",(cap.version>>16)&0XFF, (cap.version>>8)&0XFF,cap.version&0xFF);
  57.     
  58.     PRINT_V4L_FLAGS(cap.capabilities);    
  59.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_VIDEO_CAPTURE);
  60.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_VIDEO_OUTPUT);
  61.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_VIDEO_OVERLAY);
  62.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_VBI_CAPTURE);
  63.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_VBI_OUTPUT);
  64.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_SLICED_VBI_CAPTURE);
  65.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_SLICED_VBI_OUTPUT);
  66.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_RDS_CAPTURE);
  67.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_VIDEO_OUTPUT_OVERLAY);
  68.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_HW_FREQ_SEEK);
  69.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_TUNER);
  70.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_AUDIO);
  71.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_RADIO);
  72.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_READWRITE);
  73.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_ASYNCIO);
  74.     TEST_V4L_FLAG(cap.capabilities,V4L2_CAP_STREAMING);

  76.     PRINT_V4L_FLAGS2(cap.capabilities);
  77.    return 0;

  79. }

  81. static void _show_capture_type(enum v4l2_buf_type type)
  82. {
  83.        TEST_V4L_FLAG(type,V4L2_BUF_TYPE_VIDEO_CAPTURE);
  84.         TEST_V4L_FLAG(type,V4L2_BUF_TYPE_VIDEO_OUTPUT);
  85.         TEST_V4L_FLAG(type,V4L2_BUF_TYPE_VIDEO_OVERLAY);
  86.         TEST_V4L_FLAG(type,V4L2_BUF_TYPE_VBI_CAPTURE);
  87.         TEST_V4L_FLAG(type,V4L2_BUF_TYPE_VBI_OUTPUT);
  88.         TEST_V4L_FLAG(type,V4L2_BUF_TYPE_SLICED_VBI_CAPTURE);
  89.         TEST_V4L_FLAG(type,V4L2_BUF_TYPE_SLICED_VBI_OUTPUT);
  90.         TEST_V4L_FLAG(type,V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY);
  91.         TEST_V4L_FLAG(type,V4L2_BUF_TYPE_PRIVATE);    
  92. }


  95. //void show_video_std(v4l2_std_id std)
  96. void show_video_std(v4l2_std_id std)
  97. {
  98. // printf("%s:std=%x\n",__FUNCTION__,std);
  99.   TEST_V4L_FLAG(std,V4L2_STD_PAL_B);
  100.     TEST_V4L_FLAG(std,V4L2_STD_PAL_B1);
  101.     TEST_V4L_FLAG(std,V4L2_STD_PAL_G);
  102.     TEST_V4L_FLAG(std,V4L2_STD_PAL_H);
  103.     TEST_V4L_FLAG(std,V4L2_STD_PAL_I);
  104.     TEST_V4L_FLAG(std,V4L2_STD_PAL_D);
  105.     TEST_V4L_FLAG(std,V4L2_STD_PAL_D1);
  106.     TEST_V4L_FLAG(std,V4L2_STD_PAL_M);
  107.     TEST_V4L_FLAG(std,V4L2_STD_PAL_N);
  108.     TEST_V4L_FLAG(std,V4L2_STD_PAL_Nc);
  109.     TEST_V4L_FLAG(std,V4L2_STD_PAL_60);
  110.     TEST_V4L_FLAG(std,V4L2_STD_NTSC_M);
  111.     TEST_V4L_FLAG(std,V4L2_STD_NTSC_M_JP);
  112.     TEST_V4L_FLAG(std,V4L2_STD_NTSC_443);
  113.     TEST_V4L_FLAG(std,V4L2_STD_NTSC_M_KR);
  114.     TEST_V4L_FLAG(std,V4L2_STD_SECAM_B);
  115.     TEST_V4L_FLAG(std,V4L2_STD_SECAM_D);
  116.     TEST_V4L_FLAG(std,V4L2_STD_SECAM_G);
  117.     TEST_V4L_FLAG(std,V4L2_STD_SECAM_H);
  118.     TEST_V4L_FLAG(std,V4L2_STD_SECAM_K);
  119.     TEST_V4L_FLAG(std,V4L2_STD_SECAM_K1);
  120.     TEST_V4L_FLAG(std,V4L2_STD_SECAM_L);
  121.     TEST_V4L_FLAG(std,V4L2_STD_SECAM_LC);
  122.     TEST_V4L_FLAG(std,V4L2_STD_ATSC_8_VSB);
  123.     TEST_V4L_FLAG(std,V4L2_STD_ATSC_16_VSB);
  124. }



  128. int v4l2_enum_video_input(int fd)
  129. {
  130.   struct v4l2_input input;
  131.   int ret;
  132.   memset(&input, 0, sizeof(input));//initialize i.index=0;

  134.   PRINT_V4L("inputs\n");
  135.   
  136.   while(ret=ioctl(fd, VIDIOC_ENUMINPUT, &input)>=0)
  137.   {
  138.     PRINT_IOCTL_CMD2(VIDIOC_ENUMINPUT,input.index);
  139.     PRINT_V4L_INT(input.index);
  140.     PRINT_V4L_STRING(input.name);
  141.     
  142.     PRINT_V4L_MEMBER(input.type);
  143.     TEST_V4L_FLAG0(input.type,V4L2_INPUT_TYPE_TUNER);
  144.     TEST_V4L_FLAG0(input.type,V4L2_INPUT_TYPE_CAMERA);
  145.     PRINT_V4L("\n");

  147.     PRINT_V4L_INT(input.audioset);    
  148.     PRINT_V4L_INT(input.tuner);



  152.     PRINT_V4L_FLAGS(input.std);
  153.     
  154.     show_video_std(input.std);
  155.     PRINT_V4L_FLAGS2(input.std);
  156.     
  157.     
  158.    //printf("input i.name:%s; i.index :%d i.type = %s\n",i.name, i.index, i.type);
  159.    input.index++;
  160.   }

  162.   return ret;
  163. }

  165. static void _show_pixel_format(unsigned int pixelformat )
  166. {
  167.     if(pixelformat == 0)
  168.         {
  169.          printf("unknow pixelformat %d\n",pixelformat);
  170.          return ;
  171.         }
  172.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_RGB332);
  173.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_RGB444);
  174.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_RGB555);
  175.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_RGB565);
  176.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_RGB555X);
  177.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_RGB565X);
  178.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_BGR24);
  179.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_RGB24);
  180.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_BGR32);
  181.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_RGB32);
  182.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_GREY);
  183.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_Y16);
  184.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_PAL8);
  185.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YVU410);
  186.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YVU420);
  187.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YUYV);
  188.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_UYVY);
  189.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YUV422P);
  190.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YUV411P);
  191.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_Y41P);
  192.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YUV444);
  193.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YUV555);
  194.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YUV565);
  195.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YUV32);
  196.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_NV12);
  197.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_NV21);
  198.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YUV410);
  199.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YUV420);
  200.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YYUV);
  201.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_HI240);
  202.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_HM12);
  203.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SBGGR8);
  204.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SGBRG8);
  205.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SGRBG10);
  206.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SGRBG10DPCM8);
  207.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SBGGR16);
  208.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_MJPEG);
  209.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_JPEG);
  210.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_DV);
  211.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_MPEG);
  212.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_WNVA);
  213.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SN9C10X);
  214.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_PWC1);
  215.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_PWC2);
  216.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_ET61X251);
  217.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SPCA501);
  218.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SPCA505);
  219.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SPCA508);
  220.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_SPCA561);
  221.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_PAC207);
  222.         TEST_V4L_FLAG(pixelformat,V4L2_PIX_FMT_YVYU);    
  223. }

  225. int v4l2_enum_video_format(int fd,enum v4l2_buf_type type,char * title)
  226. {
  227.    struct v4l2_fmtdesc fmtdesc;
  228.    int i=0;
  229.    memset(&fmtdesc, 0, sizeof(fmtdesc));
  230.    


  233.    PRINT_V4L("%s\n",title);

  235.    for(i=0;;i++)
  236.        {
  237.        
  238.      fmtdesc.index = i;
  239.       fmtdesc.type = type;
  240.     
  241.      if(-1== ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc))
  242.         break;
  243.    
  244.        
  245.               
  246.         PRINT_IOCTL_CMD(VIDIOC_ENUM_FMT);
  247.         PRINT_V4L_INT(fmtdesc.index);
  248.         
  249.         PRINT_V4L_FLAGS(fmtdesc.type);
  250.         _show_capture_type(fmtdesc.type);
  251.         PRINT_V4L_FLAGS2(fmtdesc.type);

  253.         PRINT_V4L_INT(fmtdesc.flags);
  254.         PRINT_V4L_STRING(fmtdesc.description);


  257.         PRINT_V4L_FLAGS(fmtdesc.pixelformat);
  258.         _show_pixel_format(fmtdesc.pixelformat);    
  259.         PRINT_V4L_FLAGS2(fmtdesc.pixelformat);

  261.         

  263.         
  264.      
  265.        
  266.        }
  267.   return i;
  268.   
  269. }

  271. #define v4l2_enum_foramt(fd,type) v4l2_enum_video_format(fd,type,#type)
  272. #define v4l2_enum_video_capture(fd) v4l2_enum_foramt(fd,V4L2_BUF_TYPE_VIDEO_CAPTURE)
  273. #define v4l2_enum_video_overlay(fd) v4l2_enum_foramt(fd,V4L2_BUF_TYPE_VIDEO_OVERLAY)
  274. #define v4l2_enum_video_vbi_capture(fd) v4l2_enum_foramt(fd,V4L2_CAP_VBI_CAPTURE)



  278. void _show_v4l2_field(unsigned v4l2_filed)
  279. {
  280.       PRINT_V4L_MEMBER(v4l2_filed);
  281.       TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_ANY);
  282.      TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_NONE);
  283.      TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_TOP);
  284.      TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_BOTTOM);
  285.      TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_INTERLACED);
  286.      TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_SEQ_TB);
  287.      TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_SEQ_BT);
  288.      TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_ALTERNATE);
  289.      TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_INTERLACED_TB);
  290.      TEST_V4L_FLAG0(v4l2_filed,V4L2_FIELD_INTERLACED_BT);
  291.      PRINT_V4L("\n");
  292. }

  294. int v4l2_get_capture_format(int fd)
  295. {
  296.     struct v4l2_format format;
  297.     memset(&format,0,sizeof(format));
  298.     format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
  299.          if (-1 == ioctl(fd,VIDIOC_G_FMT,&format))
  300.          {
  301.              perror("VIDIOC_G_FMT(VIDEO_CAPTURE)");
  302.              return -1;
  303.          }

  305.      PRINT_IOCTL_CMD(VIDIOC_G_FMT);
  306.      PRINT_V4L_FLAGS(format.type);
  307.      _show_capture_type(format.type);
  308.      PRINT_V4L_FLAGS2(format.type);


  311.     
  312.      PRINT_V4L_INT(format.fmt.pix.width);
  313.      PRINT_V4L_INT(format.fmt.pix.height);
  314.      _show_pixel_format(format.fmt.pix.pixelformat);
  315.     
  316.      PRINT_V4L_INT(format.fmt.pix.bytesperline);
  317.      PRINT_V4L_INT(format.fmt.pix.sizeimage);

  319.     

  321.      _show_v4l2_field(format.fmt.pix.field);

  323.     

  325.     return 0;        
  326. }

  328. int main(int argc,char * argv[])
  329. {
  330.    char dev_name[64] = "/dev/video0";
  331.    int cam_fd =-1;

  333.    if(argc>1)
  334.        {
  335.         strncpy(dev_name,argv[1],sizeof(dev_name)-1);
  336.        }

  338.    printf("open device %s\n",dev_name);
  339.     cam_fd = open(dev_name,O_RDWR|O_NONBLOCK);

  341.     if(cam_fd == -1)
  342.         {
  343.          printf("open failure \n");
  344.          return -1;
  345.         }


  348.     printf("### v4l2 device info [%s] ###\n",dev_name);

  350.     
  351.    v4l2_query_video_cap(cam_fd);
  352.    v4l2_enum_video_input(cam_fd);

  354.   v4l2_enum_video_capture(cam_fd);
  355.    

  357.    v4l2_get_capture_format(cam_fd);
  358.     close(cam_fd);

  360.    return 0;
  361.     
  362. }

4.测试样例:
   
  1. [root@FriendlyARM 3]# ./test_v4l2 /dev/video0
  2. open device /dev/video0
  3. ### v4l2 device info [/dev/video0] ###
  4. general info
  5. VIDIOC_QUERYCAP = (0x80685600)
  6. cap.driver :"Samsung FIMC Dris3c-fimc0"
  7. cap.card :"s3c-fimc0"
  8. cap.bus_info :"FIMC AHB-bus"
  9. cap.version :0.0.0
  10. cap.capabilities :0x4000005 [V4L2_CAP_VIDEO_CAPTURE,V4L2_CAP_VIDEO_OVERLAY,V4L2_CAP_STREAMING,]
  11. inputs
  12. VIDIOC_ENUMINPUT (0) = (0xc050561a)
  13. input.index :0
  14. input.name :"External Camera Input"
  15. input.type :V4L2_INPUT_TYPE_CAMERA
  16. input.audioset :1
  17. input.tuner :0
  18. input.std :0x1007 [V4L2_STD_PAL_B,V4L2_STD_PAL_B1,V4L2_STD_PAL_G,V4L2_STD_NTSC_M,]
  19. VIDIOC_ENUMINPUT (1) = (0xc050561a)
  20. input.index :1
  21. input.name :"Memory Input"
  22. input.type :V4L2_INPUT_TYPE_CAMERA
  23. input.audioset :2
  24. input.tuner :0
  25. input.std :0x1007 [V4L2_STD_PAL_B,V4L2_STD_PAL_B1,V4L2_STD_PAL_G,V4L2_STD_NTSC_M,]
  26. VIDIOC_G_FMT = (0xc0cc5604)
  27. format.type :0x1 [V4L2_BUF_TYPE_VIDEO_CAPTURE,]
  28. format.fmt.pix.width:0
  29. format.fmt.pix.height:0
  30. unknow pixelformat 0
  31. format.fmt.pix.bytesperline:0
  32. format.fmt.pix.sizeimage:0
  33. v4l2_filed :V4L2_FIELD_ANY
  34. [root@FriendlyARM 3]#
  35. ----------------------------------------------------------------------------------------------------------------

  37. [root@FriendlyARM 3]# ./test_v4l2 /dev/video1
  38. open device /dev/video1
  39. ### v4l2 device info [/dev/video1] ###
  40. general info
  41. VIDIOC_QUERYCAP = (0x80685600)
  42. cap.driver :"Samsung FIMC Dris3c-fimc1"
  43. cap.card :"s3c-fimc1"
  44. cap.bus_info :"FIMC AHB-bus"
  45. cap.version :0.0.0
  46. cap.capabilities :0x4000005 [V4L2_CAP_VIDEO_CAPTURE,V4L2_CAP_VIDEO_OVERLAY,V4L2_CAP_STREAMING,]
  47. inputs
  48. VIDIOC_ENUMINPUT (0) = (0xc050561a)
  49. input.index :0
  50. input.name :"External Camera Input"
  51. input.type :V4L2_INPUT_TYPE_CAMERA
  52. input.audioset :1
  53. input.tuner :0
  54. input.std :0x1007 [V4L2_STD_PAL_B,V4L2_STD_PAL_B1,V4L2_STD_PAL_G,V4L2_STD_NTSC_M,]
  55. VIDIOC_ENUMINPUT (1) = (0xc050561a)
  56. input.index :1
  57. input.name :"Memory Input"
  58. input.type :V4L2_INPUT_TYPE_CAMERA
  59. input.audioset :2
  60. input.tuner :0
  61. input.std :0x1007 [V4L2_STD_PAL_B,V4L2_STD_PAL_B1,V4L2_STD_PAL_G,V4L2_STD_NTSC_M,]
  62. VIDIOC_G_FMT = (0xc0cc5604)
  63. format.type :0x1 [V4L2_BUF_TYPE_VIDEO_CAPTURE,]
  64. format.fmt.pix.width:0
  65. format.fmt.pix.height:0
  66. unknow pixelformat 0
  67. format.fmt.pix.bytesperline:0
  68. format.fmt.pix.sizeimage:0
  69. v4l2_filed :V4L2_FIELD_ANY
  70. [root@FriendlyARM 3]#


  73. --------------------------------------------------------------------------------------------------------------------------

  75. [root@FriendlyARM 3]# ./test_v4l2 /dev/video2
  76. open device /dev/video2
  77. ### v4l2 device info [/dev/video2] ###
  78. general info
  79. VIDIOC_QUERYCAP = (0x80685600)
  80. cap.driver :"zc3xx"
  81. cap.card :"PC Camera"
  82. cap.bus_info :"s3c24xx"
  83. cap.version :2.3.0
  84. cap.capabilities :0x5000001 [V4L2_CAP_VIDEO_CAPTURE,V4L2_CAP_READWRITE,V4L2_CAP_STREAMING,]
  85. inputs
  86. VIDIOC_ENUMINPUT (0) = (0xc050561a)
  87. input.index :0
  88. input.name :"zc3xx"
  89. input.type :V4L2_INPUT_TYPE_CAMERA
  90. input.audioset :0
  91. input.tuner :0
  92. input.std :0x0 []
  93. VIDIOC_G_FMT = (0xc0cc5604)
  94. format.type :0x1 [V4L2_BUF_TYPE_VIDEO_CAPTURE,]
  95. format.fmt.pix.width:640
  96. format.fmt.pix.height:480
  97. V4L2_PIX_FMT_JPEG, format.fmt.pix.bytesperline:640
  98. format.fmt.pix.sizeimage:115790
  99. v4l2_filed :V4L2_FIELD_ANYV4L2_FIELD_NONE
  100. [root@FriendlyARM 3]#
  
更复杂的ioctl里,借鉴了开源项目xrawtv中的v4l_info.c一节,具体代码参见
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