有的时候接到项目,无非就是想快点的测试手里的驱动到底能不能用,尤其是没有调试过的驱动,现写测试程序,如果不着急还行.最好是能找到能用的,最好就是纯c的,这样简单,又方便调试驱动.
我这里遇到的是v4l2的驱动,想要知到好不好用,就要测试,最简单就是先找一个usb的摄像头来尝试,uvc的驱动大部分bsp都是支持的,插上后,发现有/dev/video0节点产生.接着就是测试,找了好多,也试着自己写,最后还是找到一个能用的,以下代码转载:
https://blog.csdn.net/sanmaoljh/article/details/71128512
测试可以使用,我改了一点点,生成的capture.yuv,可以用工具YUVviewerPlus.exe来播放.这样就能看到v4l2是否成功抓到了图像.
这个工具在网上百度就有下载的. 注意使用的时候,一定要加yuv后缀.具体的设置,我的是这样的,之后open file,点击play就可以了
为了大家方便,写此博客.
#include <unistd.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <sys/ioctl.h> #include <stdlib.h> #include <linux/types.h> #include <linux/videodev2.h> #include <malloc.h> #include <math.h> #include <string.h> #include <sys/mman.h> #include <errno.h> #include <assert.h> #define FILE_VIDEO "/dev/video0" #define JPG "./image%d.yuv" typedef struct{ void *start; int length; } BUFTYPE; BUFTYPE *usr_buf; static unsigned int n_buffer = 0; //set video capture ways(mmap) int init_mmap(int fd) { //to request frame cache, contain requested counts struct v4l2_requestbuffers reqbufs; //request V4L2 driver allocation video cache //this cache is locate in kernel and need mmap mapping memset(&reqbufs, 0, sizeof(reqbufs)); reqbufs.count = 4; reqbufs.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; reqbufs.memory = V4L2_MEMORY_MMAP; if(-1 == ioctl(fd,VIDIOC_REQBUFS,&reqbufs)){ perror("Fail to ioctl 'VIDIOC_REQBUFS'"); exit(EXIT_FAILURE); } n_buffer = reqbufs.count; printf("n_buffer = %d\n", n_buffer); usr_buf = calloc(reqbufs.count, sizeof(BUFTYPE)); if(usr_buf == NULL){ printf("Out of memory\n"); exit(-1); } //map kernel cache to user process for(n_buffer = 0; n_buffer < reqbufs.count; ++n_buffer){ //stand for a frame struct v4l2_buffer buf; memset(&buf, 0, sizeof(buf)); buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_MMAP; buf.index = n_buffer; //check the information of the kernel cache requested if(-1 == ioctl(fd,VIDIOC_QUERYBUF,&buf)) { perror("Fail to ioctl : VIDIOC_QUERYBUF"); exit(EXIT_FAILURE); } usr_buf[n_buffer].length = buf.length; printf("buf.length=%d\n",buf.length); printf("buf.m.offset=%d\n\n",buf.m.offset); //printf("fd=%d\n\n",fd); usr_buf[n_buffer].start = /* (char *)mmap( NULL, buf.length, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, buf.m.offset ); */ (char *)mmap( NULL, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED,//MAP_PRIVATE, fd, buf.m.offset ); printf("usr_buf[%d].start=0x%x\n",n_buffer,usr_buf[n_buffer].start); if(MAP_FAILED == usr_buf[n_buffer].start) { perror("Fail to mmap"); exit(EXIT_FAILURE); } printf("usr_buf %d: address=0x%x, length=%d\n", n_buffer, (unsigned int)usr_buf[n_buffer].start, usr_buf[n_buffer].length); } return 0; } //initial camera device int init_camera_device(int fd) { //decive fuction, such as video input struct v4l2_capability cap; //video standard,such as PAL,NTSC struct v4l2_standard std; //frame format struct v4l2_format tv_fmt; //check control struct v4l2_queryctrl query; //detail control value struct v4l2_fmtdesc fmt; int ret; //get the format of video supply memset(&fmt, 0, sizeof(fmt)); fmt.index = 0; //supply to image capture fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; // show all format of supply printf("Support format:\n"); while(ioctl(fd, VIDIOC_ENUM_FMT, &fmt) == 0) { fmt.index++; printf("pixelformat = ''%c%c%c%c''\ndescription = ''%s''\n",fmt.pixelformat & 0xFF, (fmt.pixelformat >> 8) & 0xFF,(fmt.pixelformat >> 16) & 0xFF,(fmt.pixelformat >> 24) & 0xFF,fmt.description); } //check video decive driver capability ret = ioctl(fd, VIDIOC_QUERYCAP, &cap); if(ret < 0) { perror("Fail to ioctl VIDEO_QUERYCAP"); exit(EXIT_FAILURE); } // Print capability infomations printf("Capability Informations:\n"); printf(" driver: %s\n", cap.driver); printf(" card: %s\n", cap.card); printf(" bus_info: %s\n", cap.bus_info); printf(" version: X\n", cap.version); printf(" capabilities: X\n", cap.capabilities); printf("----------------------------\n"); //judge wherher or not to be a video-get device if(!(cap.capabilities & V4L2_BUF_TYPE_VIDEO_CAPTURE)) { printf("The Current device is not a video capture device\n"); exit(-1); } //judge whether or not to supply the form of video stream if(!(cap.capabilities & V4L2_CAP_STREAMING)) { printf("The Current device does not support streaming i/o\n"); exit(EXIT_FAILURE); } //set the form of camera capture data memset(&tv_fmt, 0, sizeof(tv_fmt)); // very important!must clear 0 tv_fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; tv_fmt.fmt.pix.width = 640; //1280; //680; tv_fmt.fmt.pix.height = 480; //720; //480; tv_fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV; //V4L2_PIX_FMT_YUYV; tv_fmt.fmt.pix.field = V4L2_FIELD_INTERLACED; if (ioctl(fd, VIDIOC_S_FMT, &tv_fmt)< 0) { printf("VIDIOC_S_FMT FAIL!\n"); exit(-1); close(fd); } if(ioctl(fd, VIDIOC_G_FMT, &tv_fmt) < 0) { printf("VIDIOC_G_FMT FAIL!\n"); exit(-1); close(fd); } // Print Stream Format printf("Stream Format Informations:\n"); printf(" type: %d\n", tv_fmt.type); printf(" width: %d\n", tv_fmt.fmt.pix.width); printf(" height: %d\n", tv_fmt.fmt.pix.height); char fmtstr[8]; memset(fmtstr, 0, 8); memcpy(fmtstr, &tv_fmt.fmt.pix.pixelformat, 4); printf(" pixelformat: %s\n", fmtstr); printf(" field: %d\n", tv_fmt.fmt.pix.field); printf(" bytesperline: %d\n", tv_fmt.fmt.pix.bytesperline); printf(" sizeimage: %d\n", tv_fmt.fmt.pix.sizeimage); printf(" colorspace: %d\n", tv_fmt.fmt.pix.colorspace); printf(" priv: %d\n", tv_fmt.fmt.pix.priv); printf(" raw_date: %s\n", tv_fmt.fmt.raw_data); //initial video capture way(mmap) init_mmap(fd); return 0; } int open_camera_device() { int fd; //open video device with block fd = open(FILE_VIDEO, O_RDWR,0); if(fd < 0) { perror(FILE_VIDEO); exit(EXIT_FAILURE); } return fd; } int start_capture(int fd) { unsigned int i; enum v4l2_buf_type type; //place the kernel cache to a queue for(i = 0; i < n_buffer; i++) { struct v4l2_buffer buf; memset(&buf, 0, sizeof(buf)); buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_MMAP; buf.index = i; if(-1 == ioctl(fd, VIDIOC_QBUF, &buf)) { perror("Fail to ioctl 'VIDIOC_QBUF'"); exit(EXIT_FAILURE); } } //start capture data type = V4L2_BUF_TYPE_VIDEO_CAPTURE; if(-1 == ioctl(fd, VIDIOC_STREAMON, &type)) { printf("i=%d.\n", i); perror("VIDIOC_STREAMON"); close(fd); exit(EXIT_FAILURE); } return 0; } #if 0 int process_image(void *addr, int length) { FILE *fp; static int num = 0; char image_name[20]; sprintf(image_name, JPG, num++); if((fp = fopen(image_name, "w")) == NULL){ perror("Fail to fopen"); exit(EXIT_FAILURE); } fwrite(addr, length, 1, fp); usleep(500); fclose(fp); return 0; } #else int process_image(void *addr, int length) { FILE *fp; FILE *fptest; int tmp=0; static int num = 0; char image_name[20]="capture.yuv"; //sprintf(image_name, JPG, num++); //printf("image_name=%s\n",image_name); if((fp = fopen(image_name, "a+")) == NULL){ perror("Fail to fopen"); exit(EXIT_FAILURE); } // #if 0 //debug if((fptest = fopen("test.img", "w")) == NULL){ perror("Fail to fopen"); exit(EXIT_FAILURE); } if(length != fwrite(addr, 1,length, fptest)) { printf("debugfwrite a frame image fail!\n"); } usleep(500); fclose(fptest); #endif // tmp = fwrite(addr, 1,length, fp); printf("tmp=0x%x\n",tmp); if(length != tmp) { printf("fwrite a frame image fail!\n"); } usleep(500); fclose(fp); return 0; } #endif int read_frame(int fd) { struct v4l2_buffer buf; unsigned int i; memset(&buf, 0, sizeof(buf)); buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_MMAP; //put cache from queue if(-1 == ioctl(fd, VIDIOC_DQBUF,&buf)){ perror("Fail to ioctl 'VIDIOC_DQBUF'"); exit(EXIT_FAILURE); } assert(buf.index < n_buffer); printf("buf.index=%d,n_buffer=%d\n",buf.index,n_buffer); printf(" usr_buf[%d].start=0x%x,usr_buf[%d].length=0x%x\n", buf.index,usr_buf[buf.index].start,buf.index,usr_buf[buf.index].length); //read process space's data to a file process_image(usr_buf[buf.index].start, usr_buf[buf.index].length); if(-1 == ioctl(fd, VIDIOC_QBUF,&buf)) { perror("Fail to ioctl 'VIDIOC_QBUF'"); exit(EXIT_FAILURE); } return 1; } int mainloop(int fd) { int count = 60; while(count-- > 0) { for(;;) { fd_set fds; struct timeval tv; int r; FD_ZERO(&fds); FD_SET(fd,&fds); /*Timeout*/ tv.tv_sec = 2; tv.tv_usec = 0; r = select(fd + 1,&fds,NULL,NULL,&tv); if(-1 == r) { if(EINTR == errno) continue; perror("Fail to select"); exit(EXIT_FAILURE); } if(0 == r) { fprintf(stderr,"select Timeout\n"); exit(-1); } if(read_frame(fd)) break; } } return 0; } void stop_capture(int fd) { enum v4l2_buf_type type; type = V4L2_BUF_TYPE_VIDEO_CAPTURE; if(-1 == ioctl(fd,VIDIOC_STREAMOFF,&type)) { perror("Fail to ioctl 'VIDIOC_STREAMOFF'"); exit(EXIT_FAILURE); } return; } void close_camera_device(int fd) { unsigned int i; for(i = 0;i < n_buffer; i++) { if(-1 == munmap(usr_buf[i].start,usr_buf[i].length)) { exit(-1); } } free(usr_buf); if(-1 == close(fd)) { perror("Fail to close fd"); exit(EXIT_FAILURE); } return; } int fd; int main() { fd = open_camera_device(); init_camera_device(fd); start_capture(fd); mainloop(fd); stop_capture(fd); close_camera_device(fd); return 0; }
