v4l2 camera测试程序 保存成图片
来源：互联网 发布：康熙停播原因 知乎 编辑：程序博客网 时间：2024/05/15 04:44
使用的usb camera 是 0ac8:3420，使用网上找到的代码改
保存在图片，中间的LCD部分可以删了，我还要用就没改。
/* * main.c * * Created on: Apr 25, 2016 * Author: anzyelay */#include <unistd.h>#include <linux/fb.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <assert.h>#include <getopt.h>#include <fcntl.h>#include <unistd.h>#include <errno.h>#include <malloc.h>#include <sys/stat.h>#include <sys/types.h>#include <sys/time.h>#include <sys/mman.h>#include <sys/ioctl.h>#include <asm/types.h>#include <linux/videodev2.h>#include "bmp.h"#define CAMERA_DEVICE "/dev/video0"#define FB_DEVICE "/dev/fb0"#define VIDEO_WIDTH 640#define VIDEO_HEIGHT 480#define BUFFER_COUNT 4typedef struct VideoBuffer { void *start; size_t length;} VideoBuffer;VideoBuffer framebuf[BUFFER_COUNT];//查表法，把YUV422转换为RGB32void process(unsigned long *rgb_buf, unsigned char *v_buf){ int r,g,b; int u,v; int y[2]; int rv,guv,bu,i; unsigned int *fb_buf = (unsigned int *)rgb_buf; y[0]=(int)*v_buf; v=(int)*(v_buf+1); y[1]=(int)*(v_buf+2); u=(int)*(v_buf+3); rv=rvarrxyp[v]; guv=guarrxyp[u]+gvarrxyp[v]; bu=buarrxyp[u]; for(i=0;i<2;i++){ r=y[i]+rv; g=y[i]-guv; b=y[i]+bu; if (r>255) r=255; if (r<0) r=0; if (g>255) g=255; if (g<0) g=0; if (b>255) b=255; if (b<0) b=0; *(fb_buf+i)=(b<<16)+(g<<8)+r; }}int main(){ int i, ret; // 打开摄像头设备 int fd; fd = open(CAMERA_DEVICE, O_RDWR, 0); if (fd < 0) { printf("Open %s failed\n", CAMERA_DEVICE); return -1; } // 获取驱动信息 struct v4l2_capability cap; ret = ioctl(fd, VIDIOC_QUERYCAP, &cap); if (ret < 0) { printf("VIDIOC_QUERYCAP failed (%d)\n", ret); goto __error1; } 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: %u.%u.%u\n", (cap.version>>16)&0XFF, (cap.version>>8)&0XFF,cap.version&0XFF); printf(" capabilities: %08X\n", cap.capabilities); // 设置视频格式 struct v4l2_format fmt; memset(&fmt, 0, sizeof(fmt)); fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; fmt.fmt.pix.width = VIDEO_WIDTH; fmt.fmt.pix.height = VIDEO_HEIGHT; fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV; fmt.fmt.pix.field = V4L2_FIELD_INTERLACED; ret = ioctl(fd, VIDIOC_S_FMT, &fmt); if (ret < 0) { printf("VIDIOC_S_FMT failed (%d)\n", ret); goto __error1; } //获取视频格式(原因是设置视频格式时如果有错误，VIDIOC_S_FMT时会自动转换成合作的格式，所以再获取一次) ret = ioctl(fd, VIDIOC_G_FMT, &fmt); if (ret < 0) { printf("VIDIOC_G_FMT failed (%d)\n", ret); goto __error1; } // Print Stream Format printf("Stream Format Informations:\n"); printf(" type: %d\n", fmt.type); printf(" width: %d\n", fmt.fmt.pix.width); printf(" height: %d\n", fmt.fmt.pix.height); char fmtstr[8]; memset(fmtstr, 0, 8); memcpy(fmtstr, &fmt.fmt.pix.pixelformat, 4); printf(" pixelformat: %s\n", fmtstr); printf(" field: %d\n", fmt.fmt.pix.field); printf(" bytesperline: %d\n", fmt.fmt.pix.bytesperline); printf(" sizeimage: %d\n", fmt.fmt.pix.sizeimage); printf(" colorspace: %d\n", fmt.fmt.pix.colorspace); printf(" priv: %d\n", fmt.fmt.pix.priv); printf(" raw_date: %s\n", fmt.fmt.raw_data);//----------------------------------------------- //请求分配内存 struct v4l2_requestbuffers reqbuf; reqbuf.count = BUFFER_COUNT; reqbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; reqbuf.memory = V4L2_MEMORY_MMAP; ret = ioctl(fd , VIDIOC_REQBUFS, &reqbuf);//在内核虚拟地址空间中申请reqbuf.count个连续的内存 if(ret < 0) { printf("VIDIOC_REQBUFS failed (%d)\n", ret); goto __error1; } struct v4l2_buffer buf; for (i = 0; i < reqbuf.count; i++) { buf.index = i; buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_MMAP; //根据buf.index询访内存为后面的映射做准备（本质就是设置buf.m.offset+=buf.length偏移） ret = ioctl(fd , VIDIOC_QUERYBUF, &buf); if(ret < 0) { printf("VIDIOC_QUERYBUF (%d) failed (%d)\n", i, ret); goto __error1; } //映射到用户空间 //就是将之前内核分配的视频缓冲（VIDIOC_REQBUFS）映射到用户空间，这样用户空间就可以直接读取内核扑获的视频数据 //buf.m.offset表示要对内核中的哪个video buffer进行映射操作 framebuf[i].length = buf.length; framebuf[i].start = (char *) mmap(0, buf.length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, buf.m.offset); if (framebuf[i].start == MAP_FAILED) { printf("mmap (%d) failed: %s\n", i, strerror(errno)); ret = -1; goto __error1; } //内存入队列 ret = ioctl(fd , VIDIOC_QBUF, &buf); if (ret < 0) { printf("VIDIOC_QBUF (%d) failed (%d)\n", i, ret); goto __error2; } printf("Frame buffer %d: address=0x%x, length=%d\n", i, (unsigned long)framebuf[i].start, (unsigned int)framebuf[i].length); }//-------------------------------------- // 启动视频流 enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE; ret = ioctl(fd, VIDIOC_STREAMON, &type); if (ret < 0) { printf("VIDIOC_STREAMON failed (%d)\n", ret); goto __error2; } struct fb_var_screeninfo vinfo; struct fb_fix_screeninfo finfo; int x,y; int fd_fb; long int screen_size = 0; unsigned long *fbp32 = NULL; //打开LCD设备 fd_fb = open(FB_DEVICE, O_RDWR); if (fd_fb < 0) { printf("Error: cannot open framebuffer device.\n"); goto __error2; } if (ioctl(fd_fb, FBIOGET_FSCREENINFO, &finfo)) { printf("Error reading fixed information.\n"); goto __error3; } //获取LCD属性信息 if (ioctl(fd_fb, FBIOGET_VSCREENINFO, &vinfo)) { printf("Error 2 reading variable information.\n"); goto __error3; } //一屏的字节数 screen_size = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8; printf("LCD: %dx%d, %dbpp, screen_size = %ld\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel, screen_size ); //映射framebuffer到用户空间 fbp32 = (unsigned long *)mmap(0, screen_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd_fb, 0); if (fbp32 == MAP_FAILED) { printf("Error: failed to map framebuffer device to memory.\n"); goto __error3; } printf("start camera testing...\n"); //开始视频显示// while(1) unsigned long *picdata = (unsigned long *)malloc(fmt.fmt.pix.height*fmt.fmt.pix.width*4); memset(picdata,0,fmt.fmt.pix.height*fmt.fmt.pix.width*4); for(i=0;i<1;i++) { memset(&buf,0,sizeof(buf)); buf.index = 0; buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_MMAP; //内存空间出队列 ret = ioctl(fd, VIDIOC_DQBUF, &buf); if (ret < 0) { printf("VIDIOC_DQBUF failed (%d)\n", ret); break; } if(vinfo.bits_per_pixel == 32) { //yuv422 两个像素占4个字节（Y0，V，Y1，U），两个像素共用一个UV对，总字节数为W*H*2， //而RGB32则正好两个像素是一个LONG型对齐，以LONG为单位一次可计算两个像素点，之后framebuf自增4个字节地址指向一两个像素点 for(y = 0; y < fmt.fmt.pix.height; y++) { for(x = 0; x < fmt.fmt.pix.width/2; x++) { //YUV422转换为RGB32// process(fbp32 + y*vinfo.xres + x,// (U8 *)framebuf[buf.index].start + (y*fmt.fmt.pix.width+x)*2); //由于是以long为基数自增，所以一行long数为：width(long)=width(int)/2 process((picdata + y*fmt.fmt.pix.width/2 + x), (U8 *)framebuf[buf.index].start + y*fmt.fmt.pix.width*2+x*4); } } } // 内存重新入队列 ret = ioctl(fd, VIDIOC_QBUF, &buf); if (ret < 0) { printf("VIDIOC_QBUF failed (%d)\n", ret); break; } }//while(1) /*save image picture captured*/ char picname[100]; sprintf(picname,"./niu_%d*%d.bmp",fmt.fmt.pix.width,fmt.fmt.pix.height); GenBmpFile((U8 *)picdata,32,fmt.fmt.pix.width,fmt.fmt.pix.height,picname); //释放fbp32资源 munmap(fbp32, screen_size); __error3://关闭fd_fb设备 close(fd_fb); __error2://释放framebuf资源 for (i=0; i< 4; i++) { munmap(framebuf[i].start, framebuf[i].length); } __error1://关闭fd设备 close(fd); return ret;}//------------save image picture captured--------///////int GenBmpFile(U8 *pData, U8 bitCountPerPix, U32 width, U32 height, const char *filename){ FILE *fp = fopen(filename, "wb"); if(!fp) { printf("fopen failed : %s, %d\n", __FILE__, __LINE__); return 0; } U32 bmppitch = ((width*bitCountPerPix + 31) >> 5) << 2; U32 filesize = bmppitch*height; BITMAPFILE bmpfile; bmpfile.bfHeader.bfType = 0x4D42; bmpfile.bfHeader.bfSize = filesize + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER); bmpfile.bfHeader.bfReserved1 = 0; bmpfile.bfHeader.bfReserved2 = 0; bmpfile.bfHeader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER); bmpfile.biInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER); bmpfile.biInfo.bmiHeader.biWidth = width; bmpfile.biInfo.bmiHeader.biHeight = height; bmpfile.biInfo.bmiHeader.biPlanes = 1; bmpfile.biInfo.bmiHeader.biBitCount = bitCountPerPix; bmpfile.biInfo.bmiHeader.biCompression = 0; bmpfile.biInfo.bmiHeader.biSizeImage = filesize; bmpfile.biInfo.bmiHeader.biXPelsPerMeter = 0; bmpfile.biInfo.bmiHeader.biYPelsPerMeter = 0; bmpfile.biInfo.bmiHeader.biClrUsed = 0; bmpfile.biInfo.bmiHeader.biClrImportant = 0; fwrite(&(bmpfile.bfHeader), sizeof(BITMAPFILEHEADER), 1, fp); fwrite(&(bmpfile.biInfo.bmiHeader), sizeof(BITMAPINFOHEADER), 1, fp); fwrite(pData,filesize,1, fp);// U8 *pEachLinBuf = (U8*)malloc(bmppitch);// memset(pEachLinBuf, 0, bmppitch);// U8 BytePerPix = bitCountPerPix >> 3;// U32 pitch = width * BytePerPix;// if(pEachLinBuf)// {// int h,w;// for(h = height-1; h >= 0; h--)// {// for(w = 0; w < width; w++)// {// //copy by a pixel// pEachLinBuf[w*BytePerPix+0] = pData[h*pitch + w*BytePerPix + 0];// pEachLinBuf[w*BytePerPix+1] = pData[h*pitch + w*BytePerPix + 1];// pEachLinBuf[w*BytePerPix+2] = pData[h*pitch + w*BytePerPix + 2];// }// fwrite(pEachLinBuf, bmppitch, 1, fp);//// }// free(pEachLinBuf);// } fclose(fp); return 1;}bmp.h/* * bmp.h * * Created on: Apr 26, 2016 * Author: anzyelay */#ifndef BMP_H_#define BMP_H_#pragma pack(push, 1)typedef unsigned char U8;typedef unsigned short U16;typedef unsigned int U32;typedef struct tagBITMAPFILEHEADER{ U16 bfType; U32 bfSize; U16 bfReserved1; U16 bfReserved2; U32 bfOffBits;} BITMAPFILEHEADER;typedef struct tagBITMAPINFOHEADER{ U32 biSize; U32 biWidth; U32 biHeight; U16 biPlanes; U16 biBitCount; U32 biCompression; U32 biSizeImage; U32 biXPelsPerMeter; U32 biYPelsPerMeter; U32 biClrUsed; U32 biClrImportant;} BITMAPINFOHEADER;typedef struct tagRGBQUAD{ U8 rgbBlue; U8 rgbGreen; U8 rgbRed; U8 rgbReserved;} RGBQUAD;typedef struct tagBITMAPINFO{ BITMAPINFOHEADER bmiHeader; RGBQUAD bmiColors[1];} BITMAPINFO;typedef struct tagBITMAP{ BITMAPFILEHEADER bfHeader; BITMAPINFO biInfo;}BITMAPFILE;#pragma pack(pop)int GenBmpFile(U8 *pData, U8 bitCountPerPix, U32 width, U32 height, const char *filename);//YUV422转换为RGB32表const int rvarrxyp[]={-180,-179,-177,-176,-175,-173,-172,-170,-169,-167,-166,-165,-163,-162,-160,-159,-158,-156,-155,-153,-152,-151,-149,-148,-146,-145,-144,-142,-141,-139,-138,-137,-135,-134,-132,-131,-129,-128,-127,-125,-124,-122,-121,-120,-118,-117,-115,-114,-113,-111,-110,-108,-107,-106,-104,-103,-101,-100,-99,-97,-96,-94,-93,-91,-90,-89,-87,-86,-84,-83,-82,-80,-79,-77,-76,-75,-73,-72,-70,-69,-68,-66,-65,-63,-62,-61,-59,-58,-56,-55,-53,-52,-51,-49,-48,-46,-45,-44,-42,-41,-39,-38,-37,-35,-34,-32,-31,-30,-28,-27,-25,-24,-23,-21,-20,-18,-17,-15,-14,-13,-11,-10,-8,-7,-6,-4,-3,-1,0,1,3,4,6,7,8,10,11,13,14,15,17,18,20,21,23,24,25,27,28,30,31,32,34,35,37,38,39,41,42,44,45,46,48,49,51,52,53,55,56,58,59,61,62,63,65,66,68,69,70,72,73,75,76,77,79,80,82,83,84,86,87,89,90,91,93,94,96,97,99,100,101,103,104,106,107,108,110,111,113,114,115,117,118,120,121,122,124,125,127,128,129,131,132,134,135,137,138,139,141,142,144,145,146,148,149,151,152,153,155,156,158,159,160,162,163,165,166,167,169,170,172,173,175,176,177,179};const int guarrxyp[]={-44,-44,-44,-43,-43,-42,-42,-42,-41,-41,-41,-40,-40,-40,-39,-39,-39,-38,-38,-38,-37,-37,-37,-36,-36,-36,-35,-35,-35,-34,-34,-34,-33,-33,-32,-32,-32,-31,-31,-31,-30,-30,-30,-29,-29,-29,-28,-28,-28,-27,-27,-27,-26,-26,-26,-25,-25,-25,-24,-24,-23,-23,-23,-22,-22,-22,-21,-21,-21,-20,-20,-20,-19,-19,-19,-18,-18,-18,-17,-17,-17,-16,-16,-16,-15,-15,-15,-14,-14,-13,-13,-13,-12,-12,-12,-11,-11,-11,-10,-10,-10,-9,-9,-9,-8,-8,-8,-7,-7,-7,-6,-6,-6,-5,-5,-4,-4,-4,-3,-3,-3,-2,-2,-2,-1,-1,-1,0,0,0,1,1,1,2,2,2,3,3,3,4,4,4,5,5,6,6,6,7,7,7,8,8,8,9,9,9,10,10,10,11,11,11,12,12,12,13,13,13,14,14,15,15,15,16,16,16,17,17,17,18,18,18,19,19,19,20,20,20,21,21,21,22,22,22,23,23,23,24,24,25,25,25,26,26,26,27,27,27,28,28,28,29,29,29,30,30,30,31,31,31,32,32,32,33,33,34,34,34,35,35,35,36,36,36,37,37,37,38,38,38,39,39,39,40,40,40,41,41,41,42,42,42,43,43,44,44};const int gvarrxyp[]={-92,-91,-90,-90,-89,-88,-87,-87,-86,-85,-85,-84,-83,-82,-82,-81,-80,-80,-79,-78,-77,-77,-76,-75,-75,-74,-73,-72,-72,-71,-70,-70,-69,-68,-67,-67,-66,-65,-65,-64,-63,-62,-62,-61,-60,-60,-59,-58,-57,-57,-56,-55,-54,-54,-53,-52,-52,-51,-50,-49,-49,-48,-47,-47,-46,-45,-44,-44,-43,-42,-42,-41,-40,-39,-39,-38,-37,-37,-36,-35,-34,-34,-33,-32,-32,-31,-30,-29,-29,-28,-27,-27,-26,-25,-24,-24,-23,-22,-22,-21,-20,-19,-19,-18,-17,-16,-16,-15,-14,-14,-13,-12,-11,-11,-10,-9,-9,-8,-7,-6,-6,-5,-4,-4,-3,-2,-1,-1,0,1,1,2,3,4,4,5,6,6,7,8,9,9,10,11,11,12,13,14,14,15,16,16,17,18,19,19,20,21,22,22,23,24,24,25,26,27,27,28,29,29,30,31,32,32,33,34,34,35,36,37,37,38,39,39,40,41,42,42,43,44,44,45,46,47,47,48,49,49,50,51,52,52,53,54,54,55,56,57,57,58,59,60,60,61,62,62,63,64,65,65,66,67,67,68,69,70,70,71,72,72,73,74,75,75,76,77,77,78,79,80,80,81,82,82,83,84,85,85,86,87,87,88,89,90,90,91};const int buarrxyp[]={-228,-226,-224,-222,-221,-219,-217,-215,-213,-212,-210,-208,-206,-205,-203,-201,-199,-197,-196,-194,-192,-190,-189,-187,-185,-183,-181,-180,-178,-176,-174,-173,-171,-169,-167,-165,-164,-162,-160,-158,-157,-155,-153,-151,-149,-148,-146,-144,-142,-141,-139,-137,-135,-133,-132,-130,-128,-126,-125,-123,-121,-119,-117,-116,-114,-112,-110,-109,-107,-105,-103,-101,-100,-98,-96,-94,-93,-91,-89,-87,-85,-84,-82,-80,-78,-76,-75,-73,-71,-69,-68,-66,-64,-62,-60,-59,-57,-55,-53,-52,-50,-48,-46,-44,-43,-41,-39,-37,-36,-34,-32,-30,-28,-27,-25,-23,-21,-20,-18,-16,-14,-12,-11,-9,-7,-5,-4,-2,0,2,4,5,7,9,11,12,14,16,18,20,21,23,25,27,28,30,32,34,36,37,39,41,43,44,46,48,50,52,53,55,57,59,60,62,64,66,68,69,71,73,75,76,78,80,82,84,85,87,89,91,93,94,96,98,100,101,103,105,107,109,110,112,114,116,117,119,121,123,125,126,128,130,132,133,135,137,139,141,142,144,146,148,149,151,153,155,157,158,160,162,164,165,167,169,171,173,174,176,178,180,181,183,185,187,189,190,192,194,196,197,199,201,203,205,206,208,210,212,213,215,217,219,221,222,224,226};#endif /* BMP_H_ */此代码在PC机上可以正常显示，但下到开发板老是出现VIDIOC_S_FMT failed -1
此错误，
检查 发现是 设置格式错误，百度各种说法，有说是pixelformat格式不对的，但在PC机上却是正常的，不管了，先换换，把VIDIOC_S_FMT 和 VIDIOC_G_FMT 反下，先查询支持什么格式再设置，
更改如下
// 设置视频格式 struct v4l2_format <span style="color:#FF0000;">fmt1</span>,fmt; //fmt1临时查询格式使用 memset(&fmt1, 0, sizeof(fmt1)); memset(&fmt, 0, sizeof(fmt)); fmt1.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;</span> //先获取视频格式 ret = ioctl(fd, VIDIOC_G_FMT, &fmt1); if (ret < 0) { printf("VIDIOC_G_FMT failed (%d)\n", ret); goto __error1; } fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; fmt.fmt.pix.width = VIDEO_WIDTH; fmt.fmt.pix.height = VIDEO_HEIGHT; fmt.fmt.pix.pixelformat = fmt1.fmt.pix.pixelformat; //把上面查询到地格式赋给要设置的变量 fmt.fmt.pix.field = V4L2_FIELD_INTERLACED; ret = ioctl(fd, VIDIOC_S_FMT, &fmt); if (ret < 0) { printf("VIDIOC_S_FMT failed (%d)\n", ret); goto __error1; }编译在PC上可正常能过，调试信息时： pixelformat: YUYV下到板子上也能正常运行下去了，调试信息：pixelformat: MJPG
输出格式居然不一样。。。。。。
终于知道错误原因了，应该是开发板和电脑上的UVC驱动版本不一样导致输出的支持格式不一。优化下代码，转MJPG格式输出，MJPG保存图片函数：
//保存为图片 test.jpg
int GenJpgFile(VideoBuffer *buffers,const char *filename){
FILE *fp = NULL;
fp = fopen(filename, "w");
if(fp != NULL){
fwrite(buffers->start, 1,buffers->length, fp);
sync();
fclose(fp);
return 1;
}
return 0;
}
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