YUYV摄像头采集jpeg格式图片

最新推荐文章于 2024-01-13 09:12:38 发布

driverSir

最新推荐文章于 2024-01-13 09:12:38 发布

阅读量1.4w

点赞数 1

分类专栏： linux_application

本文链接：https://blog.youkuaiyun.com/weed_hz/article/details/8939830

版权

linux_application 专栏收录该内容

41 篇文章

订阅专栏

PC系统：ubuntu10.04
gcc版本：4.5.1
视频协议：V4L2
jpeg压缩库：libjpeg
以上都是开源的，下载安装教程很多，不再赘述

说明：（1）由于libjpeg库的例程中，输入的是RGB24格式的图像，而摄像头只能采集YUYV（YUV：422）格式数据，所以，程序中，有YUYV转换为RGB24的过程，再输入libjpeg中
         （2）关于yuyv与rgb24的格式，网上资料很多，自行查阅资料
         （3）libjpeg库的输出只能是一个文件，如需将输出到内存中，需要修改libjpeg（这个还不会）

程序如下：

#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 <sys/mman.h>
#include <linux/types.h>
#include <linux/videodev2.h>
#include <setjmp.h>
#include "jpeglib.h"
 
//#include "v4l2grab.h"

typedef int BOOL;

#define  TRUE    1
#define  FALSE    0

#define FILE_VIDEO     "/dev/video0"
//#define BMP          "image_bmp.bmp"
#define YUV        "image_yuv.yuv"
#define JPEG        "image_jpeg.jpg"

#define  IMAGEWIDTH    320
#define  IMAGEHEIGHT   240

static   int      fd;
static   struct   v4l2_capability   cap;
struct v4l2_fmtdesc fmtdesc;
struct v4l2_format fmt,fmtack;
struct v4l2_streamparm setfps;  
struct v4l2_requestbuffers req;
struct v4l2_buffer buf;
enum v4l2_buf_type type;
unsigned char frame_buffer[IMAGEWIDTH*IMAGEHEIGHT*3];


struct buffer
{
    void * start;
    unsigned int length;
} * buffers;
 
int init_v4l2(void)
{
    int i;
    int ret = 0;
    
    //opendev
    if ((fd = open(FILE_VIDEO, O_RDWR)) == -1) 
    {
        printf("Error opening V4L interface\n");
        return (FALSE);
    }

    //query cap
    if (ioctl(fd, VIDIOC_QUERYCAP, &cap) == -1) 
    {
        printf("Error opening device %s: unable to query device.\n",FILE_VIDEO);
        return (FALSE);
    }
    else
    {
         printf("driver:\t\t%s\n",cap.driver);
         printf("card:\t\t%s\n",cap.card);
         printf("bus_info:\t%s\n",cap.bus_info);
         printf("version:\t%d\n",cap.version);
         printf("capabilities:\t%x\n",cap.capabilities);
         
         if ((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == V4L2_CAP_VIDEO_CAPTURE) 
         {
            printf("Device %s: supports capture.\n",FILE_VIDEO);
        }

        if ((cap.capabilities & V4L2_CAP_STREAMING) == V4L2_CAP_STREAMING) 
        {
            printf("Device %s: supports streaming.\n",FILE_VIDEO);
        }
    } 
    
    //emu all support fmt
    fmtdesc.index=0;
    fmtdesc.type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
    printf("Support format:\n");
    while(ioctl(fd,VIDIOC_ENUM_FMT,&fmtdesc)!=-1)
    {
        printf("\t%d.%s\n",fmtdesc.index+1,fmtdesc.description);
        fmtdesc.index++;
    }
    
    //set fmt
        fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
    fmt.fmt.pix.height = IMAGEHEIGHT;
    fmt.fmt.pix.width = IMAGEWIDTH;
    fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
    
    if(ioctl(fd, VIDIOC_S_FMT, &fmt) == -1)
    {
        printf("Unable to set format\n");
        return FALSE;
    }     
    if(ioctl(fd, VIDIOC_G_FMT, &fmt) == -1)
    {
        printf("Unable to get format\n");
        return FALSE;
    } 
    {
         printf("fmt.type:\t\t%d\n",fmt.type);
         printf("pix.pixelformat:\t%c%c%c%c\n",fmt.fmt.pix.pixelformat & 0xFF, (fmt.fmt.pix.pixelformat >> 8) & 0xFF,(fmt.fmt.pix.pixelformat >> 16) & 0xFF, (fmt.fmt.pix.pixelformat >> 24) & 0xFF);
         printf("pix.height:\t\t%d\n",fmt.fmt.pix.height);
         printf("pix.width:\t\t%d\n",fmt.fmt.pix.width);
         printf("pix.field:\t\t%d\n",fmt.fmt.pix.field);
    }
    //set fps
    setfps.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    setfps.parm.capture.timeperframe.numerator = 10;
    setfps.parm.capture.timeperframe.denominator = 10;
    
    printf("init %s \t[OK]\n",FILE_VIDEO);
        
    return TRUE;
}

int v4l2_grab(void)
{
    unsigned int n_buffers;
    
    //request for 4 buffers 
    req.count=4;
    req.type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
    req.memory=V4L2_MEMORY_MMAP;
    if(ioctl(fd,VIDIOC_REQBUFS,&req)==-1)
    {
        printf("request for buffers error\n");
    }

    //mmap for buffers
    buffers = malloc(req.count*sizeof (*buffers));
    if (!buffers) 
    {
        printf ("Out of memory\n");
        return(FALSE);
    }
    
    for (n_buffers = 0; n_buffers < req.count; n_buffers++) 
    {
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_MMAP;
        buf.index = n_buffers;
        //query buffers
        if (ioctl (fd, VIDIOC_QUERYBUF, &buf) == -1)
        {
            printf("query buffer error\n");
            return(FALSE);
        }

        buffers[n_buffers].length = buf.length;
        //map
        buffers[n_buffers].start = mmap(NULL,buf.length,PROT_READ |PROT_WRITE, MAP_SHARED, fd, buf.m.offset);
        if (buffers[n_buffers].start == MAP_FAILED)
        {
            printf("buffer map error\n");
            return(FALSE);
        }
    }
        
    //queue
    for (n_buffers = 0; n_buffers < req.count; n_buffers++)
    {
        buf.index = n_buffers;
        ioctl(fd, VIDIOC_QBUF, &buf);
    } 
    
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    ioctl (fd, VIDIOC_STREAMON, &type);
    
    ioctl(fd, VIDIOC_DQBUF, &buf);

    printf("grab yuyv OK\n");
    return(TRUE);
}


int yuyv_2_rgb888(void)
{
    int           i,j;
    unsigned char y1,y2,u,v;
    int r1,g1,b1,r2,g2,b2;
    char * pointer;

    pointer = buffers[0].start;

    for(i=0;i<IMAGEHEIGHT;i++)
    {
    for(j=0;j<IMAGEWIDTH/2;j++)//每次取4个字节，也就是两个像素点，转换rgb，6个字节，还是两个像素点
    {
    y1 = *( pointer + (i*IMAGEWIDTH/2+j)*4);     
    u  = *( pointer + (i*IMAGEWIDTH/2+j)*4 + 1);
    y2 = *( pointer + (i*IMAGEWIDTH/2+j)*4 + 2);
    v  = *( pointer + (i*IMAGEWIDTH/2+j)*4 + 3);

    r1 = y1 + 1.042*(v-128);
    g1 = y1 - 0.34414*(u-128) - 0.71414*(v-128);
    b1 = y1 + 1.772*(u-128);

    r2 = y2 + 1.042*(v-128);
    g2 = y2 - 0.34414*(u-128) - 0.71414*(v-128);
    b2 = y2 + 1.772*(u-128);

    if(r1>255)
    r1 = 255;
    else if(r1<0)
    r1 = 0;

    if(b1>255)
    b1 = 255;
    else if(b1<0)
    b1 = 0;    

    if(g1>255)
    g1 = 255;
    else if(g1<0)
    g1 = 0;    

    if(r2>255)
    r2 = 255;
    else if(r2<0)
    r2 = 0;

    if(b2>255)
    b2 = 255;
    else if(b2<0)
    b2 = 0;    

    if(g2>255)
    g2 = 255;
    else if(g2<0)
    g2 = 0;        

    *(frame_buffer + (i*IMAGEWIDTH/2+j)*6    ) = (unsigned char)b1;
    *(frame_buffer + (i*IMAGEWIDTH/2+j)*6 + 1) = (unsigned char)g1;
    *(frame_buffer + (i*IMAGEWIDTH/2+j)*6 + 2) = (unsigned char)r1;
    *(frame_buffer + (i*IMAGEWIDTH/2+j)*6 + 3) = (unsigned char)b2;
    *(frame_buffer + (i*IMAGEWIDTH/2+j)*6 + 4) = (unsigned char)g2;
    *(frame_buffer + (i*IMAGEWIDTH/2+j)*6 + 5) = (unsigned char)r2;
    }
    }
    printf("change to RGB OK \n");
}

BOOL encode_jpeg(char *lpbuf,int width,int height)
{
    struct jpeg_compress_struct cinfo ;
    struct jpeg_error_mgr jerr ;
    JSAMPROW  row_pointer[1] ;
    int row_stride ;
    char *buf=NULL ;
    int x ;

    FILE *fptr_jpg = fopen (JPEG,"wb");//注意这里为什么用fopen而不用open
    if(fptr_jpg==NULL)
    {
    printf("Encoder:open file failed!/n") ;
     return FALSE;
    }

    cinfo.err = jpeg_std_error(&jerr);
    jpeg_create_compress(&cinfo);
    jpeg_stdio_dest(&cinfo, fptr_jpg);

    cinfo.image_width = width;
    cinfo.image_height = height;
    cinfo.input_components = 3;
    cinfo.in_color_space = JCS_RGB;

    jpeg_set_defaults(&cinfo);


    jpeg_set_quality(&cinfo, 80,TRUE);


    jpeg_start_compress(&cinfo, TRUE);

    row_stride = width * 3;
    buf=malloc(row_stride) ;
    row_pointer[0] = buf;
    while (cinfo.next_scanline < height)
    {
     for (x = 0; x < row_stride; x+=3)
    {

    buf[x]   = lpbuf[x];
    buf[x+1] = lpbuf[x+1];
    buf[x+2] = lpbuf[x+2];

    }
    jpeg_write_scanlines (&cinfo, row_pointer, 1);//critical
    lpbuf += row_stride;
    }

    jpeg_finish_compress(&cinfo);
    fclose(fptr_jpg);
    jpeg_destroy_compress(&cinfo);
    free(buf) ;
    return TRUE ;

}  

int close_v4l2(void)
{
     if(fd != -1) 
     {
         close(fd);
         return (TRUE);
     }
     return (FALSE);
}


int main(void)
{
    FILE * fp2;

    if(init_v4l2() == FALSE) 
    {
    return(FALSE);
    }
    v4l2_grab();

    yuyv_2_rgb888();                  //yuyv to RGB24

    encode_jpeg(frame_buffer,IMAGEWIDTH,IMAGEHEIGHT); //RGB24 to Jpeg
    printf("save "JPEG"OK\n");

    close_v4l2();

    return(TRUE);
}