一、环境介绍
操作系统：ubuntu18.04 X64位 和 嵌入式Linux操作(ARM)
二、功能介绍
通过Linux下标准V4L2框架采集摄像头的数据，通过jpeglib库连续编码为JPG格式图片存放到本地。
三、安装jpeglib库
jpeglib下载地址：
http://www.ijg.org/
wbyq@wbyq:~/work_pc$ tar xvf /mnt/hgfs/linux-share-dir/jpegsrc.v9d.tar.gz
wbyq@wbyq:~/work_pc$ cd jpeg-9d/
wbyq@wbyq:~/work_pc/jpeg-9d$ ./configure
wbyq@wbyq:~/work_pc/jpeg-9d$ make
wbyq@wbyq:~/work_pc/jpeg-9d$ sudo make install
[sudo] wbyq 的密码：
make[1]: 进入目录“/home/wbyq/work_pc/jpeg-9d”
/bin/mkdir -p '/usr/local/lib'
/bin/bash ./libtool --mode=install /usr/bin/install -c libjpeg.la '/usr/local/lib'
libtool: install: /usr/bin/install -c .libs/libjpeg.so.9.4.0 /usr/local/lib/libjpeg.so.9.4.0
libtool: install: (cd /usr/local/lib && { ln -s -f libjpeg.so.9.4.0 libjpeg.so.9 || { rm -f libjpeg.so.9 && ln -s libjpeg.so.9.4.0 libjpeg.so.9; }; })
libtool: install: (cd /usr/local/lib && { ln -s -f libjpeg.so.9.4.0 libjpeg.so || { rm -f libjpeg.so && ln -s libjpeg.so.9.4.0 libjpeg.so; }; })
libtool: install: /usr/bin/install -c .libs/libjpeg.lai /usr/local/lib/libjpeg.la
libtool: install: /usr/bin/install -c .libs/libjpeg.a /usr/local/lib/libjpeg.a
libtool: install: chmod 644 /usr/local/lib/libjpeg.a
libtool: install: ranlib /usr/local/lib/libjpeg.a
libtool: finish: PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin:/sbin" ldconfig -n /usr/local/lib
----------------------------------------------------------------------
Libraries have been installed in:
/usr/local/lib
If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the '-LLIBDIR'
flag during linking and do at least one of the following:
- add LIBDIR to the 'LD_LIBRARY_PATH' environment variable
during execution
- add LIBDIR to the 'LD_RUN_PATH' environment variable
during linking
- use the '-Wl,-rpath -Wl,LIBDIR' linker flag
- have your system administrator add LIBDIR to '/etc/ld.so.conf'
See any operating system documentation about shared libraries for
more information, such as the ld(1) and ld.so(8) manual pages.
----------------------------------------------------------------------
/bin/mkdir -p '/usr/local/bin'
/bin/bash ./libtool --mode=install /usr/bin/install -c cjpeg djpeg jpegtran rdjpgcom wrjpgcom '/usr/local/bin'
libtool: install: /usr/bin/install -c .libs/cjpeg /usr/local/bin/cjpeg
libtool: install: /usr/bin/install -c .libs/djpeg /usr/local/bin/djpeg
libtool: install: /usr/bin/install -c .libs/jpegtran /usr/local/bin/jpegtran
libtool: install: /usr/bin/install -c rdjpgcom /usr/local/bin/rdjpgcom
libtool: install: /usr/bin/install -c wrjpgcom /usr/local/bin/wrjpgcom
/bin/bash /home/wbyq/work_pc/jpeg-9d/install-sh -d /usr/local/include
/usr/bin/install -c -m 644 jconfig.h /usr/local/include/jconfig.h
/bin/mkdir -p '/usr/local/include'
/usr/bin/install -c -m 644 jerror.h jmorecfg.h jpeglib.h '/usr/local/include'
/bin/mkdir -p '/usr/local/share/man/man1'
/usr/bin/install -c -m 644 cjpeg.1 djpeg.1 jpegtran.1 rdjpgcom.1 wrjpgcom.1 '/usr/local/share/man/man1'
/bin/mkdir -p '/usr/local/lib/pkgconfig'
/usr/bin/install -c -m 644 libjpeg.pc '/usr/local/lib/pkgconfig'
make[1]: 离开目录“/home/wbyq/work_pc/jpeg-9d” 默认的安装路径在/usr/local/lib/ 目录下。
如果是编译给嵌入式Linux平台使用可以按照下面方法配置：
./configure --prefix=/usr/local/lib CC=arm-linux-gcc --host=arm-linux --enable-shared --enable-static
四、核心代码
video_app.c : 摄像头采集的主要代码
#include <stdio.h>
#include <sys/ioctl.h>
#include <linux/videodev2.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <poll.h>
#include <stdlib.h>
#include "yuv_to_jpeg.h"
int image_height;
int image_width;
unsigned char *image_buffer[4];
int uvc_video_fd;
/*
函数功能: 摄像头设备初始化
*/
int VideoDeviceInit(char *DEVICE_NAME)
{
/*1. 打开摄像头设备*/
uvc_video_fd=open(DEVICE_NAME,O_RDWR);
if(uvc_video_fd<0)
{
printf("%s 摄像头设备打开失败!\n",DEVICE_NAME);
return -1;
}
else
{
printf("摄像头打开成功.\n");
}
/*2 设置摄像头的属性*/
struct v4l2_format format;
/*2.1 查询当前摄像头支持的格式*/
//当前视频设备支持的视频图像格式
struct v4l2_fmtdesc fmt;
memset(&fmt,0,sizeof(fmt));
fmt.index = 0;
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
printf("当前摄像头支持输出的图像格式如下:\n");
while(ioctl(uvc_video_fd,VIDIOC_ENUM_FMT,&fmt) == 0)
{
fmt.index ++ ;
printf("<'%c%c%c%c'--'%s'>\n",
fmt.pixelformat & 0xff,(fmt.pixelformat >> 8)&0xff,
(fmt.pixelformat >> 16) & 0xff,(fmt.pixelformat >> 24)&0xff,
fmt.description);
}
/*2.2 设置摄像头输出的宽度高度与颜色格式(V4L2_PIX_FMT_YUYV)*/
memset(&format,0,sizeof(struct v4l2_format));
format.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*表示视频捕获设备*/
format.fmt.pix.width=2000; /*预设的宽度*/
format.fmt.pix.height=2000; /*预设的高度*/
format.fmt.pix.pixelformat=V4L2_PIX_FMT_YUYV; /*预设的格式*/
format.fmt.pix.field=V4L2_FIELD_ANY; /*系统自动设置: 帧属性*/
if(ioctl(uvc_video_fd,VIDIOC_S_FMT,&format)) /*设置摄像头的属性*/
{
printf("摄像头格式设置失败!\n");
return -2;
}
image_width=format.fmt.pix.width;
image_height=format.fmt.pix.height;
printf("摄像头实际输出的图像尺寸:x=%d,y=%d\n",format.fmt.pix.width,format.fmt.pix.height);
if(format.fmt.pix.pixelformat==V4L2_PIX_FMT_YUYV)
{
printf("当前摄像头支持YUV格式图像输出!\n");
}
else
{
printf("当前摄像头不支持YUV格式图像输出!\n");
return -3;
}
/*2.3 设置摄像头采集的帧率*/
struct v4l2_streamparm streamparm;
streamparm.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*表示视频捕获设备*/
streamparm.parm.capture.timeperframe.numerator=1;
streamparm.parm.capture.timeperframe.denominator=30;
printf("设置当前摄像头采集帧率: %d秒%d帧\n",streamparm.parm.capture.timeperframe.numerator,streamparm.parm.capture.timeperframe.denominator);
if(ioctl(uvc_video_fd,VIDIOC_S_PARM,&streamparm)) /*设置摄像头的帧率*/
{
printf("设置摄像头采集的帧率失败!\n");
return -3;
}
if(ioctl(uvc_video_fd,VIDIOC_S_PARM,&streamparm)) /*获取摄像头的帧率*/
{
printf("获取摄像头采集的帧率失败!\n");
return -3;
}
printf("当前摄像头实际采集帧率: %d秒%d帧\n",streamparm.parm.capture.timeperframe.numerator,streamparm.parm.capture.timeperframe.denominator);
/*3. 请求缓冲区: 申请摄像头数据采集的缓冲区*/
struct v4l2_requestbuffers req_buff;
memset(&req_buff,0,sizeof(struct v4l2_requestbuffers));
req_buff.count=4; /*预设要申请4个缓冲区*/
req_buff.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/
req_buff.memory=V4L2_MEMORY_MMAP; /*支持mmap内存映射*/
if(ioctl(uvc_video_fd,VIDIOC_REQBUFS,&req_buff)) /*申请缓冲区*/
{
printf("申请摄像头数据采集的缓冲区失败!\n");
return -4;
}
printf("摄像头缓冲区申请的数量: %d\n",req_buff.count);
/*4. 获取缓冲区的详细信息: 地址,编号*/
struct v4l2_buffer buff_info;
memset(&buff_info,0,sizeof(struct v4l2_buffer));
int i;
for(i=0;i<req_buff.count;i++)
{
buff_info.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/
buff_info.memory=V4L2_MEMORY_MMAP; /*支持mmap内存映射*/
if(ioctl(uvc_video_fd,VIDIOC_QUERYBUF,&buff_info)) /*获取缓冲区的详细信息*/
{
printf("获取缓冲区的详细信息失败!\n");
return -5;
}
/*根据摄像头申请缓冲区信息: 使用mmap函数将内核的地址映射到进程空间*/
image_buffer[i]=mmap(NULL,buff_info.length,PROT_READ|PROT_WRITE,MAP_SHARED,uvc_video_fd,buff_info.m.offset);
if(image_buffer[i]==NULL)
{
printf("缓冲区映射失败!\n");
return -6;
}
}
/*5. 将缓冲区放入采集队列*/
memset(&buff_info,0,sizeof(struct v4l2_buffer));
for(i=0;i<req_buff.count;i++)
{
buff_info.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/
buff_info.index=i; /*缓冲区的节点编号*/
buff_info.memory=V4L2_MEMORY_MMAP; /*支持mmap内存映射*/
if(ioctl(uvc_video_fd,VIDIOC_QBUF,&buff_info)) /*根据节点编号将缓冲区放入队列*/
{
printf("根据节点编号将缓冲区放入队列失败!\n");
return -7;
}
}
/*6. 启动摄像头数据采集*/
int Type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
if(ioctl(uvc_video_fd,VIDIOC_STREAMON,&Type))
{
printf("启动摄像头数据采集失败!\n");
return -8;
}
return 0;
}
int main(int argc,char **argv)
{
if(argc!=2)
{
printf("./app </dev/videoX>\n");
return 0;
}
int err;
char jpg_file_name[100]; /*存放JPG图片名称*/
int jpg_cnt=0;
FILE *jpg_file;
int jpg_size;
/*1. 初始化摄像头设备*/
err=VideoDeviceInit(argv[1]);
printf("VideoDeviceInit=%d\n",err);
/*2. 循环读取摄像头采集的数据*/
struct pollfd fds;
fds.fd=uvc_video_fd;
fds.events=POLLIN;
/*3. 申请存放JPG的数据空间*/
unsigned char *jpg_p=malloc(image_height*image_width*3);
struct v4l2_buffer video_buffer;
while(1)
{
/*(1)等待摄像头采集数据*/
poll(&fds,1,-1);
/*(2)取出队列里采集完毕的缓冲区*/
video_buffer.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/
video_buffer.memory=V4L2_MEMORY_MMAP;
ioctl(uvc_video_fd,VIDIOC_DQBUF,&video_buffer);
/*(3)处理图像数据*/
printf("image_buffer[%d]=%X\n",video_buffer.index,image_buffer[video_buffer.index]);
/*YUV数据转JPEG格式*/
jpg_size=yuv_to_jpeg(image_width,image_height,image_height*image_width*3,image_buffer[video_buffer.index],jpg_p,80);
sprintf(jpg_file_name,"%d.jpg",jpg_cnt++);
printf("图片名称:%s,字节大小:%d\n",jpg_file_name,jpg_size);
jpg_file=fopen(jpg_file_name,"wb");
fwrite(jpg_p,1,jpg_size,jpg_file);
fclose(jpg_file);
/*(4)将缓冲区再放入队列*/
ioctl(uvc_video_fd,VIDIOC_QBUF,&video_buffer);
}
return 0;
} yuv_to_jpg.c : YUV格式图片转JPG格式图片核心代码
#include "yuv_to_jpeg.h"
#define OUTPUT_BUF_SIZE 4096
typedef struct
{
struct jpeg_destination_mgr pub; /* public fields */
JOCTET * buffer; /* start of buffer */
unsigned char *outbuffer;
int outbuffer_size;
unsigned char *outbuffer_cursor;
int *written;
} mjpg_destination_mgr;
typedef mjpg_destination_mgr *mjpg_dest_ptr;
/******************************************************************************
函数功能: 初始化输出的目的地
******************************************************************************/
METHODDEF(void) init_destination(j_compress_ptr cinfo)
{
mjpg_dest_ptr dest = (mjpg_dest_ptr) cinfo->dest;
/* Allocate the output buffer --- it will be released when done with image */
dest->buffer = (JOCTET *)(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, OUTPUT_BUF_SIZE * sizeof(JOCTET));
*(dest->written) = 0;
dest->pub.next_output_byte = dest->buffer;
dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
}
/******************************************************************************
函数功能: 当jpeg缓冲区填满时调用
******************************************************************************/
METHODDEF(boolean) empty_output_buffer(j_compress_ptr cinfo)
{
mjpg_dest_ptr dest = (mjpg_dest_ptr) cinfo->dest;
memcpy(dest->outbuffer_cursor, dest->buffer, OUTPUT_BUF_SIZE);
dest->outbuffer_cursor += OUTPUT_BUF_SIZE;
*(dest->written) += OUTPUT_BUF_SIZE;
dest->pub.next_output_byte = dest->buffer;
dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
return TRUE;
}
/******************************************************************************
函数功能:在写入所有数据之后，由jpeg_finish_compress调用。通常需要刷新缓冲区。
******************************************************************************/
METHODDEF(void) term_destination(j_compress_ptr cinfo)
{
mjpg_dest_ptr dest = (mjpg_dest_ptr) cinfo->dest;
size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
/* Write any data remaining in the buffer */
memcpy(dest->outbuffer_cursor, dest->buffer, datacount);
dest->outbuffer_cursor += datacount;
*(dest->written) += datacount;
}
/******************************************************************************
功能描述：初始化输出流
函数参数:
j_compress_ptr cinfo :保存JPG图像压缩信息的结构体地址
unsigned char *buffer :存放压缩之后的JPG图片的缓冲区首地址
int size :源图像字节总大小
int *written :存放压缩之后的JPG图像字节大小
******************************************************************************/
GLOBAL(void) dest_buffer(j_compress_ptr cinfo, unsigned char *buffer, int size, int *written)
{
mjpg_dest_ptr dest;
if (cinfo->dest == NULL) {
cinfo->dest = (struct jpeg_destination_mgr *)(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, sizeof(mjpg_destination_mgr));
}
dest = (mjpg_dest_ptr) cinfo->dest;
dest->pub.init_destination = init_destination;
dest->pub.empty_output_buffer = empty_output_buffer;
dest->pub.term_destination = term_destination;
dest->outbuffer = buffer;
dest->outbuffer_size = size;
dest->outbuffer_cursor = buffer;
dest->written = written;
}
/************************************************
功能描述：将YUV格式的数据转为JPG格式。
函数参数:
int Width 源图像宽度
int Height 源图像高度
int size 源图像字节总大小
unsigned char *yuv_buffer :存放YUV源图像数据缓冲区的首地址
unsigned char *jpg_buffer :存放转换之后的JPG格式数据缓冲区首地址
int quality :jpg图像的压缩质量(值越大质量越好,图片就越清晰,占用的内存也就越大)
一般取值范围是: 10 ~ 100 。 填10图片就有些模糊了，一般的JPG图片都是质量都是80。
返回值：压缩之后的JPG图像大小
**************************************************************/
int yuv_to_jpeg(int Width,int Height,int size,unsigned char *yuv_buffer, unsigned char *jpg_buffer, int quality)
{
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
JSAMPROW row_pointer[1];
unsigned char *line_buffer, *yuyv;
int z;
static int written;
/*1. 解压之前的初始化*/
line_buffer =(unsigned char *)calloc(Width*3,1);
yuyv=yuv_buffer; //得到图像源数据
cinfo.err = jpeg_std_error (&jerr);
jpeg_create_compress (&cinfo);
/* 原版jpeglib库的标准输出初始化函数,只能填文件指针: jpeg_stdio_dest (&cinfo, file); */
/* 修改之后的标准输出初始化函数,将输出指向内存空间*/
dest_buffer(&cinfo, jpg_buffer, size, &written);
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, quality, TRUE);
jpeg_start_compress (&cinfo, TRUE);
/*2. YUV转RGB格式*/
z = 0;
while (cinfo.next_scanline < Height)
{
int x;
unsigned char *ptr = line_buffer;
for (x = 0; x < Width; x++) {
int r, g, b;
int y, u, v;
if (!z)
y = yuyv[0] << 8;
else
y = yuyv[2] << 8;
u = yuyv[1] - 128;
v = yuyv[3] - 128;
r = (y + (359 * v)) >> 8;
g = (y - (88 * u) - (183 * v)) >> 8;
b = (y + (454 * u)) >> 8;
*(ptr++) = (r > 255) ? 255 : ((r < 0) ? 0 : r);
*(ptr++) = (g > 255) ? 255 : ((g < 0) ? 0 : g);
*(ptr++) = (b > 255) ? 255 : ((b < 0) ? 0 : b);
if (z++) {
z = 0;
yuyv += 4;
}
}
/*3.进行JPG图像压缩(一行一行压缩)*/
row_pointer[0] = line_buffer;
jpeg_write_scanlines(&cinfo, row_pointer, 1);
}
/*4. 释放压缩时占用的内存空间*/
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
free (line_buffer);
/*5. 返回压缩之后JPG图片大小*/
return (written);
} yuv_to_jpg.h : YUV转JPG代码的头文件
#ifndef YUC_TO_JPEG_H
#define YUC_TO_JPEG_H
#include <stdio.h>
#include <jpeglib.h>
#include <stdlib.h>
#include <string.h>
int yuv_to_jpeg(int Width,int Height,int size,unsigned char *yuv_buffer, unsigned char *jpg_buffer, int quality);
#endif Makefile 文件代码：
all:
gcc video_app.c yuv_to_jpeg.c -o app -ljpeg 五、编译运行-测试效果
如果运行时提示找不到库，可以先搜索库的路径，将库的路径加入到环境变量里即可：
error while loading shared libraries: libjpeg.so.9: cannot open shared object file: No such file or directory
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c/yuv_save_jpg$ ./app
./app: error while loading shared libraries: libjpeg.so.9: cannot open shared object file: No such file or directory
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c/yuv_save_jpg$ sudo find / -name libjpeg.so.9
find: ‘/run/user/1000/gvfs’: 权限不够
/home/wbyq/work_pc/jpeg-9d/.libs/libjpeg.so.9
/usr/local/lib/libjpeg.so.9
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c/yuv_save_jpg$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib/ 编译程序运行步骤如下：
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c/yuv_save_jpg$ make
gcc video_app.c yuv_to_jpeg.c -o app -ljpeg
video_app.c: In function ‘main’:
video_app.c:190:33: warning: format ‘%X’ expects argument of type ‘unsigned int’, but argument 3 has type ‘unsigned char *’ [-Wformat=]
printf("image_buffer[%d]=%X\n",video_buffer.index,image_buffer[video_buffer.index]);
~^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%hhn
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c/yuv_save_jpg$ ./app
./app: error while loading shared libraries: libjpeg.so.9: cannot open shared object file: No such file or directory
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c/yuv_save_jpg$ sudo find / -name libjpeg.so.9
find: ‘/run/user/1000/gvfs’: 权限不够
/home/wbyq/work_pc/jpeg-9d/.libs/libjpeg.so.9
/usr/local/lib/libjpeg.so.9
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c/yuv_save_jpg$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib/
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c/yuv_save_jpg$ ./app
./app </dev/videoX>
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c/yuv_save_jpg$ ./app /dev/video0
摄像头打开成功.
当前摄像头支持输出的图像格式如下:
<'YUYV'--'YUYV 4:2:2'>
<'MJPG'--'Motion-JPEG'>
摄像头实际输出的图像尺寸:x=1280,y=960
当前摄像头支持YUV格式图像输出!
设置当前摄像头采集帧率: 1秒30帧
当前摄像头实际采集帧率: 2秒15帧
摄像头缓冲区申请的数量: 4
VideoDeviceInit=0
image_buffer[0]=4C129000
图片名称:0.jpg,字节大小:135722
image_buffer[1]=4BED1000
图片名称:1.jpg,字节大小:135722
image_buffer[2]=4BC79000
图片名称:2.jpg,字节大小:135722
image_buffer[3]=4BA21000
图片名称:3.jpg,字节大小:135722
image_buffer[0]=4C129000
图片名称:4.jpg,字节大小:132494
image_buffer[1]=4BED1000
图片名称:5.jpg,字节大小:132494
image_buffer[2]=4BC79000
图片名称:6.jpg,字节大小:132494
image_buffer[3]=4BA21000
图片名称:7.jpg,字节大小:132494
image_buffer[0]=4C129000
图片名称:8.jpg,字节大小:126119
image_buffer[1]=4BED1000
图片名称:9.jpg,字节大小:126119
image_buffer[2]=4BC79000
图片名称:10.jpg,字节大小:126119
image_buffer[3]=4BA21000
图片名称:11.jpg,字节大小:126119 程序停止，可以按下Ctrl+C。
下面图片是采集的效果。