把YUYV转化为jpg格式（改进v4l2的应用程序编写）

参见：linux下usb摄像头采集的YUYV格式转换成JPEG格式的图片

只是最后图像不清晰，尚不清楚原因

1.要用jpeg库编译，所以要先编译jpegsrc.v6b.tar.gz，

$ cd jpeg-6b

 $ ./configure --prefix=/work/tools/gcc-3.4.5-glibc-2.3.6/arm-linux

 $ make

 $ make install

2.然后编译video2_jpeg.c

>arm-linux-gcc -o video2_jpeg video2_jpeg.c -I/work/tools/gcc -I/work/tools/gcc-3.4.5-glibc-2.3.6/arm-linux/include -L//work/tools/gcc-3.4.5-glibc-2.3.6/arm-linux/lib -ljpeg

源码video2_jpeg.c如下：

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

 

#define OUTPUT_BUF_SIZE 4096

#define CLEAR(x) memset(&(x), 0, sizeof(x))

#define WIDTH 320

#define HEIGHT 240

 

struct buffer {

 void *start;

 size_t length;

};

 

typedef struct {

struct jpeg_destination_mgr pub;

 

JOCTET * buffer;

 

unsigned char *outbuffer;

int outbuffer_size;

unsigned char *outbuffer_cursor;

int *written;

 

}mjpg_destination_mgr;

 

typedef mjpg_destination_mgr *mjpg_dest_ptr;

 

static char * dev_name= "/dev/video0";

static int fd= -1;
struct buffer * buffers = NULL;
static unsigned int n_buffers = 0;
FILE *file_fd;

static unsigned long file_length;

static unsigned char *file_name;

 

METHODDEF(void) init_destination(j_compress_ptr cinfo) {

mjpg_dest_ptr dest =(mjpg_dest_ptr) cinfo->dest;

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;

}

 

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;

}

 

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;

}

 

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;

}

 

//......YUYV.....JPEG..

int compress_yuyv_to_jpeg(unsigned char *buf, unsigned char *buffer, int size, 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;

//int count = 0;

//printf("%s\n", buf);

line_buffer = calloc(WIDTH * 3, 1);

yuyv = buf;
printf("compress start...\n");

cinfo.err = jpeg_std_error(&jerr);

jpeg_create_compress(&cinfo);

/* jpeg_stdio_dest(&cinfo, file); */

dest_buffer(&cinfo, 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);

 

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;

}

}

 

row_pointer[0] = line_buffer;

jpeg_write_scanlines(&cinfo, row_pointer, 1);

}

 

jpeg_finish_compress(&cinfo);

jpeg_destroy_compress(&cinfo);

 

free(line_buffer);

return(written);

}

 

//读取一帧的内容

static int read_frame(void)

{

 struct v4l2_buffer buf;

 int ret;

 unsigned int i;

 CLEAR(buf);

 buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

 buf.memory = V4L2_MEMORY_MMAP;

 int ff = ioctl(fd, VIDIOC_DQBUF, &buf); ///出列采集的帧缓冲

 if(ff<0)

 printf("failture\n");

 unsigned char src[buf.length+1];

 unsigned char dest[buf.length+1];

 assert(buf.index < n_buffers);

printf("buf.index dq is %d,\n",buf.index);

 

 memcpy(src, buffers[buf.index].start, buf.length);

 ret = compress_yuyv_to_jpeg(src, dest,(WIDTH * HEIGHT), 80);//....

 fwrite(dest, ret, 1, file_fd);//........

 ff=ioctl(fd, VIDIOC_QBUF, &buf); //....

 if(ff<0)

 printf("failture VIDIOC_QBUF\n");

 return 1;

}

 

//上面四个函数都是给下面get_picture用的

//get_picture->read_frame->compress_yuyv_to_jpeg->dest_buffer

//在dest_buffer（）函数中：设置

//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;

int get_picture()

{

 struct v4l2_capability cap;

 struct v4l2_format fmt;

 unsigned int i;

 enum v4l2_buf_type type;

 

 file_fd = fopen("test-mmap.jpg", "w");

 fd = open(dev_name, O_RDWR | O_NONBLOCK, 0);

 int ff=ioctl(fd, VIDIOC_QUERYCAP, &cap);//.......

 

 if(ff<0)

 printf("failture VIDIOC_QUERYCAP\n");

 

 struct v4l2_fmtdesc fmt1;

 int ret;

 

 memset(&fmt1, 0, sizeof(fmt1));

fmt1.index = 0;

fmt1.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

while((ret = ioctl(fd, VIDIOC_ENUM_FMT, &fmt1)) == 0) //...........

{

fmt1.index++;

printf("{ pixelformat = '%c%c%c%c', description = '%s' }\n",

fmt1.pixelformat & 0xFF,(fmt1.pixelformat >> 8) & 0xFF,

 (fmt1.pixelformat >> 16) & 0xFF,(fmt1.pixelformat >> 24) & 0xFF,

 fmt1.description);

}

 CLEAR(fmt);

 fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

 fmt.fmt.pix.width = 640;

 fmt.fmt.pix.height= 480;

 fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;

 fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;

 

 ff = ioctl(fd, VIDIOC_S_FMT, &fmt); //......

 if(ff<0)

 printf("failture VIDIOC_S_FMT\n");

 

 file_length = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height; //......

 struct v4l2_requestbuffers req;

 CLEAR(req);

 req.count = 1;

 req.type= V4L2_BUF_TYPE_VIDEO_CAPTURE;

 req.memory= V4L2_MEMORY_MMAP;

 

 ioctl(fd, VIDIOC_REQBUFS, &req);//.....count......

 if(ff<0)

printf("failture VIDIOC_REQBUFS\n");

 if(req.count < 1)

printf("Insufficient buffer memory\n");

buffers = calloc(req.count, sizeof(*buffers));
 
for(n_buffers = 0; n_buffers < req.count; ++n_buffers)
{

struct v4l2_buffer buf;

CLEAR(buf);

buf.type= V4L2_BUF_TYPE_VIDEO_CAPTURE;

buf.memory= V4L2_MEMORY_MMAP;

buf.index = n_buffers;

 if(-1 == ioctl(fd, VIDIOC_QUERYBUF, &buf)) //......

 printf("VIDIOC_QUERYBUF error\n");

 buffers[n_buffers].length = buf.length;

buffers[n_buffers].start=mmap(NULL,buf.length,PROT_READ|PROT_WRITE,MAP_SHARED,fd,buf.m.offset); //..mmap......

 if(MAP_FAILED == buffers[n_buffers].start)

 printf("mmap failed\n");

 }

 

 for(i = 0; i < n_buffers; ++i)

 {

struct v4l2_buffer buf;

CLEAR(buf);

buf.type= V4L2_BUF_TYPE_VIDEO_CAPTURE;

buf.memory= V4L2_MEMORY_MMAP;

buf.index = i;

if(-1 == ioctl(fd, VIDIOC_QBUF, &buf))//..........

printf("VIDIOC_QBUF failed\n");

 }

 type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

 if(-1 == ioctl(fd, VIDIOC_STREAMON, &type)) //........

 printf("VIDIOC_STREAMON failed\n");

 

 for(;;) //........IO

 {

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);//......(...........tv...

if(-1 == r)

{

 if(EINTR == errno)
continue;
printf("select err\n");
}

if(0 == r)
{
fprintf(stderr, "select timeout\n");
return -1;
}

 

if(read_frame())//.......read_frame..
 break;
 }

 for(i = 0; i < n_buffers; ++i)
if(-1 == munmap(buffers[i].start, buffers[i].length))
 printf("munmap error");
 type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

if(-1 == ioctl(fd, VIDIOC_STREAMOFF, &type))
printf("VIDIOC_STREAMOFF");
close(fd);
fclose(file_fd);
return 0;
}

//main函数中调用这个函数就可以了

int main(){
    get_picture();
 
    return 0;
    }