使用了是中星微的Z301B的USB摄像头,在天嵌的板子上运行的,在网络上搜了好久的资料,自己也做了好就,可是还是不行啊,我是没有ARM基础的,接触linux也就一两个星期多,现在真的是没有一点头绪了,记下来吧,计算下来以后慢慢品尝了~~
一下的程序可以实现图像的采集,可是只能采集一张图片,然后保存为JPG格式的,就算我选择的视频格式为UYVY格式,保存为YUV格式,但是最终文件内部格式还是JPG格式的,因为利用YUV解码器无法查看文件,将后缀改为JPG后可以用图像查看器查看··········现在我知道要在程序中提取出图像的RGB信息,然后进行转换,转换为YUV格式的,但是找了好久,都没有找到相关资料啊··········真的挺郁闷的 ╮(╯▽╰)╭
下面是提取一张图片的程序源代码,已经实现了,但是程序是别人的,我想改改,将图片保存为YUV格式的,或者视频也可以,但是真不知道如何下手了···经过了两个星期的爬滚,还是一无所获~~~~悲剧啊·························
/*arm-linux-gcc -o usbcamera usbcamera.c ; then download the file and put in the /sbin .*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define CAPTURE_FILE "/media/frame.yuv"
#define CLEAR(x) memset (&(x), 0, sizeof (x))
struct buffer {
void * start;
size_t length;
};
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;
static int read_frame (void)
{
struct v4l2_buffer buf;
unsigned int i;
CLEAR (buf);
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
int ff = ioctl (fd, VIDIOC_DQBUF, &buf);
if(ff<0)
printf("failture\n");
assert (buf.index < n_buffers);
printf ("buf.index dq is %d,\n",buf.index);
fwrite(buffers[buf.index].start, buffers[buf.index].length, 1, file_fd);
///////////////////////
FILE *fp = fopen(CAPTURE_FILE, "w+");
if (fp < 0) {
printf("open frame data file failed\n");
return -1;
}
fwrite(buffers[buf.index].start, 1, buffers[buf.index].length, fp);
fclose(fp);
printf("Capture one frame saved in %s\n", CAPTURE_FILE);
////////////////////
ff=ioctl (fd, VIDIOC_QBUF, &buf);
if(ff<0)
printf("failture VIDIOC_QBUF\n");
return 1;
}
int main (int argc,char ** argv)
{
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");
// 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: %08X\n", cap.version);
printf(" capabilities: %08X\n", cap.capabilities);
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_UYVY;//V4L2_PIX_FMT_JPEG;
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 = 4;//1
req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_MMAP;
ff = ioctl (fd, VIDIOC_REQBUFS, &req);
if(ff<0)
printf("failture VIDIOC_REQBUFS\n");
if (req.count < 1)
printf("Insufficient buffer memory\n");
buffers = (struct buffer*)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);
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 (;;)
{
fd_set fds;
struct timeval tv;
int r;
FD_ZERO (&fds);
FD_SET (fd, &fds);
tv.tv_sec = 2;
tv.tv_usec = 0;
r = select (fd + 1, &fds, NULL, NULL, &tv);
if (-1 == r)
{ if (EINTR == errno)
continue;
printf ("select err\n");
}
if (0 == r)
{
fprintf (stderr, "select timeout\n");
exit (EXIT_FAILURE);
}
if (read_frame ())
break;
}
unmap:
for (i = 0; i < n_buffers; ++i)
if (-1 == munmap (buffers->start, buffers->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);
exit (EXIT_SUCCESS);
return 0;
}