yu he
Newbie level 2
Hi!
I want to display a picture on lcd,I use V4L2(which is one of linux interface) to achieve it,but is still some
problems.I need an example to study.
Here is my C source codes.Thanks for your help.
In this codes,I capture some pictures and it is correct,but displaying these pictures on lcd is wrong.
I want to display a picture on lcd,I use V4L2(which is one of linux interface) to achieve it,but is still some
problems.I need an example to study.
Here is my C source codes.Thanks for your help.
In this codes,I capture some pictures and it is correct,but displaying these pictures on lcd is wrong.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <getopt.h> /* getopt_long() */
#include <fcntl.h> /* low-level i/o */
#include <malloc.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <linux/videodev.h>
#include <asm/types.h> /* for videodev2.h */
#include <linux/videodev2.h>
#include <linux/fb.h>
#define CLEAR(x) memset (&(x), 0, sizeof (x))
static int fd=-1;
static int fb=-1;
static int ret;
FILE *fp;
char *filename = "image.yuv";
static unsigned char *fbmem;
static unsigned int screensize;
static unsigned int fb_width;
static unsigned int fb_height;
static unsigned int fb_depth;
static char *dev_name = NULL;
static unsigned int n_buffers = 0;
static unsigned int width = 720;
static unsigned int height = 480;
struct buffer {
void *start;
size_t length;
};
struct buffer *buffers = NULL;
struct timeval tv0,tv1;
unsigned int timeus=0;
float tm;
static void errno_exit (const char *s)
{
fprintf(stderr, "%s error %d, %s\n", s, errno, strerror(errno));
exit(EXIT_FAILURE);
}
static int xioctl (int fd, int request, void *arg)
{
int r;
do r = ioctl (fd, request, arg);
while (-1 == r && EINTR == errno);
return r;
}
void *fb_mmap(int fb, unsigned int screensize)
{
caddr_t fbmem;
if ((fbmem = mmap(NULL, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fb, 0)) == MAP_FAILED)
{ errno_exit("fb_mmap"); }
return (fbmem);
}
int fb_stat(int fb, int *width, int *height, int *depth)
{
struct fb_fix_screeninfo fix;
if (xioctl(fb, FBIOGET_FSCREENINFO, &fix)) { errno_exit("FBIOGET_FSCREENINFO"); }
printf("********************** fb_fix Information **********************\n");
printf(" Xpanstep: %d\n", fix.xpanstep);
printf(" Line length: %d\n", fix.line_length);
printf(" Physical Address: %x\n", fix.smem_start);
printf(" Buffer Length: %d\n", fix.smem_len);
struct fb_var_screeninfo var;
if (xioctl(fb, FBIOGET_VSCREENINFO, &var)) { errno_exit("FBIOGET_VSCREENINFO"); }
printf("********************** fb_var Information **********************\n");
printf(" xres: %d\n", var.xres);
printf(" yres: %d\n", var.yres);
printf(" bites_per_pixel: %d\n", var.bits_per_pixel);
printf(" memory_picture_width: %d\n", var.width);
printf(" memory_picture_height: %d\n", var.height);
*width = var.xres;
*height = var.yres;
*depth = var.bits_per_pixel;
printf("********************** fb_stat Information **********************\n");
printf(" width = %d\n height = %d\n depth = %d\n",*width,*height,*depth);
return 0;
}
void fb_init()
{
fb = open("/dev/fb0", O_RDWR);
if(fb == -1) { errno_exit("display device"); }
else { printf("*********************** Open video display success **********************\n"); }
fb_stat(fb, &fb_width, &fb_height, &fb_depth);
screensize = fb_width * fb_height * fb_depth / 8;
fbmem = fb_mmap(fb, screensize);
}
int yuv_to_rgb16(unsigned char y, unsigned char u, unsigned char v, unsigned char *rgb)
{
int r,g,b;
int z;
int rgb16;
z = 0;
r = 1.164 * (y - 16) + 1.596 * (v - 128);
g = 1.164 * (y - 16) - 0.813 * (v - 128) - 0.391 * (u -128);
b = 1.164 * (y - 16) + 2.018 * (u - 128);
if (r > 255) r = 255;
if (g > 255) g = 255;
if (b > 255) b = 255;
if (r < 0) r = 0;
if (g < 0) g = 0;
if (b < 0) b = 0;
rgb16 = (int)(((r >> 3)<<11) | ((g >> 2) << 5)| ((b >> 3) << 0));
*rgb = (unsigned char)(rgb16 & 0xFF);
rgb++;
*rgb = (unsigned char)((rgb16 & 0xFF00) >> 8);
return 0;
}
int image_convert(unsigned char *in_buf, unsigned char *rgb, int width, int height)
{
int x,y,z=0;
int blocks;
unsigned char Y1, Y2, U, V;
blocks = (width * height) * 2;
for (y = 0; y < blocks; y+=4)
{
Y1 = in_buf[y + 0];
U = in_buf[y + 1];
Y2 = in_buf[y + 2];
V = in_buf[y + 3];
yuv_to_rgb16(Y1, U, V, &rgb[y]);
yuv_to_rgb16(Y2, U, V, &rgb[y + 2]);
}
return 0;
}
int process_image_lcd(unsigned char *rgb565)
{
int x,y;
unsigned char low_byte,hig_byte;
unsigned short color;
x=y=0;
for (y=0;y<height;y++)
{
for (x=0;x<width;x++)
{
low_byte=*rgb565;
rgb565++;
hig_byte=*rgb565;
color= (unsigned short)(low_byte+hig_byte *256);
fbmem[y*width+x] =color;
rgb565++;
}
}
return 0;
}
static void process_image_fp(const void *p, int size)
{
fwrite(p, size, 1, fp);
}
static int read_frame(void)
{
unsigned int i;
struct v4l2_buffer buf;
CLEAR (buf);
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (-1 == xioctl (fd, VIDIOC_DQBUF, &buf))
{
switch (errno)
{
case EAGAIN:
return 0;
case EIO:
/* Could ignore EIO, see spec. */
/* fall through */
default:
errno_exit ("VIDIOC_DQBUF");
}
}
assert(buf.index < n_buffers);
process_image_fp(buffers[buf.index].start, buf.length);
int data_buf_len;
char *data_buffer;
int conver_result;
data_buf_len=width*height*2;
data_buffer=(unsigned char *)malloc(data_buf_len);
memset(data_buffer,0,data_buf_len);
conver_result=image_convert(buffers[buf.index].start,data_buffer,width,height);
if (conver_result<0) { errno_exit("conver_result"); }
process_image_lcd(data_buffer);
if (-1 == xioctl (fd, VIDIOC_QBUF, &buf)) errno_exit ("VIDIOC_QBUF");
return 1;
}
static void mainloop(void)
{
while(1)
{
gettimeofday(&tv0, NULL );
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;
errno_exit ("select");
}
if (0 == r)
{
fprintf (stderr, "select timeout\n");
exit (EXIT_FAILURE);
}
if (read_frame()) break;
}
gettimeofday(&tv1, NULL );
timeus = (1000000 * ( tv1.tv_sec - tv0.tv_sec ) + tv1.tv_usec - tv0.tv_usec);
tm=timeus/1000000.0;
printf(">>>>>> time = %f s\n",tm);
}
}
static void start_capturing(void)
{
unsigned int i;
enum v4l2_buf_type type;
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 == xioctl (fd, VIDIOC_QBUF, &buf)) errno_exit ("VIDIOC_QBUF");
}
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (-1 == xioctl (fd, VIDIOC_STREAMON, &type)) errno_exit ("VIDIOC_STREAMON");
}
static void init_mmap(void)
{
struct v4l2_requestbuffers req;
CLEAR(req);
req.count=4;
req.type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory=V4L2_MEMORY_MMAP;
if (-1 == xioctl (fd, VIDIOC_REQBUFS, &req))
{
if (EINVAL == errno)
{
fprintf (stderr, "%s does not support " "memory mapping\n", dev_name);
exit (EXIT_FAILURE);
}
else
{
errno_exit ("VIDIOC_REQBUFS");
}
}
if (req.count < 2)
{
fprintf (stderr, "Insufficient buffer memory on %s\n", dev_name);
exit (EXIT_FAILURE);
}
buffers = calloc(req.count, sizeof(*buffers));
if (!buffers)
{
fprintf (stderr, "Out of memory\n");
exit (EXIT_FAILURE);
}
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 == xioctl (fd, VIDIOC_QUERYBUF, &buf)) errno_exit ("VIDIOC_QUERYBUF");
buffers[n_buffers].length = buf.length;
buffers[n_buffers].start = mmap (NULL /* start anywhere */,
buf.length,
PROT_READ | PROT_WRITE /* required */,
MAP_SHARED /* recommended */,
fd, buf.m.offset);
if (MAP_FAILED == buffers[n_buffers].start) errno_exit ("mmap");
}
}
int init_capture_device()
{
struct v4l2_capability cap;
if (-1 == xioctl (fd, VIDIOC_QUERYCAP, &cap))
{
if (EINVAL == errno)
{
fprintf (stderr, "%s is no V4L2 device\n", dev_name);
exit (EXIT_FAILURE);
}
else
{
errno_exit ("VIDIOC_QUERYCAP");
}
}
if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE))
{
fprintf (stderr, "%s is no video capture device\n", dev_name);
exit (EXIT_FAILURE);
}
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);
struct v4l2_cropcap cropcap;
struct v4l2_crop crop;
CLEAR(cropcap);
cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (0 == xioctl (fd, VIDIOC_CROPCAP, &cropcap))
{
crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
crop.c = cropcap.defrect; /* reset to default */
if (-1 == xioctl (fd, VIDIOC_S_CROP, &crop))
{
switch (errno)
{
case EINVAL:
/* Cropping not supported. */
break;
default:
/* Errors ignored. */
break;
}
}
}
else
{
printf("**************** Cropcap can't use ****************\n");
}
struct v4l2_input input;
unsigned int i = 0;
while (1)
{
input.index = i;
ret = ioctl(fd, VIDIOC_ENUMINPUT, &input);
if (ret < 0) break;
printf (" inputname: %s\n", input.name);
i++;
}
CLEAR(input);
if (-1 == xioctl (fd, VIDIOC_G_INPUT, &input.index)) { errno_exit ("VIDIOC_G_INPUT");}
if (-1 == xioctl (fd,VIDIOC_ENUMINPUT, &input)) { errno_exit ("VIDIOC_ENUMINPUT");}
printf("************************ Input information ************************\n");
printf (" current inputname: %s\n", input.name);
switch (input.type) {
case V4L2_INPUT_TYPE_TUNER: printf(" V4L2_INPUT_TYPE_TUNER\n");
case V4L2_INPUT_TYPE_CAMERA: printf(" V4L2_INPUT_TYPE_CAMERA\n");
}
printf (" status: %0x\n", input.status);
struct v4l2_fmtdesc fmtdesc;
CLEAR(fmtdesc);
fmtdesc.index = 0;
fmtdesc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
printf("********************* Support Format Informations **********************\n");
while ((ret = xioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc)) == 0)
{
fmtdesc.index++;
printf(" pixelformat ''%c%c%c%c'', description ''%s''\n",
fmtdesc.pixelformat & 0xFF, (fmtdesc.pixelformat >> 8) & 0xFF, (fmtdesc.pixelformat >> 16) & 0xFF,
(fmtdesc.pixelformat >> 24) & 0xFF, fmtdesc.description);
}
unsigned int min;
struct v4l2_format fmt;
CLEAR (fmt);
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width= width;
fmt.fmt.pix.height= height;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
fmt.fmt.pix.field= V4L2_FIELD_INTERLACED;
if (-1 == xioctl (fd, VIDIOC_S_FMT, &fmt)) errno_exit ("VIDIOC_S_FMT"); /* Note VIDIOC_S_FMT may change width and height. */
/* Buggy driver paranoia. */
min = fmt.fmt.pix.width * 2;
if (fmt.fmt.pix.bytesperline < min) fmt.fmt.pix.bytesperline = min;
min = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
if (fmt.fmt.pix.sizeimage < min) fmt.fmt.pix.sizeimage = min;
if(xioctl(fd, VIDIOC_G_FMT, &fmt) == -1) { errno_exit("VIDIOC_G_FMT"); }
printf("********************* Stream Format Informations **********************\n");
printf(" current format type: %d\n", fmt.type);
printf(" current format width: %d\n", fmt.fmt.pix.width);
printf(" current format 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);
}
static void open_capture_device(void)
{
struct stat st;
if (-1 == stat (dev_name, &st)) {
fprintf (stderr, "Cannot identify '%s': %d, %s\n",
dev_name, errno, strerror (errno));
exit (EXIT_FAILURE);
}
if (!S_ISCHR (st.st_mode)) {
fprintf (stderr, "%s is no device\n", dev_name);
exit (EXIT_FAILURE);
}
fd = open (dev_name, O_RDWR /* required */ | O_NONBLOCK, 0);
if (-1 == fd) {
fprintf (stderr, "Cannot open '%s': %d, %s\n",
dev_name, errno, strerror (errno));
exit (EXIT_FAILURE);
}
}
int main(int argc, char **argv)
{
printf("*************************** Program start ***************************\n");
dev_name = "/dev/video0";
open_capture_device();
init_capture_device();
init_mmap();
start_capturing();
fb_init();
fp = fopen(filename, "wa+");
mainloop();
return 0;
}