Hi Yurij,
I tried your sample program. The output is as follows.
Memory map buffer:
size: 17039360
frames: 8
Memory mapped to 0xffffffff
Error: Grabber chip can't sync
How to rectify the error? In my case the tv norm is PAL. I have some
doubts in source code.
map = mmap(0, mywidth * myheight * 2 + 4096,
PROT_READ|PROT_WRITE,MAP_SHARED, fd, 0);
Why the "4096" in mmap ?
char *ppm_hdr = "P6\n# CREATOR: anonimous :-) (RGB565)\n640
480\n255\n";
what is this "ppm_hdr" and why it is initialised as above ?
The output of "v4linfo" is as follows for your perception.
### video4linux device info [/dev/video0] ###
general info
VIDIOCGCAP
name : "BT878(Prolink PixelView PlayT)"
type : 0xab [CAPTURE,TUNER,OVERLAY,CLIPPING,SCALES]
channels : 3
audios : 1
maxwidth : 924
maxheight : 576
minwidth : 48
minheight : 32
VIDIOC_QUERYCAP
driver : "bttv"
card : "BT878(Prolink PixelView PlayT)"
bus_info : "PCI:01:05.0"
version : 0.9.11
capabilities : 0x5010015
[VIDEO_CAPTURE,VIDEO_OVERLAY,VBI_CAPTURE,TUNER,READWRITE,STREAMING]
picture
VIDIOCGPICT
brightness : 50400
hue : 31456
colour : 30801
contrast : 26214
whiteness : 0
depth : 24
palette : RGB24
buffer
VIDIOCGFBUF
base : 0xe8000000
height : 600
width : 800
depth : 32
bytesperline : 4096
window
VIDIOCGWIN
x : 0
y : 0
width : 320
height : 240
chromakey : 0
flags : 0
channels
VIDIOCGCHAN(0)
channel : 0
name : "Television"
tuners : 1
flags : 0x3 [TUNER,AUDIO]
type : TV
norm : 0
VIDIOCGCHAN(1)
channel : 1
name : "Composite1"
tuners : 0
flags : 0x2 [AUDIO]
type : CAMERA
norm : 0
VIDIOCGCHAN(2)
channel : 2
name : "S-Video"
tuners : 0
flags : 0x2 [AUDIO]
type : CAMERA
norm : 0
tuner
VIDIOCGTUNER
tuner : 0
name : "Television"
rangelow : 0
rangehigh : 2147483647
flags : 0x7 [PAL,NTSC,SECAM]
mode : PAL
signal : 65535
audio
VIDIOCGAUDIO
audio : 0
volume : 0
bass : 0
treble : 0
Thanks in advance.
With Regards,
S.Suriya Mohan.
On Wed, 01 Oct 2003 Yurij Sysoev wrote :
>Hi,
>
>there is a really brain-dead one :-)
>
>8<------------------------ begin
---------------------------------------------------
>/*
> v4l single frame grabber sample
>*/
>
>#include <stdlib.h>
>#include <stdio.h>
>#include <fcntl.h>
>#include <sys/ioctl.h>
>#include <sys/mman.h>
>#include <sys/stat.h>
>#include <errno.h>
>
>#include <linux/videodev.h>
>
>const int mywidth = 640; // !!!!!!!
>const int myheight = 480; // NTSC-J - pls, put your here
>
>static struct video_capability capability;
>
>static int fd = -1;
>
>static int ret_bytes,vfd;
>
>static char *map = NULL;
>static char *dest_buf=NULL;
>static char src_buf[691200];
>
>
>static struct video_mbuf gb_buffers;
>static struct video_mmap my_buf;
>
>int main(void)
>{
> int mymode;
> int no_bytes,i;
> char my_video_dev[100] = "/dev/video0";
> // Open video device
>
> if (-1 == (fd = open(my_video_dev, O_RDWR)))
> {
> printf("Error opening device: %s\n", my_video_dev);
> goto err;
> }
> // Get video device captions
>
> if (-1 == ioctl(fd,VIDIOCGCAP,&capability))
> {
> printf("Error: ioctl(fd,VIDIOCGCAP,&capability)\n");
> goto err;
> }
> fcntl(fd,F_SETFD,FD_CLOEXEC);
> // Get number and size of the internal buffers
>
> if (-1 == ioctl(fd, VIDIOCGMBUF, &gb_buffers))
> {
> printf("Error: Error getting buffers, I think\n");
> goto err;
> }
>
> printf("Memory map buffer:\nsize: %d\nframes: %d\n\n",
> gb_buffers.size,
> gb_buffers.frames);
> // Mapping internal driver's buffers to the user space
>
> map = mmap(0, mywidth * myheight * 2 + 4096,
PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
> if (map == NULL)
> {
> printf("Error: mmap returned NULL\n");
> goto err;
> }
> printf("Memory mapped to 0x%08x\n", map);
> // set capture dimensions and format
>
> my_buf.width = mywidth;
> my_buf.height = myheight;
> my_buf.format = VIDEO_PALETTE_RGB565;
>
> my_buf.frame = 0;
> // start capture
>
> if (-1 == ioctl(fd, VIDIOCMCAPTURE, &my_buf))
> {
> printf("Error: Grabber chip can't sync\n");
> goto err;
> }
> // wait for end of the frame capturing
> if (-1 == ioctl(fd, VIDIOCSYNC, &my_buf.frame))
> {
> printf("Error on sync!\n");
> goto err;
> }
> memcpy(src_buf, map, mywidth * myheight * 2);
>
> {
> int i, j, k;
> char r, g, b;
> unsigned short *ptr = (unsigned short *)src_buf;
> unsigned short word;
> char *ppm_hdr = "P6\n# CREATOR: anonimous :-) (RGB565)\n640
480\n255\n";
> int vfd = open("video-data.ppm",O_RDWR | O_CREAT, S_IRUSR |
S_IWUSR);
> k = 0;
> write(vfd, ppm_hdr, strlen(ppm_hdr));
> for(i = 0; i < myheight; i++)
> for(j = 0; j < mywidth; j++)
> {
> word = ptr[k];
> r = (word >> 8) & 0xf8;
> g = (word >> 3) & 0xfc;
> b = (word << 3) & 0xf8;
> write(vfd, &r, 1);
> write(vfd, &g, 1);
> write(vfd, &b, 1);
> k++;
> }
> close(vfd);
> }
>
> munmap(map, mywidth * myheight * 2 + 4096);
>
> printf("Press enter to quit\n");
> getchar();
> return 0;
>
>err:
> return -1;
>}
>
>8<---------------------------- end
------------------------------------------------------------------------------------
>
>Mauricio Henriquez wrote:
>
>>Hi:
>> My name is Mauricio and I write you from Chili.
>> I have a Phoebe TV-Master+FM working fine with my redhat 8
system, I like to do some basic test and I need some basic "C" or
"C++" example code about how to set and capture a image from the
capture card and saved in some image format in my hard drive. If any
of you have some basic sample code I very appriciate.
>> For advance thanks.
>> Mauricio Henriquez
>>
>
>
>
>
>--
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