image capture with ov9655 camera and intel pxa270C5C520

* image capture with ov9655 camera and intel pxa270C5C520
@ 2009-11-23 18:39 Kai Tiwisina
  2009-11-23 20:40 ` Guennadi Liakhovetski
  0 siblings, 1 reply; 5+ messages in thread
From: Kai Tiwisina @ 2009-11-23 18:39 UTC (permalink / raw)
  To: linux-media

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Hello,

my name is Kai Tiwisina and i'm a student in germany and i'm trying to 
communicate with a Omnivision ov9655 camera which is atteched with my 
embedded linux system via the v4l commands.

I've written a small testprogram which should grow step by step while i'm 
trying one ioctl after another.
Everything worked fine until i tried to use the VIDIOC_S_FMT ioctl. It's 
always giving me an "invalid argument" failure and i don't know why.

Perhaps someone of you is able to help me with this ioctl and give an 
advice for a simple flow chart for a single frame image capture. Which 
ioctl steps are neccessary and where do i need loops and for what, because 
the capture-example.c from bytesex.org is way too general for my purpose.

Thanks in advance

Kai Tiwisina    

-- 
Jetzt kostenlos herunterladen: Internet Explorer 8 und Mozilla Firefox 3.5 -
sicherer, schneller und einfacher! http://portal.gmx.net/de/go/atbrowser

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/*
 ============================================================================
 Name        : stream_test.c
 Author      : Kai Tiwisina
 Version     :
 Description : Output of camera stream in to text-file
 ============================================================================
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>              // open() is in here
#include <unistd.h>				// close() is in here
#include <errno.h>				// used for desolving error numbers
#include <sys/ioctl.h>			// ioctl() is in here
#include <sys/mman.h>
#include <linux/videodev.h>		// jpeg_markers are defined in here
#include <asm/types.h>			// for videodev2.h
#include <linux/videodev2.h>	// VIDIOC_QUERYCAP & struct v4ls_capability are defined in here

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

void print_errno(char *s);	//returns errno argument as value and expression
void open_device();	//opens a v4l device returning new file descriptor and gives error info if necessary
void query_cap();
void request_buffer();
void stream_on();
void query_buffer();
void memory_mapping();
void stream_off();
void get_format();
void set_format();

static struct v4l2_requestbuffers buffer;
static struct v4l2_buffer q_buffer;
static struct v4l2_format f_type;

static int fd;								// fd is the file descriptor

int main(void)
{
	open_device();
	printf("\n\n*New file descriptor: %i*\n\n",fd);
	query_cap();
	request_buffer();
	get_format();
	set_format();
	get_format();
	//stream_on();
	//query_buffer();
	//memory_mapping();
	//stream_off();
	close(fd);						//closes connection to device
	return 0;
}

void print_errno(char *s)
{
	printf("Process %s failed %d, %s\n", s, errno, strerror(errno));
	exit(EXIT_FAILURE);
}

void open_device()
{
	int status;
	status=open("/dev/video0",O_RDWR);	//Look up arguments for v4l2 open() in v4l_doku.pdf
	if(status==-1)						//Device_name has to include the whole path, here /dev
	{
		print_errno("open_device");
	}
	else
	{
		fd=status;
	}
}

void query_cap()
{
	int status;
	struct v4l2_capability camera_cap; // camera_cap should be representative for the bebot's cam
	status=ioctl(fd,VIDIOC_QUERYCAP,&camera_cap); // description on Page 188 in v4l_doku.pdf
	if(status==-1)
	{
		print_errno("Determination of device capabilities");
	}
	else
	{
		printf("driver:\t%s\n",camera_cap.driver);
		printf("card:\t%s\n",camera_cap.card);
		printf("bus_info:\t%s\n",camera_cap.bus_info);
		printf("version:\t%u.%u.%u\n",(camera_cap.version >> 16)&0xFF,(camera_cap.version >> 8)&0xFF,camera_cap.version&0xFF);
		printf("capabilities:\t%x(HEX)\n",camera_cap.capabilities);
	}
}

void request_buffer()
{
	int status;
	memset(&buffer,0,sizeof(buffer));
	buffer.type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
	buffer.memory=V4L2_MEMORY_MMAP;
	buffer.count=2;
	status=ioctl(fd,VIDIOC_REQBUFS,&buffer);
	if(status==-1)
	{
		print_errno("request buffer");
	}
	else
	{
		printf("buffer allocated %i times %i\n",sizeof(buffer),sizeof(unsigned char));
	}

}

void stream_on()
{
	int status;
	status=ioctl(fd,VIDIOC_STREAMON,&buffer.type);
	if(status==-1)
	{
		print_errno("activating streaming device");
	}
	else
	{
		printf("streaming device activated\n");
	}
}

void query_buffer()
{
	int status;
	q_buffer.type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
	q_buffer.index=1;
	status=ioctl(fd,VIDIOC_QUERYBUF,&q_buffer);
	if(status==-1)
	{
		print_errno("querying buffer informations");
	}
	else
	{
		printf("index:\t%u\n",q_buffer.index);
		printf("buffer_type:\t%u\n",q_buffer.type);
		printf("bytes used:\t%u\n",q_buffer.bytesused);
		printf("flags:\t%u\n",q_buffer.flags);
		printf("field:\t%u\n",q_buffer.field);
		//printf("time_stamp:\t%i\n",q_buffer.timestamp);
		//printf("time_code:\t%i\n",q_buffer.timecode);
		printf("sequence:\t%u\n",q_buffer.sequence);
		printf("memory:\t%u\n",q_buffer.memory);
		printf("offset:\t%u\n",q_buffer.m.offset);
		printf("user_pointer:\t%lu\n",q_buffer.m.userptr);
		printf("length:\t%u\n",q_buffer.length);
		printf("input:\t%u\n",q_buffer.input);
		printf("\n\nstreaming device activated\n");
	}
}

void memory_mapping()
{
	int i,j,status;
	char *mem,*temp;
	FILE* fp;
	mem=mmap(NULL,q_buffer.length,PROT_READ|PROT_WRITE,MAP_SHARED,fd,q_buffer.m.offset);
	if(mem==MAP_FAILED)
	{
		print_errno("memory mapping");
	}
	else
	{
		temp=mem;
		get_format(fd);
		fp=fopen("/home/root/image.txt","r+");
		for(i=0;i<f_type.fmt.pix.height;i++)
		{
			for(j=0;j<f_type.fmt.pix.width;j++)
			{
				fprintf(fp,"%c\t",*temp);
				temp++;
			}
			fprintf(fp,"\n");
		}
		status=munmap(mem,q_buffer.length);
		if(status==-1)
		{
			print_errno("memory unmapping");
		}
	}
}

void stream_off()
{
	int status;
	status=ioctl(fd,VIDIOC_STREAMOFF,&buffer.type);
	if(status==-1)
	{
		print_errno("deactivating streaming device");
	}
	else
	{
		printf("streaming device deactivated\n");
	}
}

void get_format()
{
	int status;
	//struct v4l2_format f_type;
	f_type.type=1;
	status=ioctl(fd,VIDIOC_G_FMT,&f_type);
	if(status==-1)
	{
		print_errno("get_format");
	}
	else
	{
		printf("\n\nbuffer type:\t%i\n",f_type.type);
		printf("image size:\t%ix%i pixels \n",f_type.fmt.pix.width,f_type.fmt.pix.height);
		printf("pixelformat:\t%i\n",f_type.fmt.pix.pixelformat);
		printf("v4l2 field-type:\t%i\n",f_type.fmt.pix.field);
		printf("bytes per line:\t%i\n",f_type.fmt.pix.bytesperline);
		printf("image size:\t%i\n",f_type.fmt.pix.sizeimage);
		printf("v4l2_colorspace-type:\t%i\n",f_type.fmt.pix.colorspace);
	}
}

void set_format()
{
	int status;
	CLEAR(f_type);
	f_type.type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
	//f_type.fmt.pix.colorspace=V4L2_COLORSPACE_SRGB;
	f_type.fmt.pix.pixelformat=V4L2_PIX_FMT_RGB555;
	f_type.fmt.pix.field=V4L2_FIELD_NONE;
	f_type.fmt.pix.height=640;
	f_type.fmt.pix.width=480;
	//f_type.fmt.pix.bytesperline=f_type.fmt.pix.width*3;
	//f_type.fmt.pix.sizeimage=f_type.fmt.pix.bytesperline*f_type.fmt.pix.height;

	status=ioctl(fd,VIDIOC_S_FMT,&f_type);
	if(status==-1)
	{
		print_errno("set_format");
	}
	else
	{
		printf("\n\nbuffer type:\t%i\n",f_type.type);
		printf("image size:\t%ix%i pixels \n",f_type.fmt.pix.width,f_type.fmt.pix.height);
		printf("pixelformat:\t%i\n",f_type.fmt.pix.pixelformat);
		printf("v4l2 field-type:\t%i\n",f_type.fmt.pix.field);
		printf("bytes per line:\t%i\n",f_type.fmt.pix.bytesperline);
		printf("image size:\t%i\n",f_type.fmt.pix.sizeimage);
		printf("v4l2_colorspace-type:\t%i\n",f_type.fmt.pix.colorspace);
	}
}

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