read a v4l2 vpu decoder device's name, capability, in/out format

v4l2_read_info.c

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/videodev2.h>
#include <sys/ioctl.h>

int main(int argc, char *argv[]) {

	int fd;
	struct v4l2_capability cap; 
	struct v4l2_fmtdesc fmtdesc; 

	fd = open("/dev/video9", O_RDWR);
	if (fd == -1)
	{
		perror("Opening Video device");
		return 1;
	}

	ioctl(fd,VIDIOC_QUERYCAP,&cap); 
	printf("Driver Name:%s\nCard Name:%s\nBus info:%s\ncaps:0x%x\n",\
		cap.driver,\
		cap.card,\
		cap.bus_info,\
		cap.device_caps); 

	fmtdesc.index=0; 
	fmtdesc.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; 

	printf("input format:\n"); 
	while(ioctl(fd,VIDIOC_ENUM_FMT,&fmtdesc)!=-1) 
	{ 
		printf("/t%d.%s\n",fmtdesc.index+1,fmtdesc.description); 
		fmtdesc.index++; 
	} 

	fmtdesc.index=0; 
	fmtdesc.type=V4L2_BUF_TYPE_VIDEO_OUTPUT; 

	printf("out format:\n"); 
	while(ioctl(fd,VIDIOC_ENUM_FMT,&fmtdesc)!=-1) 
	{ 
		printf("/t%d.%s\n",fmtdesc.index+1,fmtdesc.description); 
		fmtdesc.index++; 
	} 
	
	close(fd);
	return 0;
}