/*
?*??V4L2?video?capture?example
?*
?*??This?program?can?be?used?and?distributed?without?restrictions.
?*/

#include?
#include?
#include?
#include?


#include??????????????/*?getopt_long（）?*/

#include???????????????/*?low-level?i/o?*/
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?

#include???????????/*?for?videodev2.h?*/

#include?

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

typedef?enum?{
????????IO_METHOD_READ
????????IO_METHOD_MMAP
????????IO_METHOD_USERPTR
}?io_method;

struct?buffer?{
????????void?*??????????????????start;
????????size_t??????????????????length;
};

static?char?*???????????dev_name????????=?NULL;
static?io_method????????io??????????????=?IO_METHOD_MMAP;
static?int??????????????fd??????????????=?-1;
struct?buffer?*?????????buffers?????????=?NULL;
static?unsigned?int?????n_buffers???????=?0;

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?fdint?requestvoid?*?arg）
{
????????int?r;

????????do?r?=?ioctl?（fd?request?arg）;
????????while?（-1?==?r?&&?EINTR?==?errno）;

????????return?r;
}

static?void?process_image（const?void?*?p）
{
????????fputc?（‘.‘?stdout）;
????????fflush?（stdout）;
}

//從內(nèi)核緩沖區(qū)取出一幀數(shù)據(jù)
static?int?read_frame（void）
{
//2015.12.12_18:33:zhou_add	
//		static?int?i?=?0;
//end

????????struct?v4l2_buffer?buf;
????????unsigned?int?i;

????????switch?（io）?
		{
	????????case?IO_METHOD_READ:
	????????????????if?（-1?==?read?（fd?buffers[0].start?buffers[0].length））?
					{
	????????????????????????switch?（errno）?
							{
		????????????????????????case?EAGAIN:
		????????????????????????????????return?0;

		????????????????????????case?EIO:
		????????????????????????????????/*?Could?ignore?EIO?see?spec.?*/

		????????????????????????????????/*?fall?through?*/

		????????????????????????default:
		????????????????????????????????errno_exit?（“read“）;
	????????????????????????}
	????????????????}

	????????????????process_image?（buffers[0].start）;

					
	????????????????break;

	????????case?IO_METHOD_MMAP:
	????????????????CLEAR?（buf）;

	????????????????buf.type?=?V4L2_BUF_TYPE_VIDEO_CAPTURE;
	????????????????buf.memory?=?V4L2_MEMORY_MMAP;
					/*從內(nèi)核環(huán)形緩沖區(qū)取出一幀數(shù)據(jù)*/
	????????????????if?（-1?==?xioctl?（fd?VIDIOC_DQBUF?&buf））?{
	????????????????????????switch?（errno）?{
		????????????????????????case?EAGAIN:
		????????????????????????????????return?0;

		????????????????????????case?EIO:
		????????????????????????????????/*?Could?ignore?EIO?see?spec.?*/

		????????????????????????????????/*?fall?through?*/

		????????????????????????default:
		????

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件???????20525??2015-12-13?20:08??v4l2.c
?????文件???????61593??2015-12-12?16:19??v4l2.h