本文是总结和整理文章：
详解解释见：http://blog.csdn.net/shaolyh/article/details/6583226
感谢原博主的分享！
src：
#include <fimc.h>
static int fd_cam=-1 ;
static struct v4l2_requestbuffers reqbuf;
static VideoBuffer framebuf[BUFFER_COUNT];
static struct v4l2_buffer buf;
int Camera_OpenCam()
{
// open device
fd_cam = open(CAMERA_DEVICE, O_RDWR, 0);
if (fd_cam < 0) {
printf("Open %s failed\n", CAMERA_DEVICE);
return -1;
}
return fd_cam ;
}
int Camera_CloseCam()
{
return close(fd_cam);
}
int Camera_GetCamInfo()
{
int ret=-1 ;
// GetDevicInfo
struct v4l2_capability cap;
ret = ioctl(fd_cam, VIDIOC_QUERYCAP, &cap);
if (ret < 0) {
printf("VIDIOC_QUERYCAP failed (%d)\n", ret);
return ret;
}
// Print capability infomations
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: %08X\n", cap.version);
printf(" capabilities: %08X\n", cap.capabilities);
return ret ;
}
int Camera_SetCamFMT()
{
int ret = -1 ;
// SetCamFMT
struct v4l2_format fmt;
memset(&fmt, 0, sizeof(fmt));
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width = VIDEO_WIDTH;
fmt.fmt.pix.height = VIDEO_HEIGHT;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
ret = ioctl(fd_cam, VIDIOC_S_FMT, &fmt);
if (ret < 0) {
printf("VIDIOC_S_FMT failed (%d)\n", ret);
return ret;
}
// GetCamFMT to Verify
ret = ioctl(fd_cam, VIDIOC_G_FMT, &fmt);
if (ret < 0) {
printf("VIDIOC_G_FMT failed (%d)\n", ret);
return ret;
}
// Print Stream Format
printf("Stream Format Informations:\n");
printf(" type: %d\n", fmt.type);
printf(" width: %d\n", fmt.fmt.pix.width);
printf(" 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);
printf(" raw_date: %s\n", fmt.fmt.raw_data);
return 0 ;
}
int Camera_RequestBuffers(struct v4l2_requestbuffers *reqbuf__)
{
// Request Buffers from kernel
int ret =-1 ;
reqbuf__->count = BUFFER_COUNT;
reqbuf__->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
reqbuf__->memory = V4L2_MEMORY_MMAP;
ret = ioctl(fd_cam , VIDIOC_REQBUFS, reqbuf__);
if(ret < 0) {
printf("VIDIOC_REQBUFS failed (%d)\n", ret);
return ret;
}
return ret ;
}
int Camera_MapAndEnqueue(struct v4l2_requestbuffers *reqbuf__, struct v4l2_buffer *buf__,VideoBuffer *framebuf_)
{
int i=-1,ret=-1 ;
// Map And Enqueue
for (i = 0; i < reqbuf__->count; i++)
{
buf__->index = i;
buf__->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf__->memory = V4L2_MEMORY_MMAP;
ret = ioctl(fd_cam , VIDIOC_QUERYBUF, buf__);
if(ret < 0) {
printf("VIDIOC_QUERYBUF (%d) failed (%d)\n", i, ret);
return ret;
}
// mmap buffer
framebuf_[i].length = buf__->length;
framebuf_[i].start = (char *) mmap(0, buf__->length, PROT_READ|PROT_WRITE, MAP_SHARED, fd_cam, buf__->m.offset);
if (framebuf_[i].start == MAP_FAILED) {
printf("mmap (%d) failed: %s\n", i, strerror(errno));
return -1;
}
// Queen buffer
ret = ioctl(fd_cam , VIDIOC_QBUF, buf__);
if (ret < 0) {
printf("VIDIOC_QBUF (%d) failed (%d)\n", i, ret);
return -1;
}
printf("Frame buffer %d: address=0x%x, length=%d\n", i, (unsigned int)framebuf_[i].start, framebuf_[i].length);
}
return 0 ;
}
void Camera_UNMap(VideoBuffer *framebuf_)
{
int i=-1 ;
// Release the resource
for (i=0; i< 4; i++)
{
munmap(framebuf_[i].start, framebuf_[i].length);
}
}
int Camera_StartCameraStreaming()
{
int ret=-1 ;
// start camera streaming
enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
ret = ioctl(fd_cam, VIDIOC_STREAMON, &type);
if (ret < 0) {
printf("VIDIOC_STREAMON failed (%d)\n", ret);
return ret;
}
return ret ;
}
int Camera_DeQueueBufferGetFrame( struct v4l2_buffer *buf_)
{
int ret=-1 ;
// De-queue buffer ,Get frame
ret = ioctl(fd_cam, VIDIOC_DQBUF, buf_);
if (ret < 0) {
printf("VIDIOC_DQBUF failed (%d)\n", ret);
return ret;
}
return ret ;
}
int Camera_EnQueueBuffer(struct v4l2_buffer *buf_)
{
int ret = -1 ;
// Re-queen buffer
ret = ioctl(fd_cam, VIDIOC_QBUF, buf_);
if (ret < 0) {
printf("VIDIOC_QBUF failed (%d)\n", ret);
return ret;
}
return 0 ;
}
void Camera_RecordYUYV(const char* YUYVFILE ,struct v4l2_buffer *buf_)
{
// record frame YUYV
FILE *fp = fopen(YUYVFILE, "wb");
if (fp < 0) {
printf("open frame data file failed\n");
return ;
}
fwrite(framebuf[buf_->index].start, 1, buf_->length, fp);
fclose(fp);
printf("Capture one frame saved in %s\n", YUYVFILE);
}
int main()
{
Camera_OpenCam();
Camera_GetCamInfo() ;
Camera_SetCamFMT();
Camera_RequestBuffers(&reqbuf);
Camera_MapAndEnqueue(&reqbuf,&buf,framebuf);
Camera_StartCameraStreaming();
Camera_DeQueueBufferGetFrame(&buf);
Camera_RecordYUYV(CAPTURE_FILE,&buf);
Camera_EnQueueBuffer(&buf);
Camera_UNMap(framebuf);
Camera_CloseCam();
printf("Camera test Done.\n");
return 0;
}
header：
#ifndef FIMC_H_
#define FIMC_H_
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <getopt.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <malloc.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <asm/types.h>
#include <linux/videodev2.h>
#define CAMERA_DEVICE "/dev/video0"
#define CAPTURE_FILE "frame-yuyv.yuv"
#define VIDEO_WIDTH 640
#define VIDEO_HEIGHT 480
#define VIDEO_FORMAT V4L2_PIX_FMT_YUYV
#define BUFFER_COUNT 4
typedef struct VideoBuffer {
void *start;
size_t length;
} VideoBuffer;
#endif /* FIMC_H_ */
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作者：放牛娃不吃草
来源：CSDN
原文：https://blog.csdn.net/gubenpeiyuan/article/details/37726887
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