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/*
*File Name:v4l.c
*author:gufeiyang 2.10-3.20
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <error.h>
#include <errno.h>/*errno undeclared*/
#include <linux/videodev.h>
#include <sys/mman.h>
#include <assert.h>
#include <string.h>
#include <assert.h>
#include <jpeglib.h> /*jpeg*/
#include "v4l.h"
/*Get Information*/
/*用ioctl方法取得设备文件的相关信息，存入struct capability结构体*/
int v4l_get_capability(v4l_device *vd)
{
if(ioctl(vd->fd, VIDIOCGCAP, &(vd->capability)) < 0) {
perror("v4l_get_capability:");
return -1;
}
return 0;
}
/*取得视频采集的通道数目*/
int v4l_get_channels(v4l_device *vd)
{
int i;
for(i = 0; i < vd->capability.channels; i++ ) {
vd->channel[i].channel = i;
if(ioctl(vd->fd, VIDIOCGCHAN, &(vd->channel[i])) < 0){
perror("v4l_get_channels:");
return -1;
}
}
return 0;
}
/*切换视频采集通道*/
int v4l_switch_channel(v4l_device *vd, int c)
{
if(ioctl(vd->fd, VIDIOCSCHAN, &(vd->channel[c])) < 0){
perror("v4l_switch_channel:");
return -1;
}
return 0;
}
/*获得audios的信息*/
int v4l_get_audios(v4l_device *vd)
{
int i;
for(i = 0; i < vd->capability.audios; i++){
vd->audio[i].audio = i;
if(ioctl(vd->fd,VIDIOCGAUDIO, &(vd->audio[i])) < 0){
perror("v4l_get_audios:");
return -1;
}
}
return 0;
}
/*information end*/
/*Set */
/*获得输入到视频采集卡的影像信息*/
int v4l_get_picture(v4l_device *vd)
{
if(ioctl(vd->fd, VIDIOCGPICT, &(vd->picture)) < 0) {
perror("v4l_get_picture:");
return -1;
}
return 0;
}
/*设置设备的属性*/ //先为分量赋新值，再调用VIDIOCSPICT
int v4l_set_picture(v4l_device *vd){
if(ioctl(vd->fd,VIDIOCSPICT,&(vd->picture))<0)
return -1;
else
return 0;
}
/*对所有的通道设置norm，完成需v4l_get_capability和v4l_get_picture，确保每个通道都设置成功*/
int v4l_set_norm(v4l_device *vd, int norm)
{
int i;
for (i = 0; i < vd->capability.channels; i++) {
vd->channel[i].norm = norm;
}
if (v4l_get_capability(vd)) {
perror("v4l_set_norm");
return -1;
}
if (v4l_get_picture(vd)) {
perror("v4l_set_norm");
}
return 0;
}
/*打开视频设备*/
int v4l_open(char *dev, v4l_device *vd)
{
if(!dev)
dev = DEFAULT_DEVICE;
if((vd->fd = open(dev, O_RDWR)) < 0) {
perror("v4l_open:");
return -1;
}
return 0;
}
/*关闭*/
int v4l_close(v4l_device *vd)
{
munmap(vd->map,vd->mbuf.size);
close(vd->fd);
return 0;
}
int v4l_get_mbuf(v4l_device *vd)
{
if(ioctl(vd->fd,VIDIOCGMBUF, &(vd->mbuf)) < 0){
perror("v4l_get_mbuf:");
return -1;
}
return 0;
}
/*初始化mmap,用途是将文件map到内存
*mmap(0, vd->mbuf.size, PROT_READ|PROT_WRITE, MAP_SHARED, vd->fd, 0)
*0:起始位置
*vd->mbuf.size：长度
*PROT_READ|PROT_WRITE：可读写
*MAP_SHARED:可以与其他进程共享
*vd->fd：file description
*0:offset
*/
int v4l_mmap_init(v4l_device *vd)
{
if(v4l_get_mbuf(vd) < 0)
return -1;
if((vd->map = mmap(0, vd->mbuf.size, PROT_READ|PROT_WRITE, MAP_SHARED, vd->fd, 0)) < 0){
perror("v4l_mmap_init:mmap");
return -1;
}
return 0;
}
int v4l_grab_frame(v4l_device *vd, int frame)
{
if (vd->frame_using[frame]) {
fprintf(stderr, "get_grab_frame: frame %d is already used.\n", frame);
return -1;
}
vd->mmap.frame = frame;
if (ioctl(vd->fd, VIDIOCMCAPTURE, &(vd->mmap)) < 0) {
perror("v4l_grab_frame");
return -1;
}
vd->frame_using[frame] = 1;
vd->frame_current = frame;
return 0;
}
/*根据图像信息初始化mmap里面的设置*/
int v4l_grab_init(v4l_device *vd, int width, int height)
{
vd->mmap.width = width;
vd->mmap.height = height;
vd->mmap.format = VIDEO_PALETTE_JPEG;
vd->frame_current = 0;
vd->frame_using[0] = FALSE;
vd->frame_using[1] = FALSE;
return v4l_grab_frame(vd, 0);
}
/*同步，等待图像采集完成*/
int v4l_grab_sync(v4l_device *vd)
{
if(ioctl(vd->fd, VIDIOCSYNC, &(vd->frame_current)) < 0){
perror("v4l_grab_sync");
}
vd->frame_using[vd->frame_current] = FALSE;
return 0;
}
/*获取缓冲空间*/
int v4l_get_buffer(v4l_device *vd)
{
if(ioctl(vd->fd,VIDIOCGFBUF, &(vd->buffer)) < 0){
perror("v4l_get_buffer:");
}
return 0;
}
int v4l_set_buffer(v4l_device *vd)
{
if(ioctl(vd->fd,VIDIOCSFBUF,&(vd->buffer)) < 0){
perror("v4l_set_buffer:");
return -1;
}
return 0;
}
/*开始采集*/
int device_grab_frame(v4l_device *vd)
{
vd->frame_current = 0;
if (v4l_grab_frame(vd, 0) < 0)
return -1;
return 0;
}
/*采集下一帧图像*/
int device_next_frame(v4l_device *vd)
{
vd->frame_current ^= 1;
if (v4l_grab_frame(vd, vd->frame_current) < 0)
return -1;
return 0;
}
/*获取mmap的地址*/
char * v4l_get_mapaddress( v4l_device *vd,int frame)
{
char *frameaddress=NULL;
frameaddress=vd->map+vd->mbuf.offsets[frame];
if(frameaddress>0){
return frameaddress;
}
else
return NULL;
}
/*
* *img: the address of the data that cam collected
* with height : image with height
*quality: 0-100
*/
int write_jpeg(char *filename,unsigned char *buf,int quality,int width, int height, int gray)
{
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
FILE *fp;
int i=0;
unsigned char *line;
int line_length;
if ((fp = fopen(filename,"w")) == NULL ){
fprintf(stderr,"grab: can't open %s: %s\n",filename,strerror(errno));
return -1;
}
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_compress(&cinfo);
jpeg_stdio_dest(&cinfo, fp);
cinfo.image_width = width;
cinfo.image_height = height;
cinfo.input_components = gray ? 1: 3;
cinfo.in_color_space = gray ? JCS_GRAYSCALE: JCS_RGB;
jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, quality, TRUE);
jpeg_start_compress(&cinfo, TRUE);
line_length = gray ? width : width * 3;
for (i = 0, line = buf; i < height; i++, line += line_length)
jpeg_write_scanlines(&cinfo, &line, 1);
jpeg_finish_compress(&(cinfo));
jpeg_destroy_compress(&(cinfo));
fclose(fp);
return 0;
}
//同步
int v4l_sync(v4l_device *vd){
if(ioctl(vd->fd, VIDIOCSYNC, &(vd->frame_current))<0){
exit(-1);
return -1;
}
vd->frame_using[vd->frame_current] = FALSE;
return 0;
}
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