USB摄像头通过v4l2技术采集、储存视频

Linux下通过v4l2技术采集USB摄像头的视频，然后通过x264编码器编码成视频储存起来

#include “cam.h“
#include “x264_encode.h“

#include “net.h“

int usTimer（long us）
{
    struct timeval timeout;
    timeout.tv_sec = 0;
    timeout.tv_usec = us;

    return select（0NULLNULLNULL&timeout）;
}

int yuyv_to_yuv420p（const unsigned char *in unsigned char *out unsigned int width unsigned int height）
{
    
    unsigned char *y = out;
    unsigned char *u = out + width*height;
    unsigned char *v = out + width*height + width*height/4;

    unsigned int ij;
    unsigned int base_h;
    unsigned int is_y = 1 is_u = 1;
    unsigned int y_index = 0 u_index = 0 v_index = 0;

    unsigned long yuv422_length = 2 * width * height;

    //序列为YU YV YU YV，一个yuv422帧的长度 width * height * 2 个字节
    //丢弃偶数行 u v

    for（i=0; i    {
        *（y+y_index） = *（in+i）;
        y_index++;
    }

    for（i=0; i    {
        base_h = i*width*2;
        for（j=base_h+1; jse_h+width*2; j+=2）
        {
            if（is_u）{
                *（u+u_index） = *（in+j）;
                u_index++;
                is_u = 0;
            }
            else{
                *（v+v_index） = *（in+j）;
                v_index++;
                is_u = 1;
            }
        }
    }

    return 1;
}


int open_cam（）
{
    struct v4l2_capability cap;
    cam_fd = open（DEV_NAME O_RDWR | O_NONBLOCK 0）;  //非阻塞方式打开摄像头
    if （cam_fd < 0）
    {
        perror（“open device failed!“）;
        return -1;
    }

    /*获取摄像头信息*/
    if （ioctl（cam_fd VIDIOC_QUERYCAP &cap） < 0）
    {
        perror（“get info failed!“）;
        return -1;
    }

    printf（“Driver Name:%s\n Card Name:%s\n Bus info:%s\n version:%d\n capabilities:%x\n \n “ cap.driver cap.card cap.bus_infocap.versioncap.capabilities）;
             
    if （（cap.capabilities & V4L2_CAP_VIDEO_CAPTURE） == V4L2_CAP_VIDEO_CAPTURE）
    {
        printf（“Device %s: supports capture.\n“DEV_NAME）;
    }
    if （（cap.capabilities & V4L2_CAP_STREAMING） == V4L2_CAP_STREAMING）
    {
        printf（“Device %s: supports streaming.\n“DEV_NAME）;
    }
    return 0;
}

int set_cap_frame（）
{
    struct v4l2_format fmt;
    /*设置摄像头捕捉帧格式及分辨率*/
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    fmt.fmt.pix.width = WIDTH;   
    fmt.fmt.pix.height = HEIGHT;
    fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;   //图像存储格式设为YUYV（YUV422）

    if （ioctl（cam_fd VIDIOC_S_FMT &fmt） < 0）
    {
        perror（“set fmt failed!“）;
        return -1;
    }

    printf（“fmt.type:%d\n“fmt.type）;
    printf（“pix.pixelformat:%c%c%c%c\n“ \
            fmt.fmt.pix.pixelformat & 0xFF\
            （fmt.fmt.pix.pixelformat >> 8） & 0xFF \
            （fmt.fmt.pix.pixelformat >> 16） & 0xFF\
            （fmt.fmt.pix.pixelformat >> 24） & 0xFF）;
    printf（“pix.width:%d\n“fmt.fmt.pix.width）;
    printf（“pix.height:%d\n“fmt.fmt.pix.height）;
    printf（“pix.fiel

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2019-03-26 14:04  v4l2_h264\
     目录           0  2019-03-26 14:04  v4l2_h264\UVC_record_ubuntu\
     目录           0  2019-03-26 14:04  v4l2_h264\UVC_record_ubuntu\UVC_record\
     目录           0  2019-03-26 14:04  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\
     文件         297  2016-07-27 14:20  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\Makefile
     文件       34536  2016-07-27 11:17  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\avilib.c
     文件        6258  2016-07-27 11:17  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\avilib.h
     文件       50552  2016-07-27 14:24  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\avilib.o
     文件       69072  2016-07-27 14:24  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\camera_MJPEG
     文件        2349  2016-07-27 14:13  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\main.c
     文件       19848  2016-07-27 14:24  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\main.o
     文件        8844  2016-07-27 12:06  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\video_capture.c
     文件        1357  2016-07-27 11:18  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\video_capture.h
     文件       30080  2016-07-27 14:24  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_1\video_capture.o
     目录           0  2019-03-26 14:04  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\
     文件         350  2016-07-27 18:00  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\Makefile
     文件       34536  2016-07-27 11:17  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\avilib.c
     文件        6258  2016-07-27 11:17  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\avilib.h
     文件        4012  2015-11-17 15:01  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\color.c
     文件        2902  2015-11-17 15:01  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\color.h
     文件         308  2016-07-27 14:59  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\for_MJPEG
     文件        3644  2016-07-27 17:24  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\h264encoder.c
     文件         573  2016-07-26 15:31  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\h264encoder.h
     文件        5652  2015-11-17 15:01  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\huffman.h
     目录           0  2019-03-26 14:04  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\include\
     文件       40894  2016-07-26 15:20  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\include\x264.h
     文件         245  2012-04-17 13:43  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\include\x264_config.h
     目录           0  2019-03-26 14:04  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\lib\
     文件     1026684  2012-04-29 15:42  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\lib\libx264.a
     文件        1495  2016-07-27 18:24  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\main.c
     文件       28788  2016-07-18 18:22  v4l2_h264\UVC_record_ubuntu\UVC_record\uvc_avilib_2\utils.c
............此处省略97个文件信息