1.win+r打开运行。
2.在运行中键入services.msc回车，打开服务。
3.右边下拉找到VMware Authorization Service。
4.双击打开属性，启动类型->自动，点击驱动，点击应用，点击确定。这个时候已经授权虚拟机能访问到摄像头了。
5.打开虚拟机，点击"虚拟机"->可移动设备，找到摄像头camera，点击链接。此时虚拟机完成对摄像头的接管。
6.查看在/dev/下有video的文件。
安装cheese，打开摄像头：
sudo apt-get install cheese在终端输入cheese回车->此时可以看到打开的摄像头。
查看设备类型
ffmpeg -devices可以看到有video4linux2,v4l2这个选项
“ v4l2”可以用作“ video4linux2”的别名。
alsa是音频类型，见另一篇：虚拟机使用pc麦克风声卡
根据设备类型查看具体设备名
ffmpeg -sources video4linux2或
ffmpeg -sources v4l2可以看到有这两个设备，这两个设备对应pc的摄像头
/dev/video1 [Integrated Camera: Integrated I]
/dev/video0 [Integrated Camera: Integrated C]用命令打开摄像头，另一个不能用来打开
ffplay -f video4linux2 -video_size 640x480 -pixel_format yuyv422 -framerate 30 -i /dev/video0查看设备输入输出参数
ffmpeg -h demuxer=v4l2如查看都支持哪些像素格式
ffplay -f video4linux2 -list_formats all /dev/video0这些选项也可以用代码设置，"video_size"等名称与ffmpeg -h demuxer=v4l2 命令列举的名称一样。
AVDictionary *options = NULL;
av_dict_set(&options, “video_size”, “1920x1080”, 0);
av_dict_set(&options, “framerate”, “30”, 0);
//以上参数如果不设置的话，ffmpeg就会用默认值，但默认值摄像头不一定支持
int re = avformat_open_input(&ic, “/dev/video0”, ifmt, &options);
其次对于显示在/dev/video中的摄像头其实都是支持UVC协议的摄像头，一般说摄像头免驱动也是基于UVC开发的，我们可以用luvcview这款软件查看所有基于UVC的摄像头的信息，对于ubuntu12，可以直接执行下列命令安装，因为当时是为ubuntu12设计的：
sudo apt-get install luvcview
对于其他版本，可以到官网下载deb包安装，连接：
luvcview_0.2.6-5_amd64.deb (52.3 KiB) 安装好后
打开摄像头
luvcview -l打开摄像头
luvcview -d /dev/video1 -f yuv -s 640x480查看设备支持的像素格式和帧率
luvcview -d /dev/video0 -L可以看到支持的像素格式：MJPG YUYV RGB3 BGR3 YU12 YV12
Time interval between frame: 1/30 也就是帧间的时间间隔，也就是帧率了。
luvcview 0.2.6
SDL information:
Video driver: x11
A window manager is available
Device information:
Device path: /dev/video0
{ pixelformat = 'MJPG', description = 'Motion-JPEG' }
{ discrete: width = 1280, height = 720 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 180 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 352, height = 288 }
Time interval between frame: 1/30,
{ discrete: width = 424, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 360 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 480 }
Time interval between frame: 1/30,
{ discrete: width = 848, height = 480 }
Time interval between frame: 1/30,
{ discrete: width = 960, height = 540 }
Time interval between frame: 1/30,
{ pixelformat = 'YUYV', description = 'YUYV 4:2:2' }
{ discrete: width = 640, height = 480 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 180 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 352, height = 288 }
Time interval between frame: 1/30,
{ discrete: width = 424, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 360 }
Time interval between frame: 1/30,
{ discrete: width = 848, height = 480 }
Time interval between frame: 1/20,
{ discrete: width = 960, height = 540 }
Time interval between frame: 1/15,
{ discrete: width = 1280, height = 720 }
Time interval between frame: 1/10,
{ pixelformat = 'RGB3', description = 'RGB3' }
{ discrete: width = 1280, height = 720 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 180 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 352, height = 288 }
Time interval between frame: 1/30,
{ discrete: width = 424, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 360 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 480 }
Time interval between frame: 1/30,
{ discrete: width = 848, height = 480 }
Time interval between frame: 1/20,
{ discrete: width = 960, height = 540 }
Time interval between frame: 1/30,
{ pixelformat = 'BGR3', description = 'BGR3' }
{ discrete: width = 1280, height = 720 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 180 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 352, height = 288 }
Time interval between frame: 1/30,
{ discrete: width = 424, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 360 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 480 }
Time interval between frame: 1/30,
{ discrete: width = 848, height = 480 }
Time interval between frame: 1/20,
{ discrete: width = 960, height = 540 }
Time interval between frame: 1/30,
{ pixelformat = 'YU12', description = 'YU12' }
{ discrete: width = 1280, height = 720 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 180 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 352, height = 288 }
Time interval between frame: 1/30,
{ discrete: width = 424, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 360 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 480 }
Time interval between frame: 1/30,
{ discrete: width = 848, height = 480 }
Time interval between frame: 1/20,
{ discrete: width = 960, height = 540 }
Time interval between frame: 1/30,
{ pixelformat = 'YV12', description = 'YV12' }
{ discrete: width = 1280, height = 720 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 180 }
Time interval between frame: 1/30,
{ discrete: width = 320, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 352, height = 288 }
Time interval between frame: 1/30,
{ discrete: width = 424, height = 240 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 360 }
Time interval between frame: 1/30,
{ discrete: width = 640, height = 480 }
Time interval between frame: 1/30,
{ discrete: width = 848, height = 480 }
Time interval between frame: 1/20,
{ discrete: width = 960, height = 540 }
Time interval between frame: 1/30,ffplay -f video4linux2 -framerate 60 -video_size 1920x1080 -pixel_format mjpeg -i /dev/video4用mjpeg的方式播放，并设置帧率。
如果你想把其他的raw流放入/dev/video设备中，也是可以用ffmpeg推流的：
ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0以上把屏幕推流到/dev/video0上，但video0是必须是虚拟设备，不对应实际device
同时一个device可以对应多个输入源，比如/dev/video0可以对应两个输入源通道，也就是它在硬件上可以对应两个usb输入口，用下面代码切换通道，-d 2代表指定/dev/video2
v4l2-ctl -d 2 -i 4查看驱动各种信息，如色域等，色域一般为Rec. 709，这个在笔者其他博客有介绍，-d 2指定usb设备
v4l2-ctl -DVI --get-parm -d 2
Driver Info:
Driver name : uvcvideo
Card type : USB Video: USB Video
Bus info : usb-0000:00:14.0-3.1
Driver version : 5.19.0
Capabilities : 0x84a00001
Video Capture
Metadata Capture
Streaming
Extended Pix Format
Device Capabilities
Device Caps : 0x04200001
Video Capture
Streaming
Extended Pix Format
Media Driver Info:
Driver name : uvcvideo
Model : USB Video: USB Video
Serial :
Bus info : usb-0000:00:14.0-3.1
Media version : 5.19.0
Hardware revision: 0x00002100 (8448)
Driver version : 5.19.0
Interface Info:
ID : 0x03000002
Type : V4L Video
Entity Info:
ID : 0x00000001 (1)
Name : USB Video: USB Video
Function : V4L2 I/O
Flags : default
Pad 0x01000007 : 0: Sink
Link 0x0200000d: from remote pad 0x100000a of entity 'Processing 2' (Video Pixel Formatter): Data, Enabled, Immutable
Video input : 0 (Camera 1: ok)
Format Video Capture:
Width/Height : 1920/1080
Pixel Format : 'MJPG' (Motion-JPEG)
Field : None
Bytes per Line : 0
Size Image : 4147200
Colorspace : sRGB
Transfer Function : Rec. 709
YCbCr/HSV Encoding: ITU-R 601
Quantization : Default (maps to Full Range)
Flags :
Streaming Parameters Video Capture:
Capabilities : timeperframe
Frames per second: 30.000 (30/1)
Read buffers : 0补充：
ffmpeg的libavdevice模块支持的计算机中常用的音视频捕获或输出设备：ALSA、AUDIO_BEOS 、JACK、OSS、1394、VFW等。
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