虚拟机使用pc摄像头

ffmpeg是音视频必备，笔者VX：YQW1163720468，ffmpeg群讨论。注：ffmpeg爱好者

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
如何设置虚拟/dev/video参考：https://www.cnblogs.com/xl2432/p/13501145.html

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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