查看“Mjpg-streamer”的源代码

=查看摄像头数据=
==列出所有摄像头设备==
:使用<code>v4l2-ctl --list-devices</code>命令来获取当前开发板下都有哪些摄像头设备，以及设备节点名称，如下所示我们使用的是USB摄像头对应的设备节点为<code>  /dev/video1</code>
<syntaxhighlight lang="bash">
[root@imx6ull:~]# v4l2-ctl --list-devices
pxp (pxp_v4l2):
        /dev/video0

USB 2.0 Camera (usb-ci_hdrc.1-1.3):
        /dev/video1
</syntaxhighlight>

==查看摄像头详细信息==
:使用<code> v4l2-ctl -L</code>命令来列出摄像头设备的详细信息，使用<code>-d /dev/video1</code>来指定查看的摄像头设备为/dev/video1
<syntaxhighlight lang="bash">
[root@imx6ull:~]#  v4l2-ctl -L -d /dev/video1
                     brightness 0x00980900 (int)    : min=-255 max=255 step=1 default=0 value=0
                       contrast 0x00980901 (int)    : min=0 max=30 step=1 default=15 value=15
                     saturation 0x00980902 (int)    : min=0 max=127 step=1 default=30 value=30
                            hue 0x00980903 (int)    : min=-16000 max=16000 step=100 default=0 value=0
 white_balance_temperature_auto 0x0098090c (bool)   : default=1 value=1
                          gamma 0x00980910 (int)    : min=20 max=250 step=1 default=98 value=98
           power_line_frequency 0x00980918 (menu)   : min=0 max=2 default=1 value=1
                                0: Disabled
                                1: 50 Hz
                                2: 60 Hz
      white_balance_temperature 0x0098091a (int)    : min=2500 max=7000 step=1 default=5000 value=5000 flags=inactive
                      sharpness 0x0098091b (int)    : min=0 max=15 step=1 default=2 value=2
         backlight_compensation 0x0098091c (int)    : min=0 max=2 step=1 default=1 value=1
</syntaxhighlight>

==查看摄像头支持的像素格式和分辨率==
:使用<code>v4l2-ctl --list-formats-ext</code>命令来获取列出摄像头支持的像素格式，分辨率大小，以及帧率都有哪些，使用<code> -d /dev/video1</code>命令来指定获取的设备为<code>/dev/video1</code>。
<syntaxhighlight lang="bash">		 
[root@imx6ull:~]#
 v4l2-ctl --list-formats-ext -d /dev/video1
ioctl: VIDIOC_ENUM_FMT
        Type: Video Capture

        [0]: 'YUYV' (YUYV 4:2:2)
                Size: Discrete 640x480
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 160x120
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 320x240
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 352x288
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 800x600
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1280x1024
                        Interval: Discrete 0.083s (12.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1600x1200
                        Interval: Discrete 0.111s (9.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
        [1]: 'MJPG' (Motion-JPEG, compressed)
                Size: Discrete 640x480
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 160x120
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 320x240
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 352x288
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 800x600
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1280x1024
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)

</syntaxhighlight>

=使用mjpg_streamer预览摄像头数据=
==查看开发板IP地址==
<syntaxhighlight lang="bash">
[root@imx6ull:~]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:01:3F:2D:3E:4D
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

eth1      Link encap:Ethernet  HWaddr 00:01:1F:2D:3E:4D
          inet addr:192.168.1.21  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fdfd:3597:aa7a:0:201:1fff:fe2d:3e4d/64 Scope:Global
          inet6 addr: fe80::201:1fff:fe2d:3e4d/64 Scope:Link
          inet6 addr: fdfd:3597:aa7a::914/64 Scope:Global
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:558 errors:0 dropped:0 overruns:0 frame:0
          TX packets:291 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:221870 (216.6 KiB)  TX bytes:29419 (28.7 KiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:7756 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7756 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1
          RX bytes:468263 (457.2 KiB)  TX bytes:468263 (457.2 KiB)
</syntaxhighlight>
==mjpg_streamer参数讲解==
:使用mjpg_streamer -h 查看帮助信息。
<syntaxhighlight lang="bash">
[root@imx6ull:~]# mjpg_streamer -h
-----------------------------------------------------------------------
Usage: mjpg_streamer
  -i | --input "<input-plugin.so> [parameters]"
  -o | --output "<output-plugin.so> [parameters]"
 [-h | --help ]........: display this help
 [-v | --version ].....: display version information
 [-b | --background]...: fork to the background, daemon mode
-----------------------------------------------------------------------
Example #1:
 To open an UVC webcam "/dev/video1" and stream it via HTTP:
  mjpg_streamer -i "input_uvc.so -d /dev/video1" -o "output_http.so"
-----------------------------------------------------------------------
Example #2:
 To open an UVC webcam and stream via HTTP port 8090:
  mjpg_streamer -i "input_uvc.so" -o "output_http.so -p 8090"
-----------------------------------------------------------------------
Example #3:
 To get help for a certain input plugin:
  mjpg_streamer -i "input_uvc.so --help"
-----------------------------------------------------------------------
In case the modules (=plugins) can not be found:
 * Set the default search path for the modules with:
   export LD_LIBRARY_PATH=/path/to/plugins,
 * or put the plugins into the "/lib/" or "/usr/lib" folder,
 * or instead of just providing the plugin file name, use a complete
   path and filename:
   mjpg_streamer -i "/path/to/modules/input_uvc.so"
-----------------------------------------------------------------------
</syntaxhighlight>
:得知mjpg_streamer后需要接-i和-o两个参数，再分别看这两个参数提供的不同so插件文件支持哪些选项。
:可选的-h查询帮助信息、-v查询版本信息、-b后台执行就不多介绍了。
:输入so插件包含：input_uvc.so、input_testpicture.so、(input_file.so、input_ptp2.so、input_http.so)
:输出so插件包含：output_http.so、(output_file.so、output_udp.so、output_rtsp.so、output_viewer.so)
:其中括号部分，我这个Buildroot的mjpg_streamer版本没有提供。

=== 输入插件1：input_uvc.so===
<syntaxhighlight lang="bash">
# mjpg_streamer -i "/usr/lib/input_uvc.so --help"
MJPG Streamer Version: git rev: fd184d0
---------------------------------------------------------------
Help for input plugin..: UVC webcam grabber
---------------------------------------------------------------
The following parameters can be passed to this plugin:
[-d | --device ].......: video device to open (your camera)
[-r | --resolution ]...: the resolution of the video device,
                        can be one of the following strings:
                        QQVGA QCIF CGA QVGA CIF PAL
                        VGA SVGA XGA HD SXGA UXGA
                        FHD
                        or a custom value like the following
                        example: 640x480
[-f | --fps ]..........: frames per second
                        (activates YUYV format, disables MJPEG)
[-q | --quality ] .....: set quality of JPEG encoding
[-m | --minimum_size ].: drop frames smaller then this limit, useful
                        if the webcam produces small-sized garbage frames
                        may happen under low light conditions
[-e | --every_frame ]..: drop all frames except numbered
[-n | --no_dynctrl ]...: do not initalize dynctrls of Linux-UVC driver
[-l | --led ]..........: switch the LED "on", "off", let it "blink" or leave
                        it up to the driver using the value "auto"
[-t | --tvnorm ] ......: set TV-Norm pal, ntsc or secam
[-u | --uyvy ] ........: Use UYVY format, default: MJPEG (uses more cpu power)
[-y | --yuv  ] ........: Use YUV format, default: MJPEG (uses more cpu power)
[-fourcc ] ............: Use FOURCC codec 'argopt',
                        currently supported codecs are: RGBP
---------------------------------------------------------------
Optional parameters (may not be supported by all cameras):
[-br ].................: Set image brightness (auto or integer)
[-co ].................: Set image contrast (integer)
[-sh ].................: Set image sharpness (integer)
[-sa ].................: Set image saturation (integer)
[-cb ].................: Set color balance (auto or integer)
[-wb ].................: Set white balance (auto or integer)
[-ex ].................: Set exposure (auto, shutter-priority, aperature-priority, or integer)
[-bk ].................: Set backlight compensation (integer)
[-rot ]................: Set image rotation (0-359)
[-hf ].................: Set horizontal flip (true/false)
[-vf ].................: Set vertical flip (true/false)
[-pl ].................: Set power line filter (disabled, 50hz, 60hz, auto)
[-gain ]...............: Set gain (auto or integer)
[-cagc ]...............: Set chroma gain control (auto or integer)
---------------------------------------------------------------
input_init() return value signals to exit
</syntaxhighlight>
*基本参数：
:* -d：指定video设备节点
:* -r：指定分辨率，VGA或640x480类似值
:* -f：指定每秒帧数
:* -q：指定JPEG编码质量
:* -m：指定丢弃小于该值的帧
:* -e：删除除编号以外的所有帧
:* -n：不要初始化Linux-UVC驱动程序的dynctrls
:* -l：设置LED on/off/blink，设置auto将取决于驱动程序
:* -t：设置TV-Norm pal，ntsc或secam
:* -u：指定输入为UYVY格式，通过CPU将UYVC转为MJPEG，这样会消耗更多CPU
:* -y：指定输入为YUV格式，通过CPU将YUV转为MJPEG，这样会消耗更多CPU
:* -fourcc：使用FOURCC编解码器argopt，目前支持的编解码器是：RGBP
:* 新版新增：
:* -timestamp：使用系统时间填充帧时间戳
:* -softfps：丢帧以尝试实现此FPS
*图像参数：
:*-br：设置图像亮度
:*-co：设置图像对比度
:*-sh：设置图像清晰度
:*-sa：设置图像饱和度
:*-cb：设置图像颜色平衡
:*-wb：设置图像白平衡
:*-ex：设置图像曝光
:*-bk：设置图像曝光补偿
:*-rot：设置图像旋转0-359
:*-hf：设置图像水平翻转
:*-vf：设置图像垂直翻转
:*-pl：设置图像避免闪烁频率
:*-gain：设置图像增益
:*-cagc：设置图像色度增益控制


===输入插件2：input_testpicture.so===  	
<syntaxhighlight lang="bash">
# mjpg_streamer -i "/usr/lib/input_testpicture.so --help"
MJPG Streamer Version: git rev: fd184d0
 ---------------------------------------------------------------
 Help for input plugin..: TESTPICTURE input plugin
 ---------------------------------------------------------------
 The following parameters can be passed to this plugin:
 [-d | --delay ]........: delay to pause between frames
 [-r | --resolution]....: can be 960x720, 640x480, 320x240, 160x120
 ---------------------------------------------------------------
input_init() return value signals to exit
</syntaxhighlight>

*基本参数：
:*-d：指定在两帧之间的延时
:*-r：指定在分辨率

===输入插件3：input_file.so===


	
<syntaxhighlight lang="bash">
# mjpg-streamer -i "/snap/mjpg-streamer/42/lib/mjpg-streamer/input_file.so --help"
MJPG Streamer Version: git rev: f387bb44e6c087271b763b27da998bf2e06c4f5d
 ---------------------------------------------------------------
 Help for input plugin..: FILE input plugin
 ---------------------------------------------------------------
 The following parameters can be passed to this plugin:
 [-d | --delay ]........: delay (in seconds) to pause between frames
 [-f | --folder ].......: folder to watch for new JPEG files
 [-r | --remove ].......: remove/delete JPEG file after reading
 [-n | --name ].........: ignore changes unless filename matches
 [-e | --existing ].....: serve the existing *.jpg files from the specified directory
 ---------------------------------------------------------------
input_init() return value signals to exit
</syntaxhighlight>
*基本参数：
:*-d：指定在两帧之间的延时(单位:s)
:*-f：指定查看新JEPG文件的目录
:*-r：指定读取后要删除的JEPG文件
:*-n：指定除非文件名匹配忽略更改
:*-e：指定目录读取现有JPG文件

===输入插件4：input_ptp2.so===
<syntaxhighlight lang="bash">
# mjpg-streamer -i "/snap/mjpg-streamer/42/lib/mjpg-streamer/input_ptp2.so --help"
MJPG Streamer Version: git rev: f387bb44e6c087271b763b27da998bf2e06c4f5d
PTP2 input plugin: invalid option -- '-'
 ---------------------------------------------------------------
 Help for input plugin..: PTP2 input plugin
 ---------------------------------------------------------------
 The following parameters can be passed to this plugin:
 [-h ]..........: print this help
 [-u X ]........: delay between frames in us (default 0)
 [-d X ]........: camera address in [usb:xxx,yyy] form; use
                  gphoto2 --auto-detect to get a list of
                  available cameras
 ---------------------------------------------------------------
input_init() return value signals to exit
</syntaxhighlight>
*基本参数：
:*-h：打印帮助
:*-u：指定在两帧之间的延时(单位:us)
:*-d：指定可用相机

===输入插件5：input_http.so===

<syntaxhighlight lang="bash">
# mjpg-streamer -i "/snap/mjpg-streamer/42/lib/mjpg-streamer/input_http.so --help""
MJPG Streamer Version: git rev: f387bb44e6c087271b763b27da998bf2e06c4f5d
 ---------------------------------------------------------------
 Help for input plugin..: HTTP Input plugin
 ---------------------------------------------------------------
 The following parameters can be passed to this plugin:
 [-v | --version ]........: current SVN Revision
 [-h | --help]............: show this message
 [-H | --host]............: select host to data from, localhost is default
 [-p | --port]............: port, defaults to 8080
 ---------------------------------------------------------------
input_init() return value signals to exit
</syntaxhighlight>
*基本参数：
:*-v：打印版本信息
:*-h：打印帮助信息
:*-H：指定主机地址
:*-p：指定端口

===输出插件1：output_http.so===
<syntaxhighlight lang="bash">	
# mjpg_streamer -o "/usr/lib/output_http.so --help"
MJPG Streamer Version: git rev: fd184d0
---------------------------------------------------------------
Help for output plugin..: HTTP output plugin
---------------------------------------------------------------
The following parameters can be passed to this plugin:
[-w | --www ]...........: folder that contains webpages in
                        flat hierarchy (no subfolders)
[-p | --port ]..........: TCP port for this HTTP server
[-l ] --listen ]........: Listen on Hostname / IP
[-c | --credentials ]...: ask for "username:password" on connect
[-n | --nocommands ]....: disable execution of commands
---------------------------------------------------------------
output_init() return value signals to exit
</syntaxhighlight>
*基本参数：
:*-w：指定网页根目录(不支持子文件夹)
:*-p：指定HTTP服务器的TCP端口
:*-l：指定监听主机IP
:*-c：指定在连接时询问的账户名、密码
:*-n：指定禁用命令执行

===输出插件2：output_file.so===

<syntaxhighlight lang="bash">
# mjpg-streamer -o "/snap/mjpg-streamer/42/lib/mjpg-streamer/output_file.so --help"
MJPG Streamer Version: git rev: f387bb44e6c087271b763b27da998bf2e06c4f5d
 ---------------------------------------------------------------
 Help for output plugin..: FILE output plugin
 ---------------------------------------------------------------
 The following parameters can be passed to this plugin:
 [-f | --folder ]........: folder to save pictures
 [-m | --mjpeg ].........: save the frames to an mjpg file 
 [-l | --link ]..........: link the last picture in ringbuffer as this fixed named file
 [-d | --delay ].........: delay after saving pictures in ms
 [-i | --input ].........: read frames from the specified input plugin
 The following arguments are takes effect only if the current mode is not MJPG
 [-s | --size ]..........: size of ring buffer (max number of pictures to hold)
 [-e | --exceed ]........: allow ringbuffer to exceed limit by this amount
 [-c | --command ].......: execute command after saving picture
 ---------------------------------------------------------------
output_init() return value signals to exit
</syntaxhighlight>
*基本参数：
:*-f：指定保存图片文件夹
:*-m：将帧保存的mjpg文件夹
:*-l：将ringbuffer中的最后一张图片链接为此固定命名文件
:*-d：保存图片后延时(单位:ms)
:*-i：从指定的输入插件中读取帧
*仅当当前模式不是MJPG时，以下参数才会生效
:*-s：环形缓冲区的大小（要保留的最大图片数）
:*-e：允许ringbuffer超过此数量的限制
:*-c：保存图片后执行命令

===输出插件3：output_udp.so===
<syntaxhighlight lang="bash">
# mjpg-streamer -o "/snap/mjpg-streamer/42/lib/mjpg-streamer/output_udp.so --help"
MJPG Streamer Version: git rev: f387bb44e6c087271b763b27da998bf2e06c4f5d
 ---------------------------------------------------------------
 Help for output plugin..: UDP output plugin
 ---------------------------------------------------------------
 The following parameters can be passed to this plugin:
 [-f | --folder ]........: folder to save pictures
 [-d | --delay ].........: delay after saving pictures in ms
 [-c | --command ].......: execute command after saveing picture
 [-p | --port ]..........: UDP port to listen for picture requests. UDP message is the filename to save
 [-i | --input ].......: read frames from the specified input plugin (first input plugin between the arguments is the 0th)
 ---------------------------------------------------------------
output_init() return value signals to exit
</syntaxhighlight>
*基本参数：
:*-f：指定保存图片的文件夹
:*-d：保存图片后延时(单位:ms)
:*-c：保存图片后执行命令
:*-p：指定UDP端口监听图片请求
:*-i：从指定的输入插件读取帧

===输出插件4：output_rtsp.so===

<syntaxhighlight lang="bash">
# mjpg-streamer -o "/snap/mjpg-streamer/42/lib/mjpg-streamer/output_rtsp.so --help"
MJPG Streamer Version: git rev: f387bb44e6c087271b763b27da998bf2e06c4f5d
 ---------------------------------------------------------------
 Help for output plugin..: RTSP output plugin
 ---------------------------------------------------------------
 The following parameters can be passed to this plugin:
 [-p | --port ]..........: UDP port to listen for picture requests. UDP message is the filename to save
 [-i | --input ].......: read frames from the specified input plugin (first input plugin between the arguments is the 0th)
 ---------------------------------------------------------------
output_init() return value signals to exit
</syntaxhighlight>
*基本参数：
:*-p：指定UDP端口监听图片请求
:*-i：从指定的输入插件读取帧

===输出插件5：output_viewer.so===

<syntaxhighlight lang="bash">
# mjpg-streamer -o "/snap/mjpg-streamer/42/lib/mjpg-streamer/output_viewer.so --help"
MJPG Streamer Version: git rev: f387bb44e6c087271b763b27da998bf2e06c4f5d
 ---------------------------------------------------------------
 Help for output plugin..: VIEWER output plugin
 ---------------------------------------------------------------
output_init() return value signals to exit
</syntaxhighlight>
*基本参数：
:*无
*参考页面 https://hceng.cn/2019/06/23/AM335X%E2%80%94%E2%80%94USB%E6%91%84%E5%83%8F%E5%A4%B4/#3-Web%E6%98%BE%E7%A4%BA

==执行mjpg_streamer获取摄像头数据==
:如下所示我们使用<code>-i</code>参数指定输入的摄像头数据类型为uvc类型，<code>-d</code>参数指定使用的摄像头设备为/dev/video1 ，<code>-r</code>参数指定输入分辨率为640x480 ，<code>-q</code>参数指定uvc数据质量为90，<code>-n</code>参数说明不要初始化Linux-UVC驱动程序的dynctrls，<code>-o</code>参数指定输出类型为http方式，<code>-w</code>指定网站目录为 /usr/share/mjpg-streamer/www/
 mjpg_streamer -i "/usr/lib/mjpg-streamer/input_uvc.so -d /dev/video1  -r 640x480 -f 30 -q 90 -n" -o "/usr/lib/mjpg-streamer/output_http.so -w /usr/share/mjpg-streamer/www/"

==浏览器打开并查看摄像头数据==
:如上所示我们的开发板IP地址为<code>192.168.1.21 </code>,让后我们使用电脑浏览器打开如下地址即可预览摄像头数据。
 192.168.1.21:8080