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据说人眼在观察景物时,光信号传人大脑神经,需经过一段短暂的时间,光的作用结束后,视觉形象并不立即消失,这种残留的视觉称“后像”,视觉的这一现象则被称为“视觉暂留”。也就是说,只要1s内变动24帧甚至更多的图片,就可以达到动画的效果,加上音频伴奏就是视屏了!!!
UVC摄像头+驱动+JPEG图库+mjpeg-streamer+HTML 完成了对用户远程提供视屏展示的服务。首先底层通过摄像头采集图片,通过驱动将数据流存储到JPEG图库,最终通过html交给用户的浏览器来解析,而mjpeg-streamer用来实现对这一流程的的控制。构成mjpeg-streamer视频流服务器。
MJPEG全名为 "Motion Joint Photographic Experts Group",是一种视频编码格式,
Motion JPEG技术常用与闭合电路的电视摄像机的模拟视频信号“翻译”成视频流,并存储在硬盘上。
典型的应用如数字视频记录器等。MJPEG不像MPEG,不使用帧间编码,因此用一个非线性编辑器就很容易编辑。
MJPEG的压缩算法与MPEG一脉相承,功能很强大,能发送高质图片,生成完全动画视频等;从另一个角度说,在某些条件下,MJPEG也许是效率最低的编码/解码器之一。
MJPEG与MJPG的区别:
那什么 USB 摄像头适合我们这一章的教程呢?这里有几个关键字: 支持UVC(免驱);YUV 或者 MJPEG 格式输出
免驱动摄像头,是一种遵循视频设备类(USB Video Class,简称UVC)标准协议的摄像头产品。将符合标准的摄像头连接到符合标准的操作系统,系统就会自动为其安装驱动并进行设置,使摄像头实现真正意义上的即插即用。
uvc是一种硬件的框架结构,只有当其是通过一种标准的设计使其实现了免驱;而V4L2是一种驱动程序,其是实现系统与uvc设备等的通信。
https://blog.csdn.net/codectq/article/details/44451237#commentBox
确定 USB 摄像头支持 UVC (在 PC 上)
root@linux:~# dmesg
[82693.612396] uvcvideo: Found UVC 1.00 device USB2.0 PC CAMERA (1908:2311)
[82693.616323] input: USB2.0 PC CAMERA as /devices/pci0000:00/0000:00:15.0/0000:03:00.0/usb3/3-2/3-2:1.0/input/input6
[82693.618370] usbcore: registered new interface driver uvcvideo
[82693.618373] USB Video Class driver (1.1.1)
VID:PID 是057e:030a 是 (1908:2311),在UVC 官方的文档中进一步确定是否被支持
http://www.ideasonboard.org/uvc/
OK!!
(1)确保USB摄像头在Ubuntu中被识别,查看设备节点 /dev/video*
root@linux:~# ls /dev/video*
/dev/video0
(2)安装并使用 xawtv 测试
root@linux:~# apt-get install xawtv
root@linux:~# xawtv /dev/video0
This is xawtv-3.103, running on Linux/i686 (4.4.0-31-generic)
xinerama 0: 1362x616+0+0
vid-open-auto: using grabber/webcam device /dev/video0
v4l2: oops: select timeout
OK!!!
内核选配 添加驱动支持USB储存设备
root@linux:linux-3.14-fs4412# make menuconfig
Device Drivers --->
[*] USB support --->
<*> EHCI HCD (USB 2.0) support
<*> EHCI support for Samsung S5P/EXYNOS SoC Series
<*> USB Mass Storage support
<*> USB3503 HSIC to USB20 Driver
USB Physical Layer drivers --->
<*> Samsung USB 2.0 PHY controller Driver
SCSI device support --->
<*> SCSI device support
<*> SCSI disk support
Device Drivers --->
<*> Multimedia support --->
--- Multimedia support
*** Multimedia core support ***
[*] Cameras/video grabbers support
[ ] Analog TV support (NEW)
[ ] Digital TV support (NEW)
[ ] AM/FM radio receivers/transmitters support (NEW)
[ ] Remote Controller support (NEW)
[*] Media Controller API
[*] V4L2 sub-device userspace API
[ ] Enable advanced debug functionality on V4L2 drivers (NEW)
[ ] Enable old-style fixed minor ranges on drivers/video devices (NEW)
*** Media drivers ***
[*] Media USB Adapters --->
[*] V4L platform devices --->
Device Drivers --->
<*> Multimedia support --->
<*>Media USB Adapters --->
--- Media USB Adapters
*** Webcam devices ***
<*> USB Video Class (UVC)
[*] UVC input events device support (NEW)
<*> GSPCA based webcams --->
< > USB Philips Cameras (NEW)
<*> CPiA2 Video For Linux
< > USB ZR364XX Camera support (NEW)
< > USB Syntek DC1125 Camera support (NEW)
< > USB Sensoray 2255 video capture device (NEW)
< > USBTV007 video capture support (NEW)
*** Webcam, TV (analog/digital) USB devices ***
< > Empia EM28xx USB devices support (NEW)
Device Drivers --->
<*> Multimedia support --->
<*>V4L platform devices --->
< > STV0680 USB Camera Driver (NEW)
< > SUNPLUS USB Camera Driver (NEW)
< > T613 (JPEG Compliance) USB Camera Driver (NEW)
< > TOPRO USB Camera Driver (NEW)
< > TV8532 USB Camera Driver (NEW)
< > VC032X USB Camera Driver (NEW)
< > ViCam USB Camera Driver (NEW)
< > Xirlink C-It USB Camera Driver (NEW)
<*> ZC3XX USB Camera Driver
Device Drivers --->
<*> Multimedia support --->
<*>V4L platform devices --->
--- V4L platform devices
<*> Support for timberdale Video In/LogiWIN
<*> SoC camera support
<*> platform camera support
< > R-Car Video Input (VIN) support (NEW)
< > SuperH Mobile MIPI CSI-2 Interface driver (NEW)
< > SuperH Mobile CEU Interface driver (NEW)
[ ] Samsung S5P/EXYNOS4 SoC series Camera Subsystem driver (NEW)
编译内核并cp到tftp根目录下
root@linux:linux-3.14-fs4412# make uImage
Image Name: Linux-3.14.0
Created: Thu Dec 6 01:18:21 2018
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 3178872 Bytes = 3104.37 kB = 3.03 MB
Load Address: 40008000
Entry Point: 40008000
Image arch/arm/boot/uImage is ready
root@linux:linux-3.14-fs4412# cp ./arch/arm/boot/uImage /tftpboot/uImage
mjpg-stream的移植需要jpeg的库,所以我们先移植jpeg的库
1.下载源码
http://mjpg-streamer.svn.sourceforge.net/viewvc/mjpg-streamer/
2.解压
root@linux:dev_test# ls
jpegsrc.v8b.tar.gz
root@linux:dev_test# tar -xvf jpegsrc.v8b.tar.gz
root@linux:dev_test# cd jpeg-8b/
3.配置编译
root@linux:jpeg-8b# mkdir -p /root/dev_test/mjpeg-streamer/video/jpegarm
root@linux:jpeg-8b# ./configure --prefix=/root/dev_test/mjpeg-streamer/video/jpegarm --host=arm-none-linux-gnueabi
root@linux:jpeg-8b# make
root@linux:jpeg-8b# make install
root@linux:jpeg-8b# ls -al /root/dev_test/mjpeg-streamer/video/jpegarm/lib/
total 2312
drwxr-xr-x 2 root root 4096 Dec 6 06:37 .
drwxr-xr-x 6 root root 4096 Dec 6 06:37 ..
-rw-r--r-- 1 root root 1432698 Dec 6 06:37 libjpeg.a
-rwxr-xr-x 1 root root 953 Dec 6 06:37 libjpeg.la
lrwxrwxrwx 1 root root 16 Dec 6 06:37 libjpeg.so -> libjpeg.so.8.0.2
lrwxrwxrwx 1 root root 16 Dec 6 06:37 libjpeg.so.8 -> libjpeg.so.8.0.2
-rwxr-xr-x 1 root root 919895 Dec 6 06:37 libjpeg.so.8.0.2
4.将jpeg库cp到nfs根目录下
root@linux:jpeg-8b# cp /root/dev_test/mjpeg-streamer/video/jpegarm/lib/* /nfs/rootfs/lib/
1.下载源码
官网:https://sourceforge.net/projects/mjpg-streamer/
root@linux:dev_test# svn checkout https://svn.code.sf.net/p/mjpg-streamer/code/ mjpg-streamer-code
root@linux:mjpg-streamer-code# tree -L 1 ./mjpg-streamer-code/
├── doc
├── mjpeg-client #分别有 linux和windows 的客户端
├── mjpg-streamer #目录下提供了 的执行程序和各个输入输出设备组件
├── mjpg-streamer-experimental
├── udp_client
└── uvc-streamer #目录下提供了 uvc-streamer的可执行目录
6 directories, 0 files
.
2.修改源码
root@linux:dev_test# cd ./mjpg-streamer-code/mjpg-streamer
root@linux:mjpg-streamer# pwd
/root/dev_test/mjpg-streamer-code/mjpg-streamer
root@linux:mjpg-streamer# vim ./plugins/input_uvc/Makefile
14 #CFLAGS += -O1 -DLINUX -D_GNU_SOURCE -Wall -shared -fPIC
15 CFLAGS += -O1 -DLINUX -D_GNU_SOURCE -Wall -shared -fPIC -I /root/dev_test/mjpeg-streamer/video/jpegarm/include
33 #$(CC) $(CFLAGS) -o $@ input_uvc.c v4l2uvc.lo jpeg_utils.lo dynctrl.lo $(LFLAGS)
34 $(CC) $(CFLAGS) -L /root/dev_test/mjpeg-streamer/video/jpegarm/lib/ -o $@ input_uvc.c v4l2uvc.lo jpeg_utils.lo dynctrl.lo $(LFLAGS)
3.编译生成*.so文件和可执行文件mjpg_streamr
root@linux:mjpg-streamer# make CC=arm-none-linux-gnueabi-gcc
root@linux:mjpg-streamer# ls *.so
input_file.so input_testpicture.so input_uvc.so output_file.so output_http.so output_udp.so
root@linux:mjpg-streamer# ls mjpg_streamer
mjpg_streamer
4.将前面编译生成文件,还有start.sh ./www/ 搬移到nfs根目录中
root@linux:mjpg-streamer# mkdir /nfs/rootfs/mjpg-streamer
root@linux:mjpg-streamer# cp -raf *.so /nfs/rootfs/mjpg-streamer/
root@linux:mjpg-streamer# cp -raf mjpg_streamer /nfs/rootfs/mjpg-streamer/
root@linux:mjpg-streamer# cp -raf start.sh www/ /nfs/rootfs/mjpg-streamer/
5.测试(开发板)
[root@farsight ]# cd boa
[root@farsight boa]# ls
boa boa.conf.back cgi-bin mime.types
boa.conf boa_indexer log www
[root@farsight boa]# ./boa
[root@farsight boa]# cd ../mjpg-streamer/
[root@farsight mjpg-streamer]# ./start.sh
将对服务器url请求,IP配置为服务器的IP地址,这里是192.168.9.9
摄像头
摄像头
![](http://192.168.9.9:8080/?action=stream)
最终实现
在我预料中的效果是这样的
然而实际效果却是这样的(捂脸)
可能是角度问题吧~~~
错误总结
问题:第一次运行发现页面没有图像显示,确定html文件中的ip地址是目标机
原因:市面上大部分摄像头都是支持YUV的,而不是JPEG的。
解决方法:由于mjpg-stream支持JPEG和YUV两种格式,所以只需修改start.sh,在输入中加入 ” - y “
假如原来是./mjpg_streamer -i “./input_uvc.so ” -o “./output_http.so -w ./www”,则改为
./mjpg_streamer -i “./input_uvc.so -y” -o “./output_http.so -w ./www”即可。
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