PXA 16x Plug USB Camera Demo Setup app note.fm
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1. operate more efficiently some USB webcams work better than others when transmitting high resolution or high frame rate video Experiment with different camera models and vendors to see which work best Web pages and video are served up by MJPG streamer s output_http so plug in The TCP port used by the web server is specified with the p option This demo keeps things simple by running the web server on port 80 the standard port for HTTP traffic It is entirely possible to run another web server alongside one or more instances of output_http so provided each is assigned a unique TCP port For instance a single ARMADA PXA 16x Plug Computer can be connected to four webcams and run four instances of MJPG streamer along with a secure lightweight front end web server like lighttpd All of the HTML CSS GIF PNG and Javascript files that comprise the demo web site along with the Cambozola Java video rendering applet are stored in the www subdirectory which is passed to the output_http so plug in with the w option Note that MJPG streamer can operate without a single page of HTML To obtain a snapshot specify the Plug Computer running MJPG streamer as the source in an lt img gt tag as follows lt img src http IP_ADDRESS OR HOSTNAME PORT NUMBER action snapshot gt Valid attributes for lt img gt can also be placed in this tag as the tag is rendered by the web browser and has no impact on the operation of MJPG streamer So2. the Plug has a live Internet connection is to download it directly with wget Ata command prompt see the Marvell ARMADA PXA 16x Plug Computer Development Kit User Manual for options enter wget http url of demo where url of demo is the URL of the demo tarball copied from the web browser and pasted into the terminal window for the sake of simplicity After downloading the demo install it as follows 2 Extract the files from the tarball with the following command tar xvjPf marvell mjpg streamer demo tar bz2 The P option is necessary to install the script that starts and stops the demo in etc init dand the symbolic link in etc rc5 d that launches the demo near the end of system boot If the P option is omitted the entire demonstration package is extracted to the working directory and the demo will not launch automatically when the system is rebooted 3 Mount the kernel partition Use mnt for the mount point as shown below if nothing is already mounted there or in a subdirectory below mnt mount dev mmcb1k0p1 mnt 4 Unless otherwise modified U Boot automatically loads the zlmage file to launch the boot sequence Rename the existing kernel to back it up with for example mv zImage previousZimage 5 Copy the kernel provided in the demo tarball to the kernel partition on the Plug microSDHC card cp marvell mjpg streamer demo kernel zImageDemo mnt zImage 6 Now unmount the kernel partition umoun
3. APPLICATION NOTE Marvell ARMADA PXA 16x Plug Computer USB Webcam MARVELL Streaming Internet Video Demo Setup A Purpose This document describes how to install and customize the USB Webcam Network Video Streaming Demonstration for the Marvell ARMADA PXA 16x Plug Computer The package archive consists of a Linux 2 6 29 kernel compiled with built in USB video class device support the video streamer web server program and a set of web pages that demonstrates how to display the video stream 2 Requirements The demo runs on the Marvell ARMADA PXA 16x Plug Computer and has been tested with versions 0 4 0 5 and 0 6 of the root file system In theory the demo should work with any USB web camera that complies with version 1 0 or later of the USB video class UVC Practical reality is such that some webcams purporting to be UVC devices do not work with the version of the Linux driver compiled into the kernel that is included with the demo package During development and testing of the demo two such webcams were identified a white box model based on a controller chip from Aveo VID PID 1871 0d01 and the Kodak Dual Webcam D101 VID PID 0ac8 3460 So having a few different candidates to try with the demo is prudent These cameras have been used successfully e Kodak Family HD Webcam VID PID 0603 8122 e Logitech HD Webcam C510 VID PID 046d 081d e Logitech QuickCam Fusion VID PID 046d 08ca e Logitech QuickCam
4. Orbit AF VID PID 046d 0994 e Logitech QuickCam UltraVision VID PID 046d 08c9 USB vendor ID VID and product ID PID are listed for the specific cameras tested with the demo A given webcam model may encompass multiple hardware revisions but each of these usually has a unique PID thus permitting differentiation Because this is a streaming video demonstration the Plug Computer must be connected to a network along with the PC used for browsing Although not required a live Internet connection facilitates downloading the demo tarball directly onto the Plug 3 Software and Licenses This demonstration is built entirely from open source software The packages used and their governing licenses are as follows Linux Kernel www kernel org GNU Public License version 2 GPLv2 Debian GNU Linux www debian org Various MJPG streamer mjpg streamer sf net GPLv2 Mollio CSS HTML Templates www mollio org GreyBox orangoo com labs GreyBox GNU Lesser General Public License v2 1 LGPL Cambozola www charliemouse com code cambozola GPLv2 Javascript rendering code by Richard Atterer in MJPG streamer GPLv2 http www marvell com Copyright May 2011 Marvell Doc No MV S302070 00 Rev Document Classification Public Page 1 I MARVELL ARMADA PXA 16x Plug Computer USB Webcam Streaming Internet Video Demo 4 Installation 1 Load the demo tarball onto the Plug Computer The easiest way to do this assuming
5. amer MJPG Streamer Version 2 0 is ats i ARA Using V4L2 device dev video0 Desired Resolution 640 x 480 Frames Per Second 15 Formate esne asust MJPEG Unable to set format Invalid argument Init v4L2 failed exit fatal i init _VideoIn failed Unfortunately there is no simple way to determine if MJPG streamer fails to launch because of a given webcam s lack of compatibility with some aspect of the UVC specification a shortcoming in the Linux 2 6 29 kernel UVC driver or some problem with MJPG streamer itself The best option is simply to try another USB webcam 5 Using the Demo Point a web browser to the IP address noted in Step 1 above The demo home page looks like that shown in Figure 1 Copyright May 2011 Marvell Doc No MV S302070 00 Rev Document Classification Public Page 3 gt ee pv ce ARMADA PXA 16x Plug Computer USB Webcam Streaming Internet Video Demo Figure 1 ARMADA PXA 16x Plug Computer Webcam Demo Home Page AA Marvell ARMADA 166 P e 10 69 130 228 ndex html ARMADA 168 Plug Computer Webcam Demo About this Demo Demo Snapshot Stream Java Javascript MARVELL Efficiently Serving Up Video with HTML and Linux This demonstration uses the open source MJPG streamer package running under Debian Linux on the ARMADA 168 Plug Computer to stream live video from a USB video class compliant web camera for rendering in a browser MJPG
6. h Javascript that then modifies the HTML code identified by a specific of lt div gt tag Doc No MV S302070 00 Rev Copyright May 2011 Marvell Page 6 Document Classification Public Matz ARMADA PXA 16x Plug Computer USB Webcam Streaming Internet Video Demo MARVELL Of course the Javascript rendering code provided in the MJPG streamer sample files and used in this demo works with all modern browsers and can be used as a kind of least common denominator Unfortunately even when interpreted by the fastest Javascript engines available it still cannot achieve the kind of frame rates possible with browser native MJPEG rendering or by the Cambozola Java applet Disclaimer No part of this document may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying and recording for any purpose without the express written permission of Marvell Marvell retains the right to make changes to this document at any time without notice Marvell makes no warranty of any kind expressed or implied with regard to any information contained in this document including but not limited to the implied warranties of merchantability or fitness for any particular purpose Further Marvell does not warrant the accuracy or completeness of the information text graphics or other items contained within this document Marvell products are not designed for use in life support equipment or applications that w
7. if MJPG streamer is running on port 8800 of the Plug Computer with IP address 10 69 130 228 and is configured to stream 640x480 frames the lt img gt tag used to generate a 160x120 thumbnail for another web server is lt img src http 10 69 130 228 8800 action snapshot style width 160px height 120px gt Use action strean in this tag to transmit video As noted above only Firefox and Google Chrome can continuously render a MJPEG stream With Internet Explorer or Opera video must be rendered with either Javascript code or the Cambozola Java applet See the javascript html and java html files for these techniques For Internet Explorer the video presentation method can be made transparent to the end user by using conditional comments to insert IE specific code when the HTML page is rendered Consider this fragment lt if IE gt lt applet code com charliemouse cambozola Viewer archive cambozola jar lt param name url value action stream gt lt applet gt lt endif gt lt if IE gt lt img src action stream gt lt endif gt On Internet Explorer the HTML engine ignores the lt img gt tag that refers to the stream action and instead loads the Cambozola Java applet to render video from MJPG streamer An option that is more complicated than Internet Explorer conditional comments but that handles a wider range of browsers is to interrogate the navigator userAgent or navigator product properties wit
8. ka Fastwriter Datacom Systems on Silicon Libertas Link Street NetGX PHYAdvantage Prestera Raising The Technology Bar The Technology Within Virtual Cable Tester and Yukon are registered trademarks of Marvell Ants AnyVoltage Discovery DSP Switcher Feroceon GalNet GalTis Horizon Marvell Makes It All Possible RADLAN UniMAC and VCT are trademarks of Marvell All other trademarks are the property of their respec tive owners Intel XScale is a trademark or registered trademark of Intel Corporation or its subsidiaries in the United States and other countries Marvell Semiconductor Inc 5488 Marvell Lane Santa Clara CA 95054 USA Tel 1 408 222 2500 Fax 1 408 752 9028 Email commsales marvell com www marvell com Doc No MV S302070 00 Rev CONFIDENTIAL Copyright May 2011 Marvell Page 7 Document Classification Public
9. m gt and lt input gt tags along with some associated Javascript used to send pan and tilt commands to the Logitech QuickCam Orbit AF The MJPG streamer program is started by the marvell mjpg streamer demo marvell mjpg streamer demo sh script This line includes all of the parameters necessary to reconfigure the demo for a different frame rate or size mjpg_ streamer input input_uvc so f 15 r 640x480 output output _http so p 80 w www amp Copyright May 2011 Marvell Doc No MV S302070 00 Rev Document Classification Public Page 5 ye MARVELL ARMADA PXA 16x Plug Computer USB Webcam Streaming Internet Video Demo The input _uvc so plug in is the module that MJPG streamer uses to acquire MJPEG video from a UVC compliant webcam The and r options specify the frame rate and resolution in this case 15 fps and 640x480 pixels respectively The r parameter can be an explicit frame size like 640x480 or a standard resolution term like QSIF QCIF CGA QVGA CIF VGA SVGA XGA or SXGA Smooth video streaming of almost any frame size is possible with proper frame rate and camera selection For example MJPG streamer running on the ARMADA PXA 16x Plug Computer can transmit 1600x896 5 fps video using the Logitech HD Webcam C510 even with the full Debian Linux desktop environment running For reasons that are not entirely clear perhaps certain camera controller ICs
10. ould cause a life threatening situation if any such products failed Do not use Marvell products in these types of equipment or applications With respect to the products described herein the user or recipient in the absence of appropriate U S government authorization agrees 1 Not to re export or release any such information consisting of technology software or source code controlled for national security reasons by the U S Export Control Regulations EAR to a national of EAR Country Groups D 1 or E 2 2 Not to export the direct product of such technology or such software to EAR Country Groups D 1 or E 2 if such technology or software and direct products thereof are controlled for national security reasons by the EAR and 3 In the case of technology controlled for national security reasons under the EAR where the direct product of the technology is a complete plant or component of a plant not to export to EAR Country Groups D 1 or E 2 the direct product of the plant or major component thereof if such direct product is controlled for national security reasons by the EAR or is subject to controls under the U S Munitions List USML At all times hereunder the recipient of any such information agrees that they shall be deemed to have manually signed this document in connection with their receipt of any such information Copyright 5 25 11 Marvell International Ltd All rights reserved Marvell the Marvell logo Moving Forward Faster Alas
11. streamer has its own internal web server that is easily configured via command line switch to use any suitable TCP port This allows it to run at the same time as a standard Linux oriented web server like Apache lighttpd or thttpd Minimizing Overhead with USB Video Class Devices Webcams that comply with the USB video class UVC are commonly available and preferred for embedded applications because they output Motion JPEG M JPEG video The camera controller IC perforrns the M JPEG encoding in hardware eliminating the need to do so in software on the embedded processor The video stream can be transmitted to a web browser using HTTP and unlike Flash or RTSP no plug in is needed MJPG streamer at Work The image displayed here was grabbed by the MJPG streamer input plug in The HTTP request contains the GET parameters action snapshot This requests one single picture from the image input To display another example just click on the picture To view the stream with any browser select Javascript or Java from the navigation bar at the top of the page Firefox and Google Chrome are able to render the M JPEG stream directly Click Stream to see this in action Microsoft Internet Explorer 8 and earlier version 9 was not tested and Opera 11 cannot do this Learn more about the MJPG streamer project B here Explanatory text on each web page covers the different ways in which the MJPEG video stream can be rendered in a browser In particular no
12. t mnt 7 The new kernel and demo are now installed Before rebooting to launch the demo take note of the Plug IP address ifconfig The output should look something like this eth0 Link encap Ethernet HWaddr fa d4 e0 00 32 bl inet addr 192 168 1 138 Bcast 192 168 1 255 Mask 255 255 0 0 UP BROADCAST RUNNING MULTICAST MTU 1500 Metric 1 RX packets 7940 errors 0 dropped 0 overruns 0 frame 0 Doc No MV S302070 00 Rev Copyright May 2011 Marvell Page 2 Document Classification Public ARMADA PXA 16x Plug Computer USB Webcam Streaming Internet Video Demo Setup TX packets 266 errors 0 dropped 0 overruns 0 carrier 0 collisions 0 txqueuelen 1000 RX bytes 585947 572 2 KiB TX bytes 50444 49 2 KiB Interrupt 22 8 Copy the Plug IP address ensure the USB webcam is connected and issue the reboot command reboot 9 When the Plug reboots the demo start up script is called and the following status message is output MJPG Streamer Version 2 0 iy Using V4L2 device dev video0 Desired Resolution 640 x 480 Frames Per Second 15 Formats sasana seit MJPEG www folder path www HTTP TCP ports 680 username password disabled commands enabled If the webcam has a status LED that lights when active it will be lit When the demo is started with a webcam that is not compatible with the built in USB video class driver an error occurs and displays in the status output from MJPG stre
13. te the inability of Internet Explorer and Opera to render MJPEG When using either of these browsers the Java or Javascript rendering method must be generally used When the demo is launched with a Logitech QuickCam Orbit AF connected to the Plug the simple example web pages include buttons to the control this webcam s motorized pan and tilt features see Figure 2 Doc No MV S302070 00 Rev Copyright May 2011 Marvell Page 4 Document Classification Public ARMADA PXA 16x Plug Computer USB Webcam Streaming Internet Video Demo Setup Figure 2 Logitech QuickCam Orbit Web Page AA 10 69 130 228 stream_sim e 10 69 130 228 stream_simple_control html cam Orbit AF Ultimate video calling freedom The top and bottom rows of buttons in Figure 2 control the webcam s tilt and pan features respectively The double arrows perform a full extent pan or tilt while the single arrows adjust the pan or tilt in five degree increments The X button in each row returns the pan or tilt to its center position Note that all directions are relative to the camera thus a user looking directly at the camera will see video to his her right when panning left and vice versa 6 Hacking the Demo Modifying the demo is very easy All of the web pages served up by MJPG streamer s internal web server are located in the marvell mjpg streamer demo www directory The files ending with control html include the HTML lt for
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