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Wireless webcam with .NET Micro


#1

Hi,

I like to create a wireless webcam with a board of GHI purely in netmf. I know netmf is not so realtime that it can handle video. But if I pass it directly to another device by wifi would it be possible then? So eg create a memorystream and pass it forward to a networkstream.

If it is possible, wich specs should I have?

Roel


#2

You can use FEZ Cobra (EMX) with IP cameras


#3

Thanks for your reply!

I think I should be more clear.

The camera should be connected to eg Cobra with a WiFi module. The device should send it over WiFi to a PC.

Still possible?

Roel


#4

Why not just use a WiFi camera and connected directly to PC?


#5

I like to make my own firmware as a project and customize it the way I like and can integrate it in desktopsoftware with no much issues.

I like making something like this for my robot just to be busy :slight_smile:

http://osbots.com/shop/product/srv-stereo-vision-system-svs/


#6

@ Roel. I think what Gus is saying is, there is no reason to pipe the stream via the fez - just to use cycles. You have two wifi streams. One the fez control channel (i.e. tilt/pan, on/off, commands, etc) and two a video wifi stream from the wifi video camera. From the pc, you would have comm port for fez and second using a .Net video library (e.g. TVideoGrabber, mitov) to display/capture the video in a media control. Leveraging a single wifi channel would be nice, but not sure a good use of the fez cycles and not sure it could keep up - unless only reason for fez.

If you want a challenge, make a hw/sw wifi solution with an integrated web cam and transmiter pair (use std hw compression, etc) and a wifi/usb receiver on the pc with a simple library/UI control to make a bone-simple commodity solution. While you are at it. Mux the video wifi channel with a control channel and expose Com ports on both sides. The device can leverage that port for control channel. Many takers (including me) out there I would think.


#7

Use a wifi based IP camera, or wireless (analogue) video transmitter/receiver.

Sending the video though the FEZ would still require you to decode it, unless you already had it as a binary stream. You can’t just read an analogue input into a memory stream - what would you be putting into the RAM?


#8

At the moment I have an anolog transmitter and receiver and it is already in the control panel. So that step is taken. Now I am looking for a step further.

The starting point would be a camera with a digital out. So no decoding, if it can’t be digital, I like to do hardware decoding. At the moment my experience in .NET and .NETMF are not that high, I can encode and decode video signals. I also think this will demand a lot of resources Fez could not handle. I am thinking about something like this: http://www.sparkfun.com/products/10061

Any doubts about specs and .NETMF to do the trick? I have read on the internet .NETMF and cobra is not capable of doing this…

Roel


#9

NETMF is not the problem, video decoding needs a lot of RAM. See this video on how ChipworkX is playing video back…this is a NETMF device http://www.microframeworkprojects.com/index.php?title=RLP_Video_Playback

Now, you can still use that JPEG camera with our smallest device since you are not decoding the JPEG image but only reading it and storing on SD card or transferring it over the network.


#10

How about wireless RSA? Use some std hw and not have all encoding jaz?

http://www.sparkfun.com/products/8739
http://www.rangevideo.com/index.php?main_page=product_reviews_info&products_id=5&reviews_id=6&zenid=b393f71c4545a1b9a875cf6465e31601

This 2.4ghz Tx/Rx pair looks interesting also.
http://www.rangevideo.com/index.php?main_page=product_info&cPath=35_22&products_id=200&zenid=b393f71c4545a1b9a875cf6465e31601


#11

Hi WIlliam,

Yes, I was thinking that the same a while ago. I bought then this one:

Works like a charm and implemented in my control panel within 2 hours.

But I like to take it a step further. At the moment my signals go over ZigBee, Wireless RCA and going to be WiFi. I like to integrate all that to only Wifi with DPWS and networkstreams. But everyone is pulling me to the other side as it would be no good idea (maybe to difficult?):slight_smile:

Roel


#12

Roel, Keep in mind that 900mhz systems are not legal in most countries. There’s all sorts of interesting things like GSM mobile and Missile telemetry in that band.


#13

Roel, the reason people are saying this isn’t a good idea to do “all in one” on a non-specialised platform is all about the volume of data involved in video.

Say for instance you’re talking a 640*480 with an 8-bit grayscale image (ie 1 byte per pixel), that is 307,200 bytes per image, and then at say 10FPS (pretty slow really) that’s 3,072,000 bytes per second that you have to first aquire and then package and then transmit to the other side. They have to then recieve and unpackage and then store or display it.

For this kind of task, you need to use specialised hardware, and that’s why people will say just use a dedicated video sender solution :slight_smile:


#14

@ Mark I will keep that in mind!

@ Brett If there would be a dedicated system in .NETMF to do this, wich system should that be?

Roel


#15

ChipworkX can do video. It has 64MB of RAM and runs a 200Mhz processor

See wiki for project example


#16

ChipworkX can decode/play video, however it cannot [italic]capture[/italic] video, that requires separate hardware.

If you’re good with USB and have a USB analyser you can probably implement the USB video device class on chipworkx to use a simple (simpler the better) USB capture device. Something like a PixelView XCapture USB. Things with encoding on the stream will just make life harder.


#17

If your current solution is working, I assume you just want to remove the RX device and bulk and just have both data/video go into your pc wifi. Is that correct? I guess another potential solution without having to recreate the wheel is:

  1. Find a small wifi router (or rip the board out of one). Any two port wifi hubs around?
  2. Plug ethernet shield into 1 port wifi hub on device.
  3. Plug IP web cam into 2nd port on wifi hub.

Now both devices (data and video) use same hub on device. You could also just have a seperate wifi TX dedicated to IP web cam and just have two wifi’s on the device. In either case, the PC-side will just need one wifi. In this way, you get out of encoder business all togther and leverage existing solutions.