I have a project to transmit video using wireless modems. One of the modem will be connected via ethernet to a PC and the other end will be connected to an ethernet camera. The modem connected to the ethernet camera will transmit to the modem connected to the PC over the air.
I have searched for the internet and found some ethernet based cameras , most of them seem to meet my requirements , but I would never know the knitty gritty details/shortcommings of the cameras untill i try them. Also all these cameras are black boxes with limited configurability. Are there any programmable ethernet cameras available?
About a year ago I evaluated a handful of IP-cameras for one of my customers, and we found quality varies a *lot* between brands.
If you want image quality, standard protocols, configurability, good documentation and support, and you have a few bucks to spare, go for the Axis brand.
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If you want to go cheap, with nonstandard protocols, IE6 support only, no documentation and horrible GUI applications (like this:
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choose any cheap taiwanese brand.
Siemens also has some high-quality stuff, but all using propriatery protocols for which you need their closed source libs for displaying or recording video.
There are wireless extenders for home audio/video applications.
There are video cameras intended for 10/100/1000baseT networks that are usually quite reliable.
I assume that your wireless Ethernet modem is intended to carry reliably ethernet data (i.e using retransmissions) and hence not in real time or with predictable throughput.
It appears that you are doing camera -- ethernet -- wireless -- ethernet -- PC in which case it is possible that the wireless modems might add an other protocol layer for reliable wireless transmission around the ethernet protocol (such as TCP/IP).
Since the wireless propagation delay or throughput is highly variable due to retransmissions, the transmitting modem will very quickly have a huge backlog of data, since the camera generates new data in real time, regardless if the modems can transfer in time to the other end. Do you expect to transfer compressed or uncompressed video data ?
If uncompressed, it might be better to use just UDP in the ethernet and turn off any retransmissions in the wireless modems and expect that some UDP-frames are lost and reconstruct the missing lines from previous pictures. You need some message frame sequence numbering to know what frames are lost. The data will be delivered in real time and no backlogs can occur.
I would not buy an Ethernet video camera from one vendor and the wireless modems from an other vendors, without proof that they will work together properly.
- Your best bet would be if you could find a 'product' that was known to be reflashable, in the tradition of customized firmware on wrt54g wifi gateways for example. I haven't heard of such, but it might exist.
- I know that there are manufacturer evaluation platforms that combine an ethernet-capable embedded processor with a camera. I think there's one for the analog device blackfin for example. These are intended to be the starting point for a product design effort so they are programmable, but they aren't intended to be used as the product, so they are serious money ($600 sticks in my mind).
- At those prices, cost wise a cheap laptop with built in web-cam, or a USB-capable miniPC or embedded board plus a USB web cam could be competitive on cost, though probably not on size. If you can get the USB webcam itself to output an appropriate reslution/bandwidth data stream, your embedded board might be able to just pass it on over the ethernet without doing any compression.
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