I'm interested in capturing analog video in NTSC and transmitting it as efficiently as possible over a digital link, preferably while maintaining as much fidelity to the original signal as possible. My thought was that the video signal might be able to be sampled with a high-speed ADC, the samples transmitted, and the signal reconstructed at the other end with a DAC. Is this possible? If there's a better way of doing this, by all means share!

  • \$\begingroup\$ How far, how fast, and over what medium are you communicating? \$\endgroup\$ – tyblu Jan 25 '11 at 7:59
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    \$\begingroup\$ It's probably far wiser to extract the video from the NTSC modulation, encode it using something like h.264 or another streaming codec, and transmit it that way, converting back to NTSC at the other end. \$\endgroup\$ – Connor Wolf Jan 25 '11 at 8:33
  • \$\begingroup\$ @Fake Name: Are you aware of a piece of hardware which will let me pull the video from the NTSC signal in real time? \$\endgroup\$ – Nick Pascucci Jan 25 '11 at 20:39
  • \$\begingroup\$ Probably a really fast ADC and a FPGA? It's not trivial. \$\endgroup\$ – Connor Wolf Jan 28 '11 at 1:16
  • \$\begingroup\$ @Fake Name: It certainly isn't. I'm reading up on my CCDs; I may just build the camera myself. Thanks for your help! \$\endgroup\$ – Nick Pascucci Jan 28 '11 at 2:43

Yes it is possible 100%. A little inefficient due to blanking intervals but 100% possible. You should get some 50-100Mhz+ 8-12bit ADC + DAC on other side.

But transmitting 8x100Mhz signal might be a problem for long distance.

If you are really cool you may encapsulate it into 1G Ethernet :-D

  • \$\begingroup\$ Great, that's the first step. As I recall, the blanking interval makes up about 7% of the total transmission time. Perhaps I can use that to buffer the data transmission somewhat and improve the channel utilization. Thoughts? \$\endgroup\$ – Nick Pascucci Jan 25 '11 at 20:41
  • \$\begingroup\$ Any buffering would complicate your job alot (currently you can make it even without processor/FPGA). 7% loss is not much in fact. \$\endgroup\$ – BarsMonster Jan 25 '11 at 21:00

You may wish to look at a protocol called SDI, totally standard stuff in the broadcast world, but NTSC is about the worst possible place to start, even component would be a better starting point.

Video bandwidth for standard def is actually only about 6MHz tops, but broadcasters like to do much better for production even if it gets mangled by the transmit chain, so standard def SDI is 270Mb/s rising to 2.97Gb/s for high def.

To be honest nearly nobody bothers with analogue video these days, it is a pain in the toot in all ways, and 3Gb/s serdes are not the big deal they once were.

Regards, Dan.


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