Can You Connect 1080p SDI Cameras Into A 720p HD SDI DVR?

Hi
Can one connect a 1080P SDI camera to a 720P DVR and still get acceptable recording performance?

I know that the answer should be 'yes' but am not sure of the technical implications here.

Obviously 1080P has a higher bitrate than 720P to start with.
Seeing that SDI DVRs do the decoding at the DVR end, it means that the DVR has to work hard and becomes more expensive as the channels rise.

However, if one has a 720P DVR and it receives a 1080P stream, does it just drop frames, or does it do the decoding and simply convert the 1080P stream to an internal 720P stream?

What are the reasons why one would not want to do this?

The cost of a 1080P DVR is quite a bit higher than a 720P DVR. However, there is little difference in cost between 720P and 1080P SDI cameras. So it makes sense for us to buy 1080P SDI cameras so that they can be connected to a range of DVRs

Thanks!


Lewis, have you tried yet? That would be the best bet.

If not, what is the model of the 720p DVR?

In my experience, with similar situations, if a DVR is expressly labelled as 720p, it will not support higher resolutions. It could be limited as price segmentation strategy or it could be that the encoding chipset simply cannot handle the extra load of encoding 1080p vs 720p cameras (that are basically twice the 'size'/pixels).

Btw, choose wisely on non IP HD offerings. We're bearish on HD SDI as they don't have much big name manufacturer support and they now face steep competition from Dahua HDCVI and Hikvision HDTVI.

Yes, we have tried it and it does work.

We tested it on 4 channels only but now want to move to a 16 channel system.

We are more interested in the technical reason why and why not this may or may not be a good idea.

Also what the risk issues are when we connect 1080P cams to a 720P DVR

We just don't want to embark on a technology mismatch that will come and bite us later.

As for the CVI and TVI platforms, yes we are aware of them. These are still vendor specific and none of the big players seem to have taken it up. We use SDI as a replacement for analogue as we can use the same cabling. Otherwise we use IP cameras.

It doesn't seem that the big buys have taken to CVI and TVI - our guess is that there is no margin in it and we doubt that we will see the top names lending support.

"As for the CVI and TVI platforms, yes we are aware of them. These are still vendor specific and none of the big players seem to have taken it up."

The problem we have with CVI and TVI is that it appears to have support in a small circle of manufacturers. Really, which manufaturer wants to invest in technology where they make $10 profit on a camera instead of $100. The new standards are reminiscent of the old VHS vs BETA days. It depends of who gains the most traction and big-name support.

As for Dahua and HIK, are they really world rated trendsetters that will not simply introduce a locked in technology only available from them?

Trouble is...how long will any of these last (CVI and TVI) before being superceded by yet another technology?

SDI may have peceived litttle support etc, but hell..there are a lot of diverse companies that make the stuff.

We may have a narrow perspective but why does it seem to us that comments on this forum plays down SDI as a poorly supported technology? On a recent visit to Chinese factories and trade shows, SDI was 'everywhere'!! In fact, it was so prolific that we had a wake-up call to take off our IP blinkers and consider SDI as a plug-in replacement for analogue system upgrades - which has worked well for us.

We are still primarily an IP CCTV house.

However, we have contact with a large number of Chinese manufaturers of cameras and DVR who sell boatloads of the SDI stuff.

Contrary to our perceived output of CVI and TVI products.

So what is going on? What are we missing?

Yes, SDI is more expensive, but we do not see the market penetration of an alternative.

Hopefully this thread may bring the debate to another level.

"SDI may have peceived litttle support etc, but hell..there are a lot of diverse companies that make the stuff."

Who are those companies? And how strongly committed are they? I don't know of any large manufacturer who is committed to HDSDI. Samsung has a token SDI offering, big analog players like Pelco, Honeywell, Bosch, etc. have none. Hik and Dahua have a little but both are moving away to their own offerings.

"However, we have contact with a large number of Chinese manufaturers of cameras and DVR who sell boatloads of the SDI stuff.

Contrary to our perceived output of CVI and TVI products."

SDI has been available for many years. CVI just came out in the last year. TVI just started shipping this summer (Hikvision literally this month). It won't take very long for CVI and TVI to far outstrip SDI sales - better products, lower price, bigger manufacturer support.

TVI is not from Hikvision, it's from Techpoint. CVI is from Dahua but there's already a lot of OEMs taking it up (FLIR, Q-See, Foscam, just to name a few bigger companies in the US).

"It depends of who gains the most traction and big-name support."

I totally agree with you about this. My points above is that CVI and TVI have much bigger named support behind, are going to get a lot more marketing and attention, plus since it's a lower cost, more feature rich offering, it will get a lot of traction quickly.

Hi John

We are not ardent supporters of SDI and hence appreciate a wider perspective from others. So, thanks for the input.

I am literaly just going on what our experience has been.

I can partly understand why analogue is the domain of the larger players you mention...they don't come cheap. Maybe in some places, but analogue from bigger players sure ain't cheap in our neck of the woods and this without the high quality that SDI offers. We were 'forced' to supply a 16-channel HIKVision analogue system to a client and our cost came in at $1200 from HIK distributor. So I guess the bigger names still make a buck from analogue and may see margins cut if they move to SDI and still want to be competitive.

Once companies move away to their own offerings, the market fragments and standards fall away. I guess that is why IP is still the intelligent choice. But then again...SDI came over the line and that isn't a standard. So there is hope for alternatives.

Interesting to note the US takeup...it would seem contrary from what we saw at the Chinese trade shows 6 months ago. We saw a proliferation of SDI and funnily...less IP.

Maybe it's a question of watching this space....

Are there any notable manufacturers for OEM in CVI that you are aware of? Likely from China? Ie manufacturers that are already shipping both DVR and cameras at 1080P? Or is Dahua the only one to your knowledge?

We would love to investigate.

Again, I may be mistaken, but on first appearances CVI would seem a better choice at this point...but then I also note that Dahua may be big but does not seem to enjouy a solid reputation in support services...appears more interested in pushing product and OEM.

HIK in our experience has been more interested in profiteering...so this is a hard one isn't it?

Lewis,

One thing I have seen is that Australian cctv prices seem to regularly be significantly higher than the US. Australians have mentioned this to us over the years for many products, IP, analog, VMSes, etc. I believe what you are saying. I am wondering if it's some sort of distribution issue / problem. For instance, Hikvision is extremely inexpensive in the US, across the board, and widely available.

"Are there any notable manufacturers for OEM in CVI that you are aware of?"

As I mentioned above - FLIR, Q-See, Foscam are some bigger names. And there are quite a number of no name brands from China.

Actually, the one we see the most from no name Chinese brands is AHD. They have no big name backers, and are 720p only now, so I think it's going to be tough for them. However, lots of low end Chinese manufacturers are promoting that.

Dahua overall is tough and depends on your region. In the US, there is essentially no sales nor support for integrators / dealers (unless you are an OEM) so it's a big big barrier. By contrast, Hikvision is now a well oiled sales and marketing machine in the US and that is helping them a lot.

Hi Lewis, I have a background in SDI having spent a decade with a manufacturer of SDI hardware. I haven't used SDI surveillance cameras but can tell you the following about HD-SDI.

A device which supports a maximum of 720p SDI on input won't magically downconvert a 1080p signal to 720p unless it is specifically designed (and advertized) to do so. I suppose it's possible someone might make a DVR which auto-detects a 1080p signal and downconverts it to 720p before recording it to storage. However there is nothing in the SMPTE standard for 720p SDI that will make this happen all by itself. It has to be a deliberate feature added in the hardware of the receiving device. One can purchase standalone converters which do this job for about US$500 per SDI signal which is worth contrasting with the price difference between a 720p and a 1080p capable DVR.

What may well be possible is that you might be able to set the SDI output of the 1080p camera to 720p if the camera includes a software or hardware switch. This should allow the 720p HD-SDI DVR to receive the camera signal without any problem. This would be my preferred solution if I wanted to use 1080p cameras with a 720p HD-SDI DVR. Furthermore it would cost you nothing.

Luke, yes after some research it would appear that the ability to automatically decode 1080P into 720P is totally dependant on the DVR vendor.

The answer aqppers to be YES, it is possible to connect a 1080P camera to a 720P DVR provided that the DVR manufaturer has built the front-end smarts into their box to convert the stream. There will also be a reduction of frame rate to make this work. There is also doubt whether any front-end decoding is spread accross all input channels.

So the answer is not a definitive yes or no, but rather a 'depends'....