Do IP Cameras Require More Powerful Servers Than Analog?

Jon Honovich wrote in response to the previous blog post:

How does using megapixel cameras impact the total number of cameras
that an individual recorder can record?  The general answer is that
less cameras can be supported. Some manufacturers say this is an issue
with CPU utlilitization (when doing motion detection on the recorder),
others say this is an issue of limited i/o throughput.

Any input on this? I think it would make an interesting blog post. :)

Best,

John

--
IP Video Market Info
http://ipvideomarket.info

I am guessing that the short question everyone wants an answer to is this:
Does an IP-Only solution cost more than an Analog-Only solution? The answer is almost always YES, but there are a LOT of assumptions in that YES. It doesn't HAVE TO COST MORE.

To answer Jon's questions directly, let me give the short answers, followed by lengthy dissertation. (I know, I know, no one has time to read all this... but I'm writing it anyway.)

The maximum number of IP Cameras supported by a single Airship NVR is 32 at 640x480 at 30 fps.
The maximum number of Analog cameras supported by a single Airship DVR is 48 at 2CIF (704x240) at 30 fps OR 24 at 4CIF (704x480) at 30 fps.

There you have it - with current tech, Airship only goes up to 32 IP Cameras, as opposed to 48 Analog cameras. (WOW - there are A LOT of assumptions in that short answer... like the 2CIF vs. 4CIF detail)

The Airship NVR with 32 channels costs more than the Airship DVR with 32 channels, at that.

"Why?"
Because the Analog Encoders INSIDE the Airship DVR are more cost effective and provide more performance impact than most people would normally guess. Also, analog cameras are cheaper than quality-equal IP Cameras. Usually...

It's true that (for Airship) it takes more CPU, RAM, and GPU (video) resources to handle IP Cameras than Analog cameras require. But it doesn't necessarily affect costs of recording equipment. Let's write down some assumptions, to make the comparison fair:

A. Assume all video is 4CIF/30, both Analog and IP Cameras.
B. Assume identical video feeds.
C. Assume network bandwidth is NOT an issue at any point.

JUST GET THE VIDEO
In Airship, the same components that turn Analog video into digital video inside the Airship Server also render that video for display to the Server's VGA monitor. The CPU utilization for this is so trivial, that we literally don't even have to think about it. The dedicated H.264 Encoder Card does ALL the heavy work of encoding the video, rendering it for display, and sending it to the harddrives. Yes, the bits flow over the PCI bus, but that's just traffic, not computation.

To render the same video from an IP Camera, we have to decode the video for display, as well as send it to the harddrives for storage. That extra step of decoding the video must be handled by the CPU and GPU of the Server - there's no dedicated IP Camera Decoder in the Server.

To compare:

Analog

1. Airship Dedicated H.264 Encoder handles all video encoding, display, and storage operation.
2. CPU has a trivial load to direct traffic. (3% CPU utilization on a full operational 32 channel system is common.)
3. GPU has a trivial load to display video.

IP Camera

1. CPU responsible for IP Camera video decoding.
2. GPU helps with some of the video decoding/display.

"But, Gryph, how much CPU does an IP Camera use?"
Dear customer, that's a hard answer to give in a single sentence. Which IP Camera? You see, different IP Cameras use different video encoding, which vary in how hard they are to Decode by the Server.

ALSO - With Airship Servers, we turn the live view OFF on the Server by default because doing so frees up the Server CPU for more important work - like Motion Detection, hosting remote clients, and I/O operations. You CAN turn the live view of the IP Cameras on in a Stand-Alone Server operation, but we restrict the number of concurrent live views according to the Server's abilities. You know, it's almost like we think about it ahead of time... Anyway, we build the Airship Workstations to REALLY SHOW the video.

STORAGE
Now, let's talk about I/O - storing the Analog video to the hard drive vs. storing the IP Camera video to the hard drive.

Analog
In Airship, the dedicated H.264 Encoder results in a visually beautiful, yet small file size. This reduces the amount of I/O resources required. Other products vary, of course, but our 4CIF/30 video example seldom goes over 2Mbps. Compare that to MPEG4 or MPEG2 where comparable quality reaches up to 8Mbps.

IP Camera
This question depends on one important factor: What is the video stream bitrate?
IP Cameras come in many flavors of video encoding: MJPEG, MPEG4, H.264, even ol' wavelet (eek!) each of which will render the video in a "CERTAIN" bitrate.
BIG ASSUMPTION: IF the video stream bitrate is the SAME as the Analog example above (2Mbps), then the I/O performance should be the SAME.
HOWEVER: The efficiency of the NETWORK CHIPSET will have a big impact on overall efficiency of getting that IP Camera stream to the I/O subsystem in the first place.

Even if your server has a Gigabit Ethernet port, THEY ARE NOT ALL THE SAME. (Herein lies some of the magic sauce for Airship Servers, so I won't go into great detail... plus we assumed that network performance wasn't an issue above.) The best advice I can give is TESTING, TESTING, TESTING.

BOIL IT DOWN
DVR: The reason Analog Encoding seems 'cheaper' processing-wise is due to the use of Dedicated Encoding and Decoding hardware. This dedicated hardware ISN'T FREE. It's also not terribly expensive!

NVR: Building a Server capable of handling the IP Camera video we mentioned above is roughly cost-equivalent to the Analog solution. For high-channel counts, the NVR can cost more because the upgraded CPU and GPU actually cost more than the Dedicated Encoder.

Hybrid NVR/DVR: Hey, why not have it all? Costs a little more than just a DVR or just an NVR, but not as much as you'd guess. Stay flexible, impress your techie buddies at home...

In other words, Poh-Tay-Toh, Poh-Tah-Toh - IF THE VIDEO QUALITY IS EQUAL AND THE CHANNEL COUNT IS 16 OR UNDER.

What we haven't covered here:

Megapixel cameras - They Cost More - Money & Tech. Storing the larger video costs more. It takes more CPU and GPU to render the video. Higher network bandwidth requirements. Fewer channels per server, absolutely. (Wow, I really want to write in detail about this. Lemme know if you wanna hear it...)

Airship Workstations - They cost *differently*. An Airship Workstation can use Dedicated Decoders to render the Airship H.264 Encoded video - these are useless for IP Cameras. So, it takes CPU and GPU resources on the Workstation to render that video - just like on the Server. But those Dedicated Decoders cost something - they are not free. OVERALL, Workstations are more cost effective to build for large numbers of IP Cameras than they are for large numbers of Airship H.264 Encoded streams. BUT YOU CAN'T SKIMP ON COMPONENTS - And we don't, when you buy them from us. (See previous blogs about this.)

OK, that was a load of info - this is a loaded question with a load of details leading to loaded answers. My final word on this for now:
 
If ANYONE tries to give you a one sentence answer to this stuff without gathering detailed requirements first, they are MISSING SOMETHING. Or hiding something.

PS - A Sales Plug: Airship DOES ANALOG AND IP AT THE SAME TIME. Choose the solution that works for you today, knowing that you can choose to go a different route in the future and stick with the same Airship Enterprise Surveillance Suite.

by Gryphon MacThoy

Comments

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it's good to see this information in your post, i was looking the same but there was not any proper resource, thanx now i have the link which i was looking for my research.

[Gryphon MacThoy]

Hey Jon, another good question.

In short, Yes, compression type makes differences in capacity.

MPEG4 requires more network bandwidth, I/O capacity, and hard drive capacity. It is easier to decode to present to screen.

H.264 requires more CPU and GPU resources to deocde and present to the screen. It takes less network bandwidth, I/O capacity, and hard drive space.

That's a simple breakdown between the two, given equal video quality examples. The same idea applies to MJPEG - fatter stream, harder on network and storage, easier on decode.

The PC on your desk is only going to have so much CPU and GPU for rendering a bunch of H.264 streams simultaneously. It's also only going to have so much network bandwidth to those IP sources and only so much I/O capacity to store live streams or in some cases even get the video streams to the GPU for help in decoding. What's the tipping point? I dunno - it's a balancing act you HAVE to do for every application.

I hope we're helping with this dialog. BTW, I'm out traveling doing customer demos, so please have patience if I don't get back right away. - Thanks!

-G MacThoy

[Gryphon MacThoy]

Good question ckodish,

Direct answer to your last question:
16 would be the best guess. If you were to buy from us, we'd ask you what IP Camera you wanted to use and how and then design the most cost efficient NVR possible. We might even go out and buy your exact IP Camera to test with, or just borrow yours for a few weeks to optimize everything.

If you are looking at cameras like Cisco's HD stuff, then you are probably looking at megapixel cameras of much higher image resolutions than 4CIF or VGA (for easy comparison, I group these together as roughly the same, even though they are different).
Also, in your question, the major missing information is the video compression type. MPEG4, H.264?

So, where am I finding IP Cameras with a stream less than 2Mbps? Well, first of all, most any camera with resolution and frame rate settings can be set to low values that reduce the bitrate to near useless values (1 frame per minute, 1/4 VGA) but then again, we aren't saying what the video compression is.

HikVision makes a h.264 based 4CIF at 30 fps IP Camera that gets around 2Mbps. That's one example, and if they are the only ones I'd be surprised. The same video stream quality rendered in MPEG2, MPEG4 or MJPEG is going to be at least 4Mbps, on up.

Your 20fps video at 25Mbps is probably a GORGEOUS video to look at, by the way. 1080p HD? Higher?

Tips for more direct comparisons:
1 - Know the pixel counts h x w. VGA is 640x480. 4CIF is 704x480. Wikipedia has a great article about video format specifications here:

http://en.wikipedia.org/wiki/List_of_common_resolutions

2 - Know the video compression used. H.264 provides a smaller bitrate with equal video quality. MPEG4 is a bit older but still pretty good, about 2x the bitrate of h.264. MJPEG is older and bigger. MPEG2 is even older and even bigger.

3 - Make sure to note that frame rate reduction is not directly proportional to bitrate reduction. 15fps doesn't produce half the bitrate of 30fps. The difference depends on the compression details. MAKE YOUR MANUFACTURER TELL YOU THE DETAILS. :)

Thanks for asking - and feel free to share and argue about it. We're learning, too.

[John Honovich]

"Where in the market are you possibly finding IP cameras with a video stream bitrate under 2Mbps?!?"

It is very common for standard definition IP cameras that use MPEG-4 streams to be under 2 Mbps.

I think your question assumes 30 fps and megapixel - which is obviously different.

However, lots of real world IP camera deployments are using 4CIF or lower with 10 frames or lower. This is generally under 2Mbps and can be under 1Mbps if it is CIF.

[ckodish]

Dear Gryphon,

You state that the Airship NVR can record up to 32 channels of IP video. You went on to "Assume all video is 4CIF/30, both Analog and IP Cameras." And finally ask us to make the "BIG ASSUMPTION" that "the video stream bitrate is the SAME as the Analog example above (2Mbps)".

... My question is: Where in the market are you possibly finding IP cameras with a video stream bitrate under 2Mbps?!?

The lowest I have seen so far is Cisco's 4Mbps HD IP Camera... and I hear rumors for optimized viewing the bandwidth needs to jump to 6Mbps. Other major manufacturers are up around the 25Mbps rate with simply 20fps.

Follow up question: If I give you the benefit of the doubt with an industry leading 4Mbps video stream bitrate, what is the maximum number of supported IP cameras on a single Airship NVR?

[John Honovich]

Does compression choice for IP cameras impact capacity? For example, MJPEG vs H.264.