30fps vs 60fps Shootout

I've been paying attention to some of the 60fps marketing stuff lately. It's been puzzling, because almost nobody records at 30fps today, so why would they want 60?

An interesting test, IMO, would be a 60fps 720p camera against a 8fps 8MP camera, or something similar. Does more lower-res frames offer more value in a real scenario than fewer higher res frames?

It is stange that the 60FPS storage demand is only 50% greater, and not 100% greater?

Does the 60fps rate make a difference with recording at night? Bosch's Flexidome Starlight HD720P60 RD is allegedly super effective at night because of the 60fps frame rate rate. I haven't been able to get one to test yet. Do you have any experience with it?

Would it impact the image quality if MJPEG where used? Or only I-frames in the H.264 encoding?

I'm thinking that the quality of the H.264 encoding can be a factor if there are large parts of an image changing at the same time.

So who has 60 frames now? Bosch, AXIS, Sony, Samsung?

I know that Sony's Gen 6 all can record at 6- fps and the reason the 60 frames is getting some notice is because these can be spread over 3 separate streams.

Hi John,

Another benefit of 60 fps is lower latency. About half compared to 30 fps, useful for PTZ. So even if you don't choose to record at 60 fps, you can stream at 60fps for live view and the lower latency.

I am surprised you got as high as 50% higher bitrate at 60 fps vs 30. I would have expected 30% in the typical case but it depends on the amount and type of motion and the camera used. Also, did you adjust the GOP size from typical 30 to 60 (i.e. one I frame every second)? If not, this could explain the higher bitrate.

True, IBP frames can give you up to another 20% compression compared to just IP when there is much motion. As you found, each additional B frame from IBP to IBBP etc gave some small improvement. It's not until you start using hierarchical B frames and dynamic GOP (as in professional broadcasting H.264) when you can get another notch up in compression level. Haven't seen this is IP suveillance systems yet.

It is surprising that not all VMSes support B frames these days (i.e. they are main and high profile compliant) when there is storage cost to be saved. But I guess some are in the business of selling disk drives...

60 fps is also benficial for B frames since the correlation is higher and since the latency is cut in half, the added frame that B frames add, will be moot. One still can hear from some that B frames is bad because of it adds a frame of latency... In addition there are cameras that can stream one IP stream (for view) and one IBBP (for storage) stream. One frame delay at 60 fps is 16mS.

Regards,

BC

Kyle, that list sounds about right to me. Basler also has a couple of 60 FPS models, but they're VGA. There are probably a few others, but those are the ones that come to mind.

Birger, I haven't tested MJPEG at 60 frames, but in our H.264 vs. MJPEG shootout, we found few appreciable differences between H.264 and MJPEG. The camera we used can also automatically adjust the I-frame interval, so in high-motion scenes it will send more I-frames. There's no way to set it to all I-frames, however (minimum interval is 3).

Hi Ethan,

Nice article!

Wich tool did you use to measure bandwidth and video features in the tests?

Thank you.

Hi Luiz, thanks!

I used a combination of VLC media player and AVInaptic to check bitrate for the clips in the test. VLC was used to view the RTSP stream straight from the cameras, and record it in its raw state to disk. I analyzed those recordings in AVInaptic.

We talk about using both of these in this tutorial.

John G, I didn't see much difference between 30 and 60 FPS as far as motion blur goes. However, changing to 60 FPS moves the maximum shutter speed from 1/30s to 1/60s, so you're letting in less light, and that shows. It's not a giant difference because the 733V is very capable in low light, but it's noticeable. It would likely have to be extremely dark (we're talking two decimals or more) to have much impact, because even under 1lx right now, the 60 FPS image is quite bright.

Bengt, we didn't adjust the GOP size. The Bosch 733V automatically handles I-frame interval, and we found that in our sample clips, it was generally about one I-frame per two seconds, regardless of framerate.

Regarding the IP/IBP/IBBP limitation, we suspect it's because IBP and higher H.264 profiles are less common and less used than baseline. We're starting to see more implementation of main and high profiles, but they're still hardly ubiquitous. And yes, the Bosch camera can stream on IP stream and one IBP/IBBP stream, as you mention.

Bosch and Axis has - do not know for others

Brian: In our experience clients do not like to see <12fps - its a perception thing (i.e. " I paid huge amounts of money and the motion is all jittery yada yada"). In deploying these products sometimes a you have to fulfill aethestic/emotion desires as well as technical benefits.

What applications besides casinos and machine vision are people using 60fps for? The one that comes to mind for me is video from moving vehicle. If you are trying to do something like LPR from a police car while in motion or surveil from a boat that is rocking, the faster frame rate might help because you now have 100% motion, 100% of the time.

We know that the LPR application from a moving vehicle of a moving, or even stationary vehicle is near impossible anyway. But fast rates might help.

Military customers use fast frame rate for all sorts of applications like bomb target scoring.

Point Grey is moving from machine vision into surveillance too. They have some fast frame rate cameras that are extremely high quality.

Hi, I need a an offline copy of the video

thanks in advance