FPS setting

[alpine0000 0]

First off, I just wanted to say that this is my first post. I've been lurking for about 2 months, but never registered/posted anything because I've just been absorbing the wealth of information that this forum has to offer! Thank you all!

 

Here's the deal...

 

I am trying to squeeze a bit more recording retention out of my DVR, and was considering changing my FPS setting. I did a search on the board tonight for FPS and went back about 10 pages, found some good information, but not quite what I wanted to ask. (feel free to either answer my questions or guide me to a previous post if i am beating a dead horse here )

 

My question is simply this:

 

I have read on this site that "most" people cant decipher anything higher than 15-20 FPS, and I currently have mine set on 30 FPS. What do you guys usually set your FPS on most of the time if you dont necessarily need top-notch quality, but also dont want any choppiness in the video? I want it to look smooth as television (which i hear is 28fps, but i might not need that high to achieve good looking video).

 

I'm thinking maybe 22 FPS would help me out a bit with more retention?

 

Here is my current set up that a bought from one of the great resident online retailers here on the site! (the cameras arent the best around, but im hoping to add more soon and add a PTZ too!). For now I just have 4 cameras, but within 6 months I hope to have 8. I record at 4CIF on the 4th best setting out of 5 choices. i have it set to record video only, not audio. The I Frame is set to 100. I have 3 cameras set to record on motion for 5 minutes after the motion is detected, and one camera is set to record 24/7. I use it for home surveillance, as i am out of town more often than not. I like to this of this as more of a hobby though, as I really enjoy setting this stuff up

 

G4-8RTA-D1 DVR w/ 500g HDD

(3x) G4-400HPT High-Res Infrared Color Camera

G4-9CH-10AMP power supply

IntelliPix IPX-520-DN DPS WDR Day/Night Camera w/ 2.8-12mm Manual Iris Varifocal Lens

 

I think that about sums up my details. If i forgot anything that might be useful, let me know!

 

So, hows about it guys, what FPS do you prefer for a nice balance between smooth picture, yet still a decent retention rate? The choices on my DVR that are above 15 are: 30, 22, 20, 18, 16, 15.

[RickA 0]

I have set DVR's from 1 pps to 30 pps depending on what you are trying to capture, in just a movement type of system, watching for movement to or from something, then anywhere from 1 to 15pps is good, if you are watching for slight of hand movement then upwards of 15 to 30pps is needed to capture a screen shot of what happened. So it depends a lot on what you are trying to capture, if it is just to see what changes and not an exact how the change occures then lower the pps. Hope this helps.

[Soundy 1]

Regular NTSC video (TV, DVD, etc.) is just a hair under 30fps (about 29.97, actually - google "drop frame" for more details, if you're really curious). In most cases though, even 15fps will appear to be smooth-flowing video (until you start getting into fast-moving objects). Dropping from 30 to 15 will approximately double your retention and most people wouldn't be able to tell the difference, or if they did notice a difference would have trouble figuring how or why it looks different. I'd even challenge that you would have a hard time telling the difference if you didn't know the setting had been changed

 

Most systems we put in, we actually only run at 1fps, sometimes 2-3 for certain shots. For things like retail and fuel-service coverage, this is typically all that's really necessary.

[Sawbones 0]

Be careful jacking up the frame-rate. As other posters have already pointed out, it decreases your recording time, and there's definitely a point of diminishing returns.

 

I also found that jacking up the frame rate made my DVR (a Dedicated Micros DS2) respond more slowly to commands from the DVR's built-in webserver.

 

As an alternative, if your DVR does motion detection, run a slower frame-rate as a default setting, and increase it when the motion detection gets tripped. That way you're not burning hard drive space on 15FPS of static image.

[Soundy 1]

Be careful jacking up the frame-rate. As other posters have already pointed out, it decreases your recording time, and there's definitely a point of diminishing returns.

 

I also found that jacking up the frame rate made my DVR (a Dedicated Micros DS2) respond more slowly to commands from the DVR's built-in webserver.

 

That's the other issue - the more you record (higher framerates, higher resolutions, more sensitive motion detection), the more it loads your processor, AND your I/O channel. I've seen significant dropped frames on some systems that are underpowered for the amount of data the users are trying to push through.

 

As an alternative, if your DVR does motion detection, run a slower frame-rate as a default setting, and increase it when the motion detection gets tripped. That way you're not burning hard drive space on 15FPS of static image.

 

Or have it record ONLY on motion-detect. Decent systems will pre-buffer a definable number of seconds or frames, and will continue recording a definable amount of time after motion ceases as well, so you don't miss any of the action.

[alpine0000 0]

thanks guys i dropped the setting from 30fps to 22fps, and i also set 3 of my 4 cameras to record on motion only. This should give me a much better retention rate. if after a few weeks of testing i find that i need more retention, ill drop the fps down to about 15 or 18 and see what that does for me!

 

[Scruit 0]

The DVR for my house is set to D1 10fps and this provides all the information I need for any potential burlgary/vandalism type incident. Good detail, enough motion to show where people are and what they are doing and although you lose a little of the sense of fast-moving dynamic action it's a good trade-off.

 

In my car my dashcam is set to CIF 30fps because the level of detail I need is not that great (I can see the car, lines in the road, streaat signs etc) but the action on a dashcam is much more dynamic and fast-paced and the nuances of certain types of motion are vital to tell the story.

 

For example, my dashcam caught a road rage incident where a driver intentionally slammed his door into my fender. At a lower frame rate you might just have see the door in it's starting and ending positions with no real sense of the amount of force used. At full frame video the acceleration of the door was clear and was convincing enough for the prosecutor to file charges and get a guilty plea.

[Sawbones 0]

Yeah... I watched that video on youtube. Kudos to you for putting the screws to that guy.

 

I don't know what that hothead thought he was doing... that kind of thing could get you shot in some places.

[roygbiv 0]

How much extra recording time you get by dropping the framerate

depends greatly on the compression codec used.

 

With mjpeg the relationship is near linear ie halving framerate doubles

recording time but with mpeg4 and especially H.264 halving the framerate

may only increase recording time by 20%.

H.264 codecs are usually dynamic. In other words it will take more

recording space when recording a lot of movement (I mean continuous

recording, not motion only recording). This can have a bigger effect than

changing the framerate.

 

Also worth noting is that 'noise' cannot be compressed so cameras with

good noise reduction will give much smaller files with H.264.

[Soundy 1]

^Good points, rory.

 

Another thought: if the cameras support progressive-scan, you might try using that as well. I've put in some Pelco cameras with this option, and depending on the codec, progressive-scan video can also be compressed a lot more than standard interlaced video.