DVR FPS Question 120fps vs 240fps - is it split by channel?

[RichTJ99 0]

Hi,

 

I have been looking at 8 channel cards that have 120fps & 240fps. There seems to be a few different types of resolution but 320x240 & 640x480 seem to be common.

 

Does the resolution make a difference when it comes to FPS? If you see a card that says it does 120FPS, does that mean it does 120FPS at 320x240 & 60FPS at 640x480?

 

If you have a 8 port card at 120fps, is it 120fps/8channels = 15fps per camera or port? If I have 4 cameras only, will it default to 30fps?

 

If I go with a 16 port card at 120fps, does that make it 7.5 fps for 16 cameras?

 

I just want to get the "standard" math together.

 

Does the resolution eat away the FPS?

 

Is the rest of my math correct?

 

Thanks,

Rich

[RVRBOY420007 0]

Specs can be tricky like that. Generally when an 8ch card says it has 120 fps its at the second or even 3rd hi res setting. The rest of you math is right you just need to make sure to read the specs closely some manufactures try to be deceiving by telling you its real time (30 fps per ch) but thats not true when recording at the highest resolution. Usually setting to the highest resolution will cut the fps in half which is fine, 15 fps is great, I have seen liquor store recording at 2-3 fps. I recommend at least 5-7 depending on what you are trying to accomplish.

[CCTVDude 0]

You should also consider Montion Detection and FPS Priority features that most good cards like the Geo have when deciding what frame rate you need.

 

Most of the systems we do are set with motion detection. So on the 8 cam system, if only 4 are active at any point in time, you have 2X FPS to spread around to the other 4.

 

FPS Priority is good to 'guarantee' a certain FPS to the most important cams, and the rest can split whats left over.

Edited January 10, 2006 by Guest

[CCTVDude 0]

My 100th Post!

 

 

Sorry, had to do it. Back to normal programming...

[rory 0]

Every one is different, they can have different methods of recording also, smart motion recording is getting common, if it isnt already. If you have 8 cameras on a 120fps card and set it to smart motion, it will adjust the recording speed to the highest overall speed depending on how many of the connected cameras are picking up motion at the time.

 

Some Stand alones work like this also, the GE for instance. Now when you look at stand alones that claim 480fps, then you need to think again, most if not all will only record at highest fps in low res mode, depends on the DVR, its just a way of marketing and trying to catch up with the PC based DVRs.

 

I use the Geo and with 16 cameras at 480fps it will record at 640x480, i havent tested 720x480, as well using color cameras it will eat up way too much space, 640x480 alone with a decent high quality color image is eating up 287MB for a 5 minute motion recorded file with MPEG4!

 

Basically with any Decent PC DVR, Resolution generally only makes a difference on how much hard disk drive space it will take up. The faster the speed and higher the resolution you record at, the more HDD space you will need, or you get shorter recording lengths. Regardless, PC DVRs "CAN" give you highest resolution in real time recording on all channels.

 

Rory

[Jasper 0]

Rory, are you using the FastMpeg4 codec or Regular MPEG4?

 

Also are you using the highest quality setting of 5?

 

I have 1 Sanyo Dome recording at 7fps and it was averaging 20MB per 2 minute file.

 

40MB per 2 minute file at 10fps.

 

You seem to be getting better compression if your running all cameras at 30fps. How did you manage that? Motion detection recording?

[rory 0]

fastMpeg4.

 

287MB file for 5 minute clip - 30fps.

[Jasper 0]

Must be the perfect focus ability of yours or your scene is simpler.

 

Is that the Sanyo Dome you are quoting as I know each camera is unique is its storage needs?

[rory 0]

yes the sanyo d/n dome.