recorded file sizes

jamesconnolly

I have a two cameras setup. Front and back camera. Both cameras are setup the same, H.265, 2560X1440 fps 15. On SecuritySpy they both show as 15fps 3.7M per frame. However I notice that over a 24 hour period the front camera file is around 19GB and the back camera around 27GB. Why is there a difference ?

Both cameras are Geovison and record onto a mac mini m1.

Thanks James

jamesconnolly

Something to do with p-frames maybe ? i.e. there is more changes per frame on the back camera, more activity ?

Ben

There are a few factors that can influence camera data rate, primarily when using VBR (Variable Bit Rate) encoding rather than CBR (Constant Bit Rate) encoding:

- The general complexity of the image: an image of a blank wall requires far less data to encode than an image of a complex scene with lots of objects and detail. This can add up to a significant amount over the course of a day.

- Amount of activity: the more activity that happens in front of the camera, the higher the bit rate.

- Exposure/aperture settings in the camera - this affects how much noise is in the image, especially in low light, can and therefore influence the data rate.

- Lighting at night: the better the lighting, the lower the noise in the camera's image and the lower the data rate.

- P-frame interval - the longer the interval the lower the data rate (but this doesn't affect the data rate too much if more than about 3x the frame rate).

You can compare the data rates of the two cameras in SecuritySpy's Dashboard feature. If there is a bigger difference at night, this points to a lighting/exposure factor.

Finally, we always do recommend VBR encoding, with a high quality setting. This allows the camera to use the optimum data rate for the current conditions.

jamesconnolly

Thanks for the explanation, I have VBR setup and it's running at the default 50% quality which is 3072 bit rate, it says the possible range is (128-16384). My images are 2560X1440 fps 15. I might up the quality % a bit. Also, the I frame interval is 50, I'll drop that to 25 as recommended in the installation guide.

The software has been excellent so far, way better than my previous windows based system. can't believe the speed when looking back at captured files.

Thanks James