IP camera - image issues

[Tomislav 0]

Dear All, I would like to get your opinion.

 

I have two cameras that use MJPEG and MPEG4 compression. They are set to record at 1Mbps and 15fps.

Now we are getting to interesting part.

 

Sometimes when the object is moving I get the image that moves and drags other pixels around that object and as a result I get VERY poor image, useless in fact. Other object that are moving slow are ok but faster ones are with the problem. Can this be issue with the CCD chip? Because I tried to change the compression, fps and other things but still the same problem.

[cricket 0]

Could be the CCD/CMOS sensor need more light or time to grab an image. (common issue on low cost cameras)

 

It is also possible that the processor not fast enough to encode MJPEG or MPEG4.

 

Most likely you'll have to get a better camera for the job

[Tomislav 0]

Thanks it is or it was a quite expensive but older CMOS ip camera. This issues happens during the daytime... I will try to replace is with another one to see if it is the camera issue.

[MaxIcon 0]

What's the resolution? 1Mbps is pretty low for high res cams, but should be OK for D1/VGA res. Fast movement is where problems with a low data rate often shows up.

[Tomislav 0]

It is 4 cif on 1 Giga network

[MaxIcon 0]

Hard to say without seeing the images, but if it leaves a trail of pixels behind a moving image, like partial images or ghost images, this is often an encoding issue, where the update frames aren't all getting through after the key frame.

 

For MPEG4, the key frame should be the entire image, then the next frames are just updates to what's changed. If one or more of them get dropped, you lose some of the changes, and the pixels that should have been updated get left behind as they were. It then clears up when the next key frame is sent. To test for this, you'd check if that's the patter - clear image, then ghost images, then another clear image, on a cycle of however many frames the key frame interval is set for. So, a key frame interval of 20 on a 10 fps camera would give a clear image every 2 seconds.

 

For MJPEG, every frame should be an entire image, which gives better quality, but much higher bandwidth. If it happens on MJPEG too, you may have an encoding issue in the camera itself.

[Tomislav 0]

Thanks Max, I am attaching the sample below. Let me know what you think...

[MaxIcon 0]

Yeah, that's pretty ugly! Does it do this on both MJPEG and MPEG4, and does it ever clear up?

 

If it's frame loss, it's pretty major frame loss. I'd guess it's having problems with a failing component/chip, or possibly overheating. A bad cable or connection could be the problem, too - anything that would cause network packet corruption or data loss.

 

You could test for overheating by unplugging it for 20 minutes, then restarting, to see if the problem is better. Likewise, connecting another camera would help isolate between the camera and the rest of the system, and a different cable should be easy enough to check out.

 

Network troubleshooting software like Wireshark would tell you if you're getting corrupted packets. It's complex software, but there are lots of tutorials if you're not familiar with it. You'd set it to show packets from the camera's IP address, and bad or corrupted packets are displayed in red.

[Tomislav 0]

Hi Max, thanks a lot for the valuable info.

 

I reported my problem to our network people and they removed some settings that they had on the switch. I think it has something to do with QOS but didn't get really clear answers.

Also they changed the settings down to CIF, 10 fps and from MPEG4 to MJPEG and now it is ok. By ok I mean the image is there but quality not so much. I will try to put it back to max resolution, 4CIF and back to MPEG4 and I will monitor it until they change network settings, again, without letting me know

 

Thanks for the tip to use wireshark. I used it but only briefly. It takes some time to get the grip on how it works but ones you do it makes your life much easier, especially with the problems like this.