ACTI 7411 MJPEG stream problem

[musher 0]

Hi,

 

Been lurking here a bit and thought I'd throw out a question. I've sent this up to ACTI as a customer support question, but I figured it doesn't hurt to ask here as well.

 

I've got an ACM-7411 delivering an MJPEG stream set to 100% quality. Right now the camera is set up in a garage for testing.

 

When the camera experiences large, rapid light shifts (Like the garage door opens), or drops rapidly to low light, I've been seeing large artifacts (for want of another word) where there appears to be no data. I also am seeing intermittent "framing" problems where the image looks like a 3 or 4 piece puzzle that's put together incorrectly.

 

In relatively constant or slowly changing light, I don't see these problems.

 

I see this in both the acti provided web interface direct to the camera and in video captured by the nvr (blue iris).

 

I've messed around with various settings, but haven't hit on settings that cure this.

 

If anyone has any advice, I'd gladly listen.

 

Thanks.

 

I've attached a couple of photos that demonstrate my problem.

[amirm 0]

What is the speed of the link to the camera? It is possible that it is overflowing its buffer and dropping packets as a result. When you set the quality to 100, you are telling the encoder to not quantize (reduce the fidelity) at all. This can cause pretty massive peaks in data depending on scene content.

 

Try setting the quality to 90 to 95% and see if the problem goes away.

[musher 0]

Thanks for the suggestion,

 

I did mess with the quality setting (down to 50%) while troubleshooting this, but it didn't seem to have any effect on the issue.

 

The camera's plugged into a gigabit switch so any bandwidth limitation would have to be on the camera side. Acti specs show a 10/100 nic on the camera side which matches the status light for that link on my switch (100mb)

 

I've also tried eliminating the switch entirely, just hooking it up directly to a gigabit nic in a laptop. Same symptoms.

 

What I've noticed is that the problem seems worst when light levels go from black (or very low light)->bright (color)->low light(bw).

 

If you look at the framing error sample you can see the garage door is 1/2 closed. This is typical of the scenario that generates the problem:

1. Lights are off (camera in darkness)

 

2. garage door opens exposing exterior lights and headlights shifting camera from low light black and white to color.

3. Car lights go off and garage door begins to close leaving only a 20W bulb for illumination. In the shift back to black and white, I see lots of artifacts and framing errors.

 

If I black out the scene, then bring the light back up, most of the time the errors disappear. If I leave the scene at the low light level, the errors persist for some time (10-15 min).

[amirm 0]

Then it is a bug .

 

Does it do it with MPEG-4 or is it just MJPEG? If it doesn't, does it let you reduce the resolution you are capturing with MJPEG? If so, try lowering it and see if it helps (for debugging reasons).

[musher 0]

Good questions. Too much light out right now to replicate the problem. I'll have to try dropping the mjpeg resolution/changing codec to see if I can isolate the problem.

[hardwired 0]

Try raising the bitrate. I'm wondering, if you have it set for a fixed framerate, with a fixed bitrate too low to support a full resolution image at that rate, that might create some type of corruption during a high bandwidth image change.

 

Also, try updating the firmware, and make sure the correct profile pack for the imager is loaded.

[musher 0]

Hi Hardwired,

 

I'm not sure I understand your suggestion. In the acti interface I only see a "quality" setting for the mjpeg stream.

 

When I switch to mpeg4, there are options for setting max bitrate.

 

Profile is the latest. Looks like there might be a newer firmware. I'm a little reluctant to flash it unless I have to. I'm at 3.12.13. Release notes for 3.12.15 don't seem to address my problem.

 

EDITED TO ADD

 

Ok I found this in the server report, looks like bitrate_current is set to the max--where ever one sets it.

 

VIDEO_RESOLUTION_CURRENT = N1280x1024

VIDEO_FPS_CURRENT= MODE1,8

VIDEO_BITRATE_CURRENT= 3M

STREAMING_METHOD_CURRENT = 0

ENCODER_CURRENT = MJPEG

PROTOCOL = V2.0

STREAMING MODE = Single Stream

[musher 0]

New Data:

 

The camera doesn't immediately appear to have problems with mpeg4.

 

Testing mjpeg at 1280x720 still shows issues. It appears that the output isn't jumbling one frame but combining pieces of two different frames.

 

On the up side, it didn't hurt to get cut in half at the waist.

 

Am I right in thinking this isn't normal for a MJPEG stream?

 

 

 

Guess I'll test at 640x480 next, unless someone has suggestions.

Still waiting to hear from Acti.

[thewireguys 3]

Have you tried upgrading the firmware and profile?

[amirm 0]

Am I right in thinking this isn't normal for a MJPEG stream?

Most definitely a bug. If you were losing entire frames, we could think of other things but not corrupt frames.

 

One final thing though. What is between your PC and the camera? If there is any other device (router, switch, etc), eliminate it and go direct. It is possible that the in-between device is corrupting things.

[musher 0]

The profile is the latest version according to Acti's web site. I guess I better suck it up and flash the firmware. That step always makes me nervous about bricking the device, so I've been holding off in hopes I've done something stupid in the configuration.

 

I have tried connecting directly to the camera & see the same results. No difference with 2 different switches in the circuit either. Only variable there I haven't eliminated is the cat6 cable to the camera. Guess I'll swap that out just to be sure, but it seems to me that this has to be happening inside the camera. What are the odds that all the data between two frames would drop and leave 2 pieces to fit so nicely together?

 

I take it nobody's been seeing this in the Acti cameras on a regular basis?

[thewireguys 3]

Have you tried 2 different computers?

[musher 0]

2 computers?

 

Yep 1 dell laptop and 1 dell server

 

Both are running win 7 x64 though. There's a thought.