Video Frame Drop By VMS?
I was wondering if there is any analysis or report on the frame dropped by VMS recorder.
Let me know if there is link on this topic
Hi Yves,
There are a few reasons why a VMS may drop frames I can think of:
- Network spikes due to other processes on VMS server (Windows Updates).
- In low bandwidth or network constraints the VMS will drop frames first (camera in focus/single view will try to maintain requested FPS)
- Sometimes VMS architecture could cause long requests/response times from camera, dropping a few frames
- High/maxed CPU especially with high frame rates (30) for multiple cameras.
- What about Anti-virus programs, they're notorious for blocking some VMS processes.
And finally, probably the most common, you can view a camera set at 30fps via browser, but when that camera is added to a VMS where there is usually a FPS default (range between 10-15FPS) it will only accept the max requested and drop the rest.
Tell me about your experience, is your VMS dropping lots of frames? at certain times? only some cameras?
It would also be wise to check whether the IP camera is the bottleneck. During some experiments over here, we thought our VMS was dropping packets when displaying full HD H.264@25 FPS video streams. However, it turned out to be that the IP cameras couldn't cope with encoding the H.264 video streams at the designed frame rate.
Thanks Tiago. Yes, cameras are also a culprit, maybe switches too? Which camera mfg/model is it?
Hi Sarit, we ruled out the switch (a NetGear GS724TP) to be the problem. The problematic cameras are Axis P1347 (firmware 5.40.9.2) and Axis P1346 (firmware 5.40.9.3).
Tiago
If you drop the frame rate of the camera, or drop the bandwidth to a lower quality, does your frame dropping problem go away ?
Also, are both of the cameras mentioned being recorded on the same NVR ? If so, start at the NVR. If not, start at the camera / switch / network.
Hello there,
the cameras are viewed on the same video matrix. They are not being recorded on a NVR. The drop in frame rate occurs both individually (i.e., viewing a single camera) or grouped in a 2 x 2 matrix.
I've done the following test just now with a single camera:
Camera model: Axis P1347
Resolution: 1920x1080
Compression level: 30
Video compression: H.264 (GoV lenght: 32, Variable bitrate)
Then, I varied the maximum frame rate as follows:
Max FPS: 10 --> No frame drop
Max FPS: 15 --> Frames are dropped (FPS fluctuates between 10 - 15)
Max FPS: 20 --> Frames are dropped (FPS fluctuates between 10 - 20)
Max FPS: 25 --> Frames are dropped (FPS fluctuates between 5 - 25)
All cameras are connected to the same switch (NetGear GS724TP). Port speed per camera is setup to 100 Mbps. It is worth mentioning that all cameras are facing a full HD monitor displaying "Timescapes".
I can confirm the 1080P@30FPS behavior of that camera. When I use that setting on the camera...I also use the overlay display in the camera setup to show the bitrate and FPS (see http://www.axis.com/techsup/software/amc/faq/faq10.htm) to see the info from the camera itself.
The drop of data happens quickly when one has motion in the view. A static view tends to stay stable.
Lowering the res to 720P cures the motion induced frame drops.
Hello Mike,
sorry for the late response. Somehow I missed your reply!
Just to be sure, which camera are you talking about: the P1347 or the P1346? Did you also use the video "Timescapes" to observe the camera's (mis)behaviour?
Perhaps it's the camera that can't handle the output? According to Axis, the P1347 can output "5-megapixel resolution at 12 fps and full HDTV 1080p"
This would align up with the test you performed.
I'm almost 100% certain that it's the camera that cannot handle the output.
Regarding your remark, I believe you are mistaken with respect to the max FPS for HDTV 1080 mode. It should handle 30 FPS. Take a look at these specs. 12 FPS is indeed for 5MP mode, but not for HDTV 1080. Where did you get this information from?
Tiago
Yes you're right, I mis-read that data. Do you have multistreaming enabled ? Perhaps that's the cause ? Also, try lowering the image resolution. Do you get better performance ?
Hello again,
multistreaming is not being used. We make our tests with a single client connected to the camera and the client views a single (full HD) stream.
Lowering the resolution helps it! However, I think that it's like escaping from problems. If the camera specs state that it can support 1080@30FPS, I would like that delivered, which is not the case when the camera has to cope with a complex scene. To be more precise with you, the camera starts dropping frames (and video quality deteriorates) from 1:44 onwards in the video "Timescapes".
Try CBR
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