H.264 Alarm Recording
Hi,
for sure this is a possibilty any VMS should be able to do.
But the issue is to select an good ip-camera as well.
Because if VMS is receiving stream in VBR with 5 FPS to save bandwith, and than at time of event it should change to 25FPS with higher bandwidth, the camera must be able to restart it encoder very fast.
I do IP-Camera integration now for 5 years, and there are some Cameras which will switch from one frame to the next, and other which will need about 5 seconds to stop sending low framerate stream and start sendnig high framerate stream.
So this is more a question about the IP-Camera then of the VMS. For sure the VMS must be able to do so, too.
Thomas
Without touching camera settings recording frame rate boosting in real time H264 can be changed from I/Keyframe Interval to Full/whateverset Frame rate.
Take below case for I/Key frame interval is 1 per second with total fps of 25.
I,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,I,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,I
Per 25 frames you will receive one I-frame and remaining p/pb frames. if p/b-frames are recorded then we cannot miss intemediate I-Frames because that will result in distorted recordings.
H264 recording frame rate cannot be changed to a user defined frame rate unless camera has the capability to dynamically change Keyframe Interval without reinitiating the stream or VMS taking new sub/secondary stream of the camera. This may result in recording break although very minor.
Also understand most cameras provide I/Key frame interval setting change , but not all. We have seen many cameras ( I can name them) where we cannot change/set I/Key frame interval.
So if you cannot change I/Key frame interval in the camera, then your VMS provider is right in saying it can record only 1fps(default and uneditable) or full frame rate(25 fps or whatever set).
And even if you can change this setting it can only go from I/Key frame rate to Full/whateverset frame rate
I think they were saying you can't do it and leaving off the end of the sentance ,"... because our system can't do it."
I run into any mfg's that don't have some kind of GOP setting. While most are exposed in the web UI and mostly clear (GOP vs GOV) we've run into a couple where it's a bit different:
1) Vivotek - GOP controlled by web UI but definable in seconds vs number of images
2) Arecont - not available to program in the web UI but available to specify programatically in the HTTP calls from VMS
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