Subscriber Discussion

How Consistent Are DVRs For Recording Low Frame Rates?

BW
Barbara Worsham
Apr 05, 2017
IPVMU Certified

 I have heard that if a DVR is set to record a low frame rate, such as 1 frame per second, the DVR could be recording that frame from anywhere in the 1 second block of time. Is the spot that the DVR records the frame in that 1 second block of time consistent of does the spot vary? 

For example, if a second is divided into 30 units, does the DVR record the frame at unit 1 out of 30 each second or does the DVR record at unit 1 out of 30 in 1 second, unit 5 out of 30 another second, unit 29 out of 30 another second?

Is the DVR consistent - recording at the same unit in the 1 second block or time or is the DVR inconsistent - recording at different units in the 1 second block of time? 

Does the DVR recording consistency vary from manufacturer to manufacturer?

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Ethan Ace
Apr 05, 2017

I have not tested this to be sure, but anecdotally I would say that it varies a little bit. I wouldn't expect it to be so consistent that it hit at the same millisecond mark within each second every time, but it should be close. 

If it's not close, the capture could eventually "slip" to the point where it "skips" a second and no video is captured. That would be the worst case scenario. But I have not personally seen that happen.

Maybe others have input on their experiences here.

 

BW
Barbara Worsham
Apr 05, 2017
IPVMU Certified

thank you, Ethan.  I would like to hear if anyone has tested or have had to deal with DVR precision.

JH
John Honovich
Apr 05, 2017
IPVM

With hard drives so large / relatively inexpensive and codecs continuing to improve, why only record at 1fps? I know this does not answer your question but if one is really concerned about this issue, there is a straightforward and usually simple solution, just increase the fps to 2, 3, or 4.

BW
Barbara Worsham
Apr 05, 2017
IPVMU Certified

I analyze video and have to work with what they send me.

I have no control over the record setting.  Many videos I receive are recorded at 1 fps. 

I am happy when I receive a video that is recorded at a higher frame rate.

JH
John Honovich
Apr 05, 2017
IPVM

I understand. That makes sense. This issue does not come up so often so I do not know. Are there timestamps on each frame that could help show exact time differential?

BW
Barbara Worsham
Apr 05, 2017
IPVMU Certified

The majority of the timestamps are rounded to the nearest second and do not show frames.  I also get many of videos with no timestamp at all.  I have seen more detailed timestamp when I export single frames.  That is something to check when that is available.

 

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