Drop in frame rate when camera is being recorded.
  • I have 4 cameras set up, 3 of which are cheap Tenvis 720p cameras from eBay, all 4 work great although for some reason the Tenvis ones work much better using a Foscam profile than a Tenvis one.

    I have noticed however that as soon as the camera starts being recorded (according to a schedule), 2 of the Tenvis camera frame-rates go from 20fps to 10fps, despite all 3 having exactly the same settings in preferences. When the camera recording schedule ends they go back to being 20fps.

    I have checked over and over, reinstalled them etc but cannot find a reason for this - any possible ideas?
  • Sounds like you have SS adding an overlay or otherwise causing recompressing of the video stream. Unless you avoid adding overlays and set SS to avoid recompression, recording will use up more CPU. If your mac isn't fast enough to compress all four cameras, you're going to drop frames. Best is to avoid recompression if at all possible.
  • Thanks for the reply - there are no overlays or changing of the video stream, and what makes it odd is that it is only happening to two of the 3 Tenvis cameras, all of which have exactly the same settings. The Mac is reasonably fast - 2.7ghz i5 with 8gb ram, and the system monitor shows plenty of spare RAM and processor, in fact as i type this it is recording and the system monitor shows SS using 9.8% or the processor availability with 87.76% being idle system-wide.

    Very odd...
  • That IS very puzzling -- slowing down the cameras' attempted, delivered frame rate can't happen. It has to be a throughput issue in how the Mac is accepting the data stream or subsequent processing. The cameras themselves should not actually be slowing down.

    If network packets are being lost or throttled, that could drop the received frame rate, but you're probably also notice dropouts and green screens.

    Is the frame rate you are reporting from the SS camera info window or from playback of the recorded files?
  • I'm as puzzled as Guy at this point :) Everything he says is correct.

    The setting to look for, to check that SecuritySpy isn't re-encoding the video streams (and therefore using more CPU time while recording) is called "Recompress video data" and you'll find it under Preferences -> Cameras -> Device. If this option is not checked then there should be very little increased CPU while recording, and what you are describing should not be happening. So could you please double-check this setting for the affected cameras?
  • I have checked everything over and over and cannot see the cause, there are no re-encodes going on, and the settings are the same for all cameras (feederCam stays at 20fps, garageCam and hutCam drop to 10fps whilst recording, gardenCam is ok but is a different make)…

    http://i1371.photobucket.com/albums/ag293/karljeffery1/Screen Shot 2017-08-22 at 19.52.14_zps93yy5dxj.png
    http://i1371.photobucket.com/albums/ag293/karljeffery1/Screen Shot 2017-08-22 at 19.52.25_zpsarykjrbe.png
    http://i1371.photobucket.com/albums/ag293/karljeffery1/Screen Shot 2017-08-22 at 19.47.54_zpsuclecnvj.png
    http://i1371.photobucket.com/albums/ag293/karljeffery1/Screen Shot 2017-08-22 at 19.49.01_zps90dydyhr.png
    http://i1371.photobucket.com/albums/ag293/karljeffery1/Screen Shot 2017-08-22 at 19.50.14_zpsjb3appmc.png
    http://i1371.photobucket.com/albums/ag293/karljeffery1/Screen Shot 2017-08-22 at 19.50.23_zpsgf3uikkf.png

    All is great when not recording:
    http://i1371.photobucket.com/albums/ag293/karljeffery1/Screen Shot 2017-08-22 at 20.04.19_zps9pfjpumh.png

    but when it records…
    http://i1371.photobucket.com/albums/ag293/karljeffery1/Screen Shot 2017-08-22 at 20.26.58_zpsiiljeh24.png

    VLC shows the frame-rate as being just under 10fps when playing back.

    Processor and memory usage are both minimal.
    Network is showing minimal usage, but i am able to stream HD movies from the Mac to my Apple TV with no issues so have plenty of bandwidth, plus the frame rate only drops when being recorded regardless of what else I am using the computer for.

    Very odd - its not a massive issue to me but it would be nice to know what is happening!
  • I notice in your screenshots that the lower frame rate corresponds to the cameras being in black-and-white night mode. Are you sure that the lowering of frame rate is related to SecuritySpy's recording, and not simply the cameras offering a lower frame rate when in night mode? What happens when you enable recording in the day time? Or turn off recording at night?
  • I'm an idiot....

    It never occurred to me that it could be the camera dropping the fps when going into night mode, not sure even why it would do that as it only happens with two out of the 3! Still, at least doesn't seem to be an SS problem so thanks for all the replies and sorry for sending you off on a wild goose chase!
  • It takes someone with Ben's experience with a LOT of different cameras to think of that reason for FPS slowdown.
  • Agreed. Ben's experience is invaluable.

    FWIW: If I had to guess, a lower frame rate in a low-light condition might be seen in many cameras - depending on how they deal with exposure, aperture size, IR lights, etc... Generally speaking with any electronic photography / video, the lower the lighting condition, the longer the sensor needs to be exposed "per frame" or "per exposure". If each exposure is longer, you end up with fewer frames per second.
  • Well I hope I did hit upon the correct explanation!

    As @xmx says, many cameras will increase their exposure time in order to compensate for low light levels. This, in turn, will reduce the camera's frame rate.

    However this isn't really desirable: while it gives a superficially better-looking image, and allows camera manufacturers to claim better low-light sensitivity, there will be severe motion blur for any moving object in the frame, which will render any moving object (i.e. the thing you most want to capture) very unclear.

    Many (better) camera manufacturers offer a setting to limit the minimum exposure time, to avoid this problem (a good setting for this is around 1/30 seconds minimum). The shorter the exposure time the more noise in the image at night, but the less motion blur there will be - so there is a tradeoff here.
  • Funnily enough i do see a fair amount of motion blur on those 2 cameras, i guess the manufacturer (Tenvis so are cheap Far-East jobbies) has changed something in them despite having the same model numbers are my other Tenvis camera that is ok.

    Perhaps my have to look at upgrading...
  • And just for the sake of completeness, the noise introduced that @Ben mentioned above when shortening exposure... this noise (visual noise, like static or graininess) in the image will make for a more complex data stream for the codec to compress... so if you have a low data rate set to your video stream, which looks fine after compression at a given exposure/lighting condition, and then you increase the noise in the image because you're trying to get rid of motion blur (from the long exposures), you may end up with a different type of blurriness, which is the result of the codec not having enough data per second to describe the image.

    TLDR: If you increase the noise in a stream, you may need to increase your data rate so all the visual static/grain/noise doesn't become blurry itself when the stream is compressed.
  • I have converted about 1/3 of my cameras to Dhaka Starlights. Every single time I swapped in a new Starlight, I have been astonished at the improved night time clarity. You even have to decider whether night is better with IR or in color. They are that sensitive to light. Cost are more than the cheap cams, but with 10x the light sensitivity and good optics, totally worth their cost. The 25x PTZ and varifocal models are fantastic in both day or night.

    They are decently priced if one gets them via Aliexpress. Empire Technology and BEC have been reliable. Those are actually the same company under two different names. The biggest hurdle is getting Aliexpress and your credit card company liking each other. Calling your CC company with the amount and warning them about the transaction just before clicking the order button has been key.
  • I have had a search and for some reason can't seem to track those cameras down, do you have a link at all please?
  • Thanks, I was looking for 'Dhaka'...
  • oops. Must have been typing too fast.

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