BI5 dropping frames on Motion triggers

[kennnnnnnnnnnneth]

When recording continuously with motion trigger recording enabled, I lose 10-60 frames at the beginning and end of the motion event.

I am running the latest stable BI5, with four cameras currently, two amcrest, two unifi, though it seems to happen with any manufacturer/model I try.

I have my rig set to record continuously, with BI handling motion detection just for convenience and ease of locating events (the unifis suck hard at it, & if I'm going to have to use software anyway, I'm going to use it for all of them). They are all recording to an external thunderbolt WD purple. The cams and BI server are all on the same switch and subnet so that they can talk at wirespeed, no bottlenecks.

I have tried changing it so that camera motion events, and even an IR sensor, were the trigger, but I still lost frames. I increased the buffer time, which increased the length of the recording of the motion event, which was somewhat helpful, but I still lost frames at the beginning and end of the event. Even when I export the continuous recording of the 5 minute period in which the motion event took place, which is theoretically a separate file from the motion event itself, the dropped frames persist.

Now that I have completely disabled alerts, things appear to be running smoothly - I can't find any new instances of dropped frames. Since that's the only significant change I made, it would seem to rule out network, hardware, and camera issues. I also briefly considered that I might be hitting the I/O bottleneck for the external drive, but even during peak activity it only seems to be using about 15% of I/O capacity, and I make sure to leave at least 250GB free just in case.

Have I discovered a known limitation in the technology, a BI5 bug, or am I doing something wrong?

 

[sebastiantombs]

How is that external drive connected, USB, NAS or eSATA?

 

[kennnnnnnnnnnneth]

USB 3, 5x5Gbps throughput... the drive enclosure supports 3.2 20x20Gbps but my PC only has 3, either way well more than adequate for four cameras.

I also tried using the internal SSD for New footage today and it still had the issue on the internal SSD. If I turn off the motion alert trigger, so that I have smooth continuous footage, I don't seem to lose any frames during testing, regardless of which drive it is writing to.

I have verified that it doesn't happen every time on any camera, but it does happen sometimes on all cameras of at least three different manufacturers. Deductive reasoning isolates it to some difference between smooth continuous footage and footage that is "interrupted" by triggers, but not sure how or why or how to stop it.

Fortunately it is pretty low priority, since you can kinda get around it with increasing sensitivity, making the motion zones 100% coverage, and a bigger pre-trigger buffer, but that makes motion sensing less useful in higher traffic areas since then it's pretty much recording continuously anyway.

 

[sebastiantombs]

People have reported problems when using external USB drives for video surveillance storage. The requirements are quite different than the design of a USB external drive. The data stream never, ever, stops unless you're recording on motion only. The same is true of NAS arrays.

 

[wittaj]

Yep, I tried it once with a USB 3.0 that the specs all say are more than capable. I tried it with just 2 cameras, so ridiculously below the rated specs of 3.0. Didn't last more than 20 minutes before the program I was using to track transfer speeds starting going all over the place and the camera started acting up.

Once you add motion, it adds to the bandwidth needs as well, especially if you are using VBR.

 

[Flintstone61]

It's a good idea in theory to try and expand storage for a SFF form factor PC, but it sounds like for several reasons it hasn't gained popularity, due to issues.
I don't know exactly what they are, if they're were none or few. I'd be a fan.....

 

[sebastiantombs]

Next up is a screen cap of the camera status page in the console. What hardware acceleration are you using? What is the encoding, frame rate, iframe rate and bit rate of the cameras?

 

[kennnnnnnnnnnneth]

My rig does have an eSATA port, and I could pick up an eSATA enclosure, I will do that at my earliest convenience and see if that makes any difference... I am a network engineer and pretty thoroughly understand why NAS is no bueno but hadn't considered the USB standard's linear limitations. I am down to 3 cameras for the time being as I am replacing my front door cam with a doorbell cam, but I figure 3 should cover it.

They are all running at a max rate of 666667 [15 fps], direct to disc h.264/5, Blue Iris BVR file format. Attached picture is right after a reboot. The driveway cam is pretty much black and motionless right now so i think that's why the frame rate is low...

 

[sebastiantombs]

The key frame rate, iframe, on (Cam3) is far too low for reliable motion detection. The bit rate, frame rate and iframe rate need to be set in the camera, not BI. BI can only receive what the camera sends.