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I’ve got IP cameras that provide two video streams. One at high def and one at 320x176 or something like that. Currently I’ve got both streams defined in ZM, I do motion detection on the low def stream and link the high def stream to get events in high def.

Anyone compared this type of setup to just ignoring the low def stream and doing motion detection on the high def only? I’m tempted to wipe my install and start from scratch in that setup but was hoping someone had already compared the two and has some insights.

Hi BiloxiGeek!

I've read your post a few days ago, so my late answer.

I have exact same config as you expecting lower computer load.
So your question finally encouraged me to test that.
option 1. : 3MP stream, nodect linked to VGA stream modect. Alarms recorded: 3MP h264 camera passthrough, VGA analysis images only.
option 2. : only 3MP stream, modect, VGA monitor disabled. Alarms recorded: 3MP h264 camera passthrough.

Testing application: Monitorix - https://www.monitorix.org/

Tested on two consecutive days, almost same conditions (weather..), first day option 1., second day option 2. The result surprised me on a first look - no visible/notable load difference.
The second deliberation: ZM do so much, that motion detection on low or high resolution is a small part of a load produced.
option 1. - ZM must handle two streams
option 2. - ZM handles only one stream, the part of a load not to handle low res. stream is moved to motion detection on hi res.
So the result is about the same load of a system on either option. The critical (higher load) are nights, as you can see above.
So to offload, one stream option is better - smaller /dev//shm , events folder and SQL database occupation.

The developers could answer correctly, the above are just my observations and a test results.

I've found that the best performance is with Nodect, and external motion detection. There is a downside, however, that you have to setup the external motion detection.

In this case, you'd have the 3MP stream, and then Nodect on it.

snake wrote: ↑Thu May 16, 2019 1:18 pm I've found that the best performance is with Nodect, and external motion detection. There is a downside, however, that you have to setup the external motion detection.

In this case, you'd have the 3MP stream, and then Nodect on it.

Yes that's obvious , but the question was how to deal motion detection with Zoneminder.