Good question, and not that easy to explain as the two terms are often (wrongly) used interchangeably in reference to CCTV. So basically varifocal lens are smaller and cheaper than a true zoom lens. But still allow you to "zoom" in on the area of interest.
The key difference between a varifocal and a zoom lens can be explained by thinking about a lens that has been focused on an object at any focal length. A varifocal will need to be refocused whenever the focal length is adjusted; the zoom will stay in focus when the focal length is adjusted (i.e. when "zooming in" or "zooming out").
While this is an advantage in some applications, if a camera is going to be set-up once at an installation and then stay at the same focal length, the varifocal is a smaller lens that will do the job at a much lower cost than the zoom.
Interesting. Found some pictures that allowed me to understand it a bit. Will add the links, so you can read the entire articles where I got the pictures:
Don't forget that you can take advantage of the 2 video streams that are available from almost all ip cams. Perhaps you can utilize the substream as h264 and use that for live streaming. You can use the h265 stream as a source for recording. From my little tests, i found that there was about 1/3 less bandwidth on the h265 video source compared to when it was set to h264. It might even get better with proper tweaking.
I do have 1 reolink cam, RLC-420-5MP. It was one of my more expensive cams. It is also one of my worst. I can no longer view the video from the cam's ui because it requires flash player. Also, if i connect to it repeatedly, it will crash/freeze. That is one of my cams that i have a start delay so that ffmpeg does not try to re-connect to it for a few minutes to let it cool off. Also, they do not expose the iframe interval / gop setting, and have refused when users have requested it. Most likely, it is designed to work with their nvr system with very little regard to someone who may want to use it with ffmpeg. Unfortunately, the firmware update states that it is not for my hardware model, yet it is for the cam's model. I just put in a support ticket. I will further judge them based on how helpful they are with solving my firmware update discrepancy.
Hey Kevin,
that would indeed have been a great idea: a h265 main straim (with better compression) for recording, and a h264 substream for viewing. Don't know if you have seen Nick's feedback above, but from that I conclude there is no h264 at all...
Same here with my older cams. Horrible...
Thanks for your feedback about ReoLink !!!
They responded very quickly with a direct link to the updated firmware and the instructions to install it. It now contains an html5 video player and uses flv.js to transmux the flv video to mp4 video before feeding it to the media source extension. I am surprised that they just don't use the existing rtsp/mp4 video and send that to the browser to eliminate the unnecessary conversion. And I see that the iframe interval setting is still not exposed for advanced usage. Overall, I am still not recommending the brand.
Morning Kevin,
I really would like to stop my endless comparison, and start ordering some cams.
Because there is always something that is not perfect. So be it ...
Just want to have some decent affordable cams that I can connect to Node-RED...
Back to start. You mentioned some time ago that you were very pleased with your Amcrest camera. Hopefully that is still the case right now?
I found a nice comparison of the Amcress 5MP versus 8MP cameras on youtube. For people interested in these camer's, it is worth to have a look at that video! At time 29:46 there is a nice comparison of both camera's:
The 8MP has a faster processor so it can deliver 30 frames per second (while the 5MP only has 20 frames per second).
The 8MP offers two separate substreams. Not sure if there are many use cases for that?
The 8MP has a bit larger angle of view.
The 8MP has a metal case (where the 5MP has a plastic one?).
But he also says that numbers are nice, but that you should decide based on the images it produces...
So at time 30:44 of the youtube video you can watch the recordings of both cams (8MP on the left and 5MP on the right).
The 5MP cam costs 110 EUR (see amazon.de), while the 8MP cam costs 130 EUR (see amazon.de). Do not quickly see really much other shops that sell them here in Europe. Although it is about 20 EUR extra, I am tempted to go for the 8MP camera...
Do you have any other feedback about these camera's?
I have that amcrest 5mp model. It was at a cost of 55 usd. The 8mp model costs 110 usd. Seeing the price hike they are passing to you in euros, it seems that the 8mp is a better deal.
+1 for having 2 substreams. I would like that feature. For the 5mp model, the main and single sub streams can be independently set to use h265 or h264. This could be good for designing your system for re-streaming and recording, since most browsers cannot play live streamed h265 without conversion. Amcrest uses an asm.js version of ffmpeg to decode the h265 video in the ui, but it struggles. asm.j came before web assembly. (i am currently studying web assembly so that I may be able to make an h265 decoder in the distant future).
Base on the specs, I am tempted to purchase the 8mp right now, but i will have to pass on that for a couple weeks.
I had a quick look last week about h265 video playing in the browser (for the Annke C800 cam), and I indeed saw that the most used option is to use a wasm build of ffmpeg. Which is - like you say - faster than an asm build. Although I assume there won't be any hardware decoding that way...
