Default with dashcams you get a PSU that plug into the dash 12 V socket, and this is just fine if you route the wire fine and just want to record while driving. problem is some times that 12 V are live all the time, so then you would need to go for a fuse in the fuse box that is ACC and shut down when you turn off the car. ( i have on rare occasions heard that the dealer can reprogram the dash socket to not be on all the time )
Most hard wire kits today ( for parking guard ) are 3 wire kits that have two +12 V wires needing connection, one to a always on fuse, and one to a +12 V ACC fuse, and then of course the ground wire.
Some systems can still use the old way where it is the camera G sensor that determine if the camera should be in drive mode or change to parking guard mode ( usually after a few minutes of 0 movement on the G - sensor.
These old style cameras just need 2 wires in the hard wire kit.
You can have the G sensor on while driving, then it would save a event file in a locked folder for safe storage, but really with a sufficient large memory card you have storage enough for 10 - +20 hours of recording, so you would have to crash down a cliff side, never be found or found many days later, and the car after stopping down the cliff will have to be on for the camera to continue recording and eventually overwrite the crash files too.
I never use the G sensor when driving, first of all if you can not get the sensitivity low enough potholes and similar little bumps can set off false event recordings taking up space on your memory card.
I do use the manual event button to save little things in traffic i want to share, mind you both that button and the G - sensor triggering, what i saved can vary in between brands.
Some systems have a 10 - 20 second memory pre-buffer so you get that time from before the actual event / button press saved, and then 20 . 30 seconds after the event trigger, the downside here is you have to be fast pressing the manual event button to lock the event itself within the 20 second buffer, as for when the G sensor trigger you have the 20 seconds from before the trigger.
Other deal in the video segments them self ( i always use 3 minute segment size if i can ) so the camera might lock the current file being written so you could get how many minutes of segment you have selected.
The downside here is if you are using 3 minute like me and you press the button right at the event happening, and that by chance are right at the start of a new 3 minute segment, well then you could have next to nothing before the trigger saved + about 3 minutes after,,,,, similar problem if you press button / have event right at the end of the current 3 minute file being made, in that case you might have about 3 minutes from before the event and very little after locked down.
Street guardian ( not cheap brand ) they do segments but 2 from each camera, so again me using 3 minute segments, say i have a event 2 minutes into the current recording, well then the SG camera save that current file ( 3 minutes ) + the following file as the trigger is more than 50 % thru the current file when the trigger happen.
So in that case you have 2 minutes from before the trigger and 4 minutes after,,,,,, on the other hand being only 1 min into current file when trigger, still current file get locked, but so do previous as current file was less then 50% when trigger happen.
And so in that example you get 4 minutes from before the event and 2 minutes after the trigger event.
And so with the SG way of doing things you dont have to rush to the event button, and you should still have the actual event locked.
wifi as just about standard these days, and it is good for making settings changes on a larger phone screen, downloading data in bulk, thats not going to work due to slow wifi, but you can spend 4-5 minutes downloading the last 3 minute file your camera saved.
Personally i use a USB 3.0 card reader on a just as fast port in the computer, and i get the full read write speeds of the memory card, which are often up around 100 MB/s VS on wifi where you get much slower speeds.
I would never share event footage on site , not even if it was a event i was not involved in, but i will share later on, as i have done a few times now with police and unfortunate drivers.
Very few dashcams have station mode, so they could connect to your home wifi, but the wifi radio in the dashcam are still very slow and weak ( and inside a metal box so range are probably very limited )
Some of the more smart cameras can connect to a wifi AP in the car or put in the car, these are the more expensive cameras from Blackvue and thinkware.
I have never been impressed of these smart cameras as we geeks have nicknamed them, its just more things that can go wrong.
I am however getting one such system to test in January some time, so while not a fan, this old dog can still learn new tricks,,,,,, just not sure it is tricks i will do for the rest of my life, but i am openminded and will give it a spin at least once.
Driver of this car ( not the first one out of the car ) he did a runner as he was high as a kite, but not before posing in front of my side camera ( not in YT video )
So police was very happy when they saw the footage 1 hour later, cuz !!!!! thats "Jamil" he is a usual suspect, we go pick him up and get drug screen.