imagine an app that is sort of like a panic button. You get pulled over, you open the app and hit the button which then (depending on your preferences), starts recording/streaming video and audio, locks the phone, and maybe starts recording accelerometer/gps data, etc.

It would need to be thoroughly developed/tested before actually it could be ethically recommended.

What do you think? Good idea? Bad idea? unfeasible? Already existing?

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[–] solrize@lemmy.world 4 points 3 days ago (3 children)

Dash cams do this continuously I thought. Good? Bad? IDK.

[–] cvieira@lemmy.ml 6 points 2 days ago* (last edited 2 days ago) (1 children)

This is a bit of self promotion, but I built an entirely open-source dash-cam that excels in this scenario. Instead of recording to an SD card inside the camera, the camera is connected to a capture device installed somewhere else in the car.

It's not perfect, but it's very time consuming for a potential adversary to locate the video storage. It was designed like this primarily for car break-ins, but it would work well here as well.

It all runs on a generic Linux SBC, so there's technically nothing stopping you from encrypting the SD card too.

[–] solrize@lemmy.world 2 points 2 days ago (1 children)

That's pretty cool! Any hardware info? I had thought a diy dashcam project would be most about hardware (rpi zero and 3d printed enclosure maybe) with the software being relatively simple. Using an old phone might be another approach.

[–] cvieira@lemmy.ml 3 points 1 day ago (1 children)

I will say it's quite a bit more expensive than a typical off-the-shelf consumer dash-cam, since you're essentially just installing a full-blowm compurer. I use a Raspberry Pi 5 for the pre-made kits, which is able to record 30fps@720p across two channels (front/rear). It'll work with just about any USB webcam. The tricky part for new users is that you typically have to create a 12V to 5V USB harness to power it from the car.

[–] solrize@lemmy.world 1 points 1 day ago (1 children)

Cig lighter phone charger won't supply the 5v? I'd have thought the camera mount and enclosure would take the most effort. Raspberry pi zero with their camera accessory would be the main camera.

[–] cvieira@lemmy.ml 1 points 17 hours ago

It might, but the Pi 5 has pretty strict power requirements. The official specs reccomend 5V5A, while most 12V adapaters supply 5V2.4A (or 5V1A for the cheap ones). It'll generally work, but customers often experience strange behavior with questionable power supplies.

Mounting the camera isn't terribly difficult. A significant portion of USB cameras have 1/4th inch tripod mounts, which gives you a lot of options. I personally use a little adhesive GoPro mount, with a small 1/4th inch tripod adapter. That lets you securely mount it just about anywhere with a flat surface. The camera's cable is several meters long, which means you can mount the Pi just about anywhere. In my install you have to disassemble a significant portion of the car to get to the SD card (video is typically offloaded over LAN, which is password protected).

I will say that the Pi Zero is almost certainly insufficient for video recording. In my tests, the Pi 5 tops out at about 2 channels of 720p@30fps, while the Pi 4 struggles to encode one 480p@30fps stream. I've been researching SBCs better suited to video encoding, like the Nvidia Jetson, but I'm not quite ready to invest in dev kits for a non-profit project when other components of the software are much more commercially successful.

[–] floofloof@lemmy.ca 5 points 3 days ago (1 children)

You need something that streams to a secure server, so the police can't just delete the video.

[–] solrize@lemmy.world 4 points 3 days ago* (last edited 3 days ago)

Do the police take your dash cam if they pull you over? Does that show on their own badge cam?

Streaming live video takes a lot of bandwidth and connectivity from a car can be intermittent, but maybe it's enough to send a timestamped hash every few seconds, so there is tamper evidence in case of a deletion.

Anyway, deleting video through a dashcam user interface is like deleting a file on a computer: basically a little bit of metadata is overwritten but the underlying data can usually be mostly recovered with filesystem repair or forensic tools. To really delete it for sure you have to either destroy the media or use special tools to overwrite the data blocks. Or just running the camera for a long time (to make sure the freed blocks get re-used) might do it.

You could also stream to another phone or computer tucked away elsewhere in the car, unless you expect the whole car to be seized.

[–] echutaaa@sh.itjust.works 4 points 3 days ago

Dash cams are a bad option, cops have and will delete footage that doesn’t fit their narrative in court.