In short, a dash cam records audio and video and stores it for a period of time. These recordings can be viewed later if there’s an accident or traffic incident. Many of the more advanced dash cams come with GPS, which can be used to determine vehicle speed, and some come with accelerometers which can sense a crash and preserve the footage taken just before the accident. Most have built-in flash storage, and many are expandable. When the storage runs out, the camera just overwrites the existing data.
Beyond the ability to record video and audio, some types of dash cameras offer added functionality. For example, some dash cameras have a parking function that enables the dash cam to turn on automatically and record if your vehicle is bumped. In most cases, this will cause the camera to record anything that happens in front of it while you are away, which can catch evidence of hit-and-run accidents.
Dual-camera units are designed to record all of the front-facing action on the road, just like a normal dash cam, but they also record the interior of the vehicle at the same time. These dash cams are ideal for ride share drivers (Uber, Lyft, etc.). In addition, many parents rely on installing dual-camera dash cams in their children’s vehicles. If the driver happens to look away from the road to fiddle with the radio, apply makeup, or play with their phone, it will be caught on tape.
Another feature that is sometimes found in these same units is GPS mapping. A lot of dash cameras include built-in GPS functionality already, which allows them to embed GPS coordinates into a timestamp on the video, and that is sometimes extended into a memory that can provide you with a history of where your car has been, and when it was there.
Dash cams record onto a micro SD card. When this card is full the camera will automatically loop and record over the oldest 3-minute file. Recordings can be transferred to a computer to be stored permanently. A 16GB micro SD card can store up to two hours’ worth of footage before it overwrites the oldest recordings. This is when the Dash Cam is set at 1080p HD to record at 30 frames per second. A 32GB micro SD card store up to 4 hours of dash cam footage when recording at 720p HD, or full 1080p HD at 30 frames per second.
Dash cams are legal in all states IF USED PROPERLY. There are two main issues when it comes to dash cams. Privacy and safety. If a dash cam is installed on a windshield, it must not obstruct the drivers line of vision. Accessories are also available to mount the dash cam on the actualy dash board which is another option. In regards to privacy, it is illegal in most states to record someone without their consent. However, dash cams fall under surveillance. Unless you are using your dash cam for anything other than recording the road in front of you as you drive, you should not have any issues.