They should have a filled red circle or red LED showing when recording, as per the convention, plus a filled blue circle or steady blue LED on when they're not, while low battery or another inoperability fault should show a blue half circle or blinking blue light.
When recording is activated, a pure 1-second tone should sound, with an audible voice indicator "bodycam number ### recording" with a timestamp and location. When recording is deactivated, a 1-second series of short chirps , with an audible voice indicator "bodycam number ### deactivating in 30 seconds, 15 seconds, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, off".
That way, if a cop is turning off the camera at an inappropriate time, someone else can start recording before it cuts off, or the cop can cancel the deactivation without interrupting the recording, and if a suspect hears or sees all cops turning off their cameras at once, they might have a possible defense for resisting arrest. Furthermore, the recording of one cop's camera would be able to show if another cop's camera was on or off.
Ultrasonic tones outside the range of human hearing could encode "bodycam ### is recording" or "bodycam ### is not recording" or "bodycam ### case has been opened", so that any available audio recording without a high-frequency filter could decode it enough for a lawyer to request preservation of evidence from that specific camera and then later get the full video.
When recording is activated, a pure 1-second tone should sound, with an audible voice indicator "bodycam number ### recording" with a timestamp and location. When recording is deactivated, a 1-second series of short chirps , with an audible voice indicator "bodycam number ### deactivating in 30 seconds, 15 seconds, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, off".
That way, if a cop is turning off the camera at an inappropriate time, someone else can start recording before it cuts off, or the cop can cancel the deactivation without interrupting the recording, and if a suspect hears or sees all cops turning off their cameras at once, they might have a possible defense for resisting arrest. Furthermore, the recording of one cop's camera would be able to show if another cop's camera was on or off.
Ultrasonic tones outside the range of human hearing could encode "bodycam ### is recording" or "bodycam ### is not recording" or "bodycam ### case has been opened", so that any available audio recording without a high-frequency filter could decode it enough for a lawyer to request preservation of evidence from that specific camera and then later get the full video.