Audio watermark and synchronization tones for recording devices
A recording device, such as a video camera, emits audio watermarks (e.g., audible tones, inaudible tones) and records audio watermarks emitted by other recording devices. The audio watermarks provide information (e.g., data) such as an identifier of the camera and the identity of the operator. Audio watermarks may further include time information such as a timestamp indicating the time that the audio watermark was emitted by the camera. Audio watermarks may be emitted and recorded at intervals while recording an incident. A processing system, such as a digital video and audio processing system, may receive video information and recorded watermarks from multiple recording devices. The processing system may use the audio watermarks recorded by each recording device to determine which recording devices were in the vicinity of an incident. The processing system may also use the audio watermarks to align (e.g., synchronize) the video recorded by the various recording devices. Alignment of recorded video may permit synchronized playback of the recorded video from the various recording devices. Alignment may further identify at what point during an incident a recording device began and terminated recording.
1. A computer system that implements a digital video and audio processing system to identify cameras that recorded video of an event, the computer system comprising one or more computing devices configured to:
receive first video data recorded at the event by a first digital video camera;
receive first audio data recorded at the event from the first digital video camera, the first audio data collected by an audio sensor of the first digital video camera and the first audio data including an audio watermark output by a speaker of the first digital video camera;
receive second video data from a second digital video camera;
receive second audio data from the second digital video camera, the second audio data collected by a second audio sensor of the second digital video camera and including the audio watermark output by the speaker of the first digital video camera; and
process the audio watermark in the first audio data and the audio watermark in the second audio data to identify that the second digital video camera was present at the event.
2. The computer system of claim 1 , wherein the first audio data and the second audio data further include synchronization tones output by the speaker of the first digital video camera and the one or more computing devices are further configured to use the synchronization tones to synchronize the first video data and the second video data.
3. The computer system of claim 2 , wherein the one or more computing devices are further configured to use the synchronization tones to synchronize the first video data and the second video data during playback of the first video data and the second video data.
4. The computer system of claim 1 , wherein the first digital video camera is one of a wearable camera and a vehicle-mounted camera.
5. The computer system of claim 4 , wherein the second digital video camera is a smart phone camera.
6. The computer system of claim 1 , wherein the second digital video camera is not configured to emit a second audio watermark.
7. The computer system of claim 1 , wherein the first audio data includes multiple audio watermarks emitted during a single recording session, each audio watermark of the multiple audio watermarks identifying the first digital video camera.
8. The computer system of claim 1 , wherein the audio watermark is a second audio watermark and the first audio data also includes a first audio watermark emitted by the speaker of the first digital video camera prior to the second audio watermark.
9. The computer system of claim 8 , wherein the first audio watermark is not recorded in the second audio data received from the second digital video camera.
10. The computer system of claim 1 , wherein the first video data is received via an evidence collection dock and the second video data is received from the second digital video camera via a wireless network.
11. The computer system of claim 1 , wherein the audio watermark includes tones representing a first identifier of the first digital video camera, and wherein the first identifier is stored on the first digital video camera.
12. The computer system of claim 11 , wherein the first identifier is a user identifier for a law enforcement officer associated with the first digital video camera.
13. The computer system of claim 1 , wherein the audio watermark includes tones representing a timestamp that indicates a time that the audio watermark was emitted by the speaker of the first digital video camera.
14. The computer system of claim 1 , wherein the audio watermark was output by the speaker of the first digital video camera when the first digital video camera began recording the first video data.
15. The computer system of claim 1 , wherein the one or more computing devices are further configured to:
receive third audio data from a third digital video camera, wherein the third audio data is collected by a third audio sensor of the third digital video camera and the third audio data includes both the audio watermark output by the speaker of the first digital video camera and a second audio watermark output by a second speaker of the third digital video camera; and
process the audio watermark output by the speaker of the first digital video camera in the third audio data to identify that the third digital video camera was present at the event.
16. A computer-implemented method for identifying devices that recorded video of an event, the method performed by a digital video and audio processing system comprising one or more computing devices, the method comprising:
receiving first video data recorded at the event by a first digital video recording device;
receiving first audio data recorded at the event by the first digital video recording device, the first audio data including an audio watermark comprising one or more tones identifying the first digital video recording device;
receiving second video data recorded by a second digital video recording device;
receiving second audio data recorded by the second digital video recording device, the second audio data including the audio watermark comprising the one or more tones identifying the first digital video recording device; and
processing the audio watermark in the first audio data and the audio watermark in the second audio data to identify that the second digital video recording device recorded the second video data at the event.
17. The method of claim 16 , further comprising aligning the first video data and the second video data based on synchronization tones emitted by the first digital video recording device, wherein the synchronization tones are recorded in each of the received first audio data and the received second audio data.
18. The method of claim 16 , wherein the first digital video recording device is one of a wearable camera worn by a law enforcement officer and a vehicle-mounted camera associated with the law enforcement officer.
19. The method of claim 18 , wherein the audio watermark includes one or more tones representing at least one of a timestamp indicating a time that the audio watermark was emitted by the first digital video recording device and a user identifier for the law enforcement officer.
20. The method of claim 18 , wherein the second digital video recording device is not configured to emit audio watermarks.