Video Meta Data: DJI Drones
Many years ago, I wrote about the EXIF data in pictures taken with Smartphones. Smartphones often record extensive meta data, including GPS and accelerometer data.
So I wondered how much similar data can be found in footage collected with a drone. As an example, I am using a DJI Mini Pro 4 drone. This is a very common and popular drone, and I have footage available.
The drone has the ability to record video as well as still photos. For the still photos, typically saved in JPG format, the data looks like what you expect from a smartphone. It includes camera parameters, date, time, and GPS coordinates (oddly, the height was VERY wrong in my sample if I used the "exists" tools, but inspecting it with a homemade tool, it looks better. Likely just an encoding issue)
Here is the complete EXIF data from a sample image
| Tag | Value |
|---|---|
| exiftags | invalid field offset (Make) |
| exiftags | maker note not supported |
| Camera-Specific Properties | |
| Camera Model | FC8482 |
| Camera Software | 10.08.04.08 |
| Maximum Lens Aperture | f/1.7 |
| Focal Length (35mm Equiv) | 24 mm |
| Image-Specific Properties | |
| Image Orientation | Top, Left-Hand |
| Horizontal Resolution | 72 dpi |
| Vertical Resolution | 72 dpi |
| Image Created | 2024:03:20 11:43:03 |
| Exposure Time | 1/2500 sec |
| F-Number | f/1.7 |
| Exposure Program | Normal Program |
| ISO Speed Rating | 100 |
| Lens Aperture | f/1.7 |
| Exposure Bias | 0 EV |
| Subject Distance | 0.00 m |
| Metering Mode | Average |
| Light Source | Daylight |
| Flash | No Flash |
| Focal Length | 6.72 mm |
| Color Space Information | sRGB |
| Image Width | 4032 |
| Image Height | 2268 |
| Rendering | Normal |
| Exposure Mode | Auto |
| White Balance | Auto |
| Scene Capture Type | Standard |
| Gain Control | None |
| Contrast | Normal |
| Saturation | Normal |
| Sharpness | Normal |
| Latitude | N [redacted] |
| Longitude | W [redcated] |
| Altitude | 4294927.26 m |
| GPS Status | Measurement In Progress |
| Geodetic Survey Data | WGS-84 |
The coordinates are the coordinates of the drone, not the coordinates of the operator. The serial number of the drone is not displayed. Note that the serial number uses an "Unknown" exif tag and is only displayed with the -u option in exiftags
"Unknown Tags"
| Attribute | Value |
|---|---|
| Title | default |
| GPS Info IFD Pointer | 746 |
| Unknown | 972 |
| Unknown | 1100 |
| Unknown | 2 |
| Manufacturer Notes | 890 |
| Supported FlashPix Version | 808464688 |
| Interoperability IFD Pointer | 860 |
| Device Settings | 0 |
| Unknown | 6TVQL[redacted serial number] |
| Unknown | 24 |
| Unknown | DJI FC8482 |
| Unknown | R98 |
| Unknown | 808464688 |
Some of the "Unknown" data may be sensitive, but I have not redacted it so far. Let me know if I should :)
The video data is a bit more complex. DJI saves 3 different files:
- MP4 File: This is the main, full resolution video file
- LRF File: Lower resolution video file
- SRT File: A file with GPS coordinates in "Subtitle" format (more below)
Users sharing a file are most likely going to share the MP4 file. Like the JPEG, some metadata is embedded in the MP4 data stream. It is less verbose than the JPEG data, but it does include the drone's serial number. I did not find GPS data in the MP4 metadata. Just information about the camera and firmware.
The SRT file contains some basic GPS data for each "time slice". In this format, it can easily be overlayed to the video file.
00:00:00,033 --> 00:00:00,066
<font size="28">FrameCnt: 2, DiffTime: 33ms
2024-03-20 12:59:17.852
[iso: 400] [shutter: 1/320.0] [fnum: 1.7] [ev: 2.0] [color_md: default] [focal_len: 36.30] [latitude: 30.xxxxxx] [longitude: -81.xxxxxx] [rel_alt: 6.500 abs_\
alt: -32.309] [ct: 5695] </font>
Again, only the drone's GPS data is saved, not the operator's location. It has been well documented that DJI includes the operator (or better controller) location in the datastream sent to the drone, in part to comply with regulations in some locales [1]. An image file doesn't necessarily give it away.
[1] https://www.wired.com/story/dji-droneid-operator-location-hacker-tool/
---
Johannes B. Ullrich, Ph.D. , Dean of Research, SANS.edu
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