Coding4Fun Drone posts
- Introduction to DJI Tello
- Analyzing Python samples code from the official SDK
- Drone Hello World ! Takeoff and land
- Tips to connect to Drone WiFi in Windows 10
- Reading data from the Drone, Get battery level
- Sample for real time data read, Get Accelerometer data
- How the drone camera video feed works, using FFMPEG to display the feed
- Open the drone camera video feed using OpenCV
- Performance and OpenCV, measuring FPS
- Detect faces using the drone camera
- Detect a banana and land!
- Flip when a face is detected!
No code today. Mostly because I spend a decent amount of time trying to understand how the DJI Trello camera feed works.
In order to access the camera feed remotely we need to perform 2 steps. First we need to send the command “command” to the drone, and then the command “streamon” to enable the video stream. Of course, there is also a command to stop the stream “streamoff“.
In the following sample, I enable the camera feed, then keep the camera feed live for 90 seconds and then disable the camera feed.
OK, once I got this, I needed to spend some time trying to figure out how to get this feed. Based on the SDK details, I realize that the url to access the video feed is:
First I make a try and try to access the UDP feed using VLC, however it didn’t work. So I did a little research, and found that I can use FFmpeg to do this. In case you don’t know about FFmpeg.
FFmpeg is the leading multimedia framework to decode, encode, transcode, mux, demux, stream, filter and play. All builds require at least Windows 7 or Mac OS X 10.10. Nightly git builds are licensed as GPL 3.0, and release build are licensed as GPL 3.0 and LGPL 3.0. LGPL 3.0 release builds can be found using the “All Builds” links.FFmpeg Builds (see references)
I downloaded the latest FFMpeg build, and run the following command locally:
.\ffplay.exe -i udp://192.168.10.1:11111
And after a couple of seconds, I got my drone video feed displayed locally. It has a huge delay from the real action to the camera feed. So, there is some improvement opportunities here.
The video is at 3X speed, and I avoid the initial comments and setup. The main idea was to access the video feed and it’s done. Now, in next posts, I’ll try to use OpenCV to work with the feed and maybe process and display each frame independently.
Important: when you run the ffplay command, it will show an scary output, and we will get a great windows with the camera feed. This is the PowerShell output: