Imagine your network between the RPi and Smartphone has a huge packet loss/ RTT delay, this script can reduce the quality of
the video in order to give you the possibility to see the video stream without lag but with lower quality.
Supposing you are running the src/scripts/start_stream_gopro.py already, you
should be able to
receive the packets sent by the GoPro via udp://:8554
Since you are receiving the UDP packets from the Go Pro, its time to Capture them and generate a videostream. To do this you
will need to run this script: src/scripts/start_stream_ffmpeg.py
To run this script you will need to open a new terminal and type this :
python2 start_stream_ffmpeg.py
This script fetches the stream of UDP data using FFmpeg , changes it and sends it to whererever you may need the stream to
be.In this case, I send it to the temporary file feed1.ffm which is reachable on port 8090 of my raspberry. This file was
previously configured onRpi_configs/ffserver_configs
The most important "feature" of this script, is the use of FFmpeg and FFserver to join the UDP packets and captured from
the GO Pro and generating a videostream with them. You can then change the video format, the resolution,etc and you can
also stream a modified version of the video to one or more devices.
Below is a UML Diagram that explains how the script works:
If you want to know more about it check the next section
This function, starts the FFserver in a background state, as it uses nohup . This allows the Python script to run
while the FFserver and FFmpeg are launched. This also means that if for some reason the user logs out of the account
the program will still be running. To stop/kill this process you will need to send a SIGTERM or SIGKILL signal to the process.
The configurations that can be used by this function are located Rpi_configs/ffserver_configs/
This function starts the FFmpeg the same in the same way that FFserver is started.
It receives 3 inputs :
- quality, resolution of the video (ex: 720x480)
- streamin, location of the input stream(ex: udp://:8854)
- streamout, location of the output stream(ex: 127.0.0.1:8090/feed1.ffm)
When running these fucntions nohup process is launched. This means that the Pyhton Script forks a nohup process which will
later fork a ffmpeg process.
This little detail can cause you some headeaches, if you are not sure what is the PID of the process you want to be running in
bakground.
This function is used to kill the processes running in background by their PID. The processes can be FFserver or FFmpeg
processes.