Using an IP camera in conference calls

Debconf Video Team ,Debian
September 20, 2020

My webcam has broken, something that I have been using a lot during the last few months for some reason.

A friend of mine suggested that I use the mic and camera on my mobile phone instead.  There is a simple app ‘droidcam’ that makes the phone behave as a simple webcam, it also has a client application to run on your PC to capture the web-stream and present it as a video device.  All well and good but I would like to keep propitiatory software off my PCs (I have a hard enough time accepting it on a phone but I have to draw a line somewhere).

I decided that there had to be a simple way to ingest that stream and present it as a local video device on a Linux box.  It turns out that it is a lot simpler than I thought it would be.  I had it working within 10 minutes!

Packages needed:  ffmpeg, v4l2loopback-utils

sudo apt-get install ffmpeg v4l2loopback-utils

Start the loop-back device:

sudo modprobe v4l2loopback

Ingest video and present on loop-back device:

ffmpeg -re -i <URL_VideoStream> -vcodec rawvideo -pix_fmt yuv420p -f v4l2 /dev/video0


Read input at native frame rate. Mainly used to simulate a grab
device, or live input stream (e.g. when reading from a file). Should
not be used with actual grab devices or live input streams (where it
can cause packet loss). By default ffmpeg attempts to read the
input(s) as fast as possible. This option will slow down the reading
of the input(s) to the native frame rate of the input(s). It is
useful for real-time output (e.g. live streaming).
 -i <source>
In this case my phone running droidcam
-vcodec rawvideo
Select the output video codec to raw video (as expected for /dev/video#)
-pix_fmt yuv420p
Set pixel format.  in this example tell ffmpeg that the video will
be yuv colour space at 420p resolution
-f v4l2 /dev/video0
Force the output to be in video for Linux 2 (v4l2) format bound to
device /dev/video0