About online courses

Covid-19 pandemic and lockdowns usually mean online courses for students... without any cheap solution for addressing a typical problem : a student ask you something during the course and your answer could be sighly simplified with handwritten explanations on the board.

I present here a way to manage an online course with Q&A sessions with such difficulty... and this solution is based on free softwares !

For this, you will need :

A computer with Windows / Linux system
A smartphone with Android / iOS system
A stable Wi-Fi connection (Warning : mobile connection like 4G is not handled)

Warning : the procedure that is presented below is based on DroidCam which does not work with computers equipped with MacOS. However, if you find another software that can replace DroidCam on MacOS, the procedure may be adapted.

Note for students : this is not only for the teachers. You can also use it to prepare your questions and improve your interactions during the courses !

Step 1 (installation) : Preparing the smartphone

The goal is to use the smartphone as a webcam that will be pointed towards a paper sheet that will be used as a board for handwritten answers you will give to the students.

This feature can be reached by using DroidCam Wireless app (available for free on the AppStore and the PlayStore). Install the app, be sure that the smartphone is connected to the Wi-Fi network and run DroidCam. If everything is ok, you should see DroidCam that catched the local Wi-Fi parameters (see Fig. 1).

Fig. 1 (DroidCam in smartphone)

Fig. 2 (DroidCam in computer)

Step 2 (installation) : Preparing the computer (only for Windows or Linux systems)

You will first need the DroidCam client associated to your operating system. Download and install the client by following the Install Notes (see here for Windows and there for Linux).

On another hand, you have to install a video player like VLC Media Player and your favorite video-conference client (see Step 5 below). Be sure that the video-conference client allows screen sharing.

Step 3 : Connecting the computer and the smartphone

Be sure that both computer and smartphone are connected to the same Wi-Fi network, then run the DroidCam client (computer) and be sure that the app is also running (smartphone).

You have now to configure the client (computer). For this, you have to select "Wi-Fi / LAN connection" and provide the local IP address and the DroidCam Port as it appears on the app interface (see Figs. 1-2).
You can also activate several options such as the smartphone microphone, the zooming feature of the camera etc. Personally, I do not activate the smartphone microphone since it induces awful audio feedbacks.

Once you finished your configuration, click on "Connect" and, from now, do not close the client nor the app (see Steps 4-5 below).

Step 4 : Importing the video signal from the smartphone to the computer

I recommend here to use VLC Media Player but you can also use your favorite video player if it can handle video acquisition from an external device.
If you are using VLC, run the player and select in the menu "Media" > "Open Capture Device" (Fig. 3). In the following window, select the Video Device Name then click on the "Play" button (Fig. 4). If your have run the DroidCam client from a terminal, you may find in this terminal some information for choosing the good device (Fig. 5). In my case, it is /dev/video2. If your configuration is good, you should see in your player what is got by the smartphone camera (see Figs. 6-7). Leave it running as long as you will need it (see Step 5 below).

Very important : since the video signal is redirected through the Wi-Fi network, be sure that the connection is stable on both devices otherwise you get a laggy rendering.

Step 5 : Use it during a video-conference

Open your video-conference client (computer) and start the conversation/course/whatever. Each time you need to write something on a paper for explaining something, you have to activate the screen sharing feature of your video-conference client, then select the video player (VLC) that runs with the input signal from the smartphone (see the example with Zoom in Figs. 8-9-10).

Step 6 : How to close everything safely after the video-conference

It is recommended to close the software and apps in the following way:

Close the video-conference client (computer),
Close the media player (computer) that receive the video signal from the smartphone camera,
Stop the connection in the DroidCam client (computer), then close it,
Close the DroidCam app (smartphone).

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