Pietro Battiston

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In this page, I describe the solutions I am using for remote lectures for students under Linux. All of these should be applicable to other OSes too. There might be other solutions I don't know of, but I did experiment a bit of other ones, and I'm happy with what follows.

====== Class #1: 10 students ======

The best solution is **jitsi**: works well (better in Chrome than in Firefox), good quality, powerful interface, allows to record lectures directly to Dropbox, good mobile app (suggested for students but not for lecturer, as it is more limited).

Only caveat: https://meet.jit.si (which requires no subscription) is sometimes overloaded.

Alternative: meet.google.com . The quality is worse, the option to create rooms for lectures requires enterprise/educational accounts, and the browser interface is less reliable, but servers don't suffer from overloading.


====== Class #2: 50 students or more ======

I use **obs** and YouTube live streaming. You need a YouTube account and to create a channel (approval takes 24 hours!). I use 1280x720 both as base resolution and as output resolution (hence, I get a 720p key on YouTube and put it in the obs settings), and typically put in the scene my webcam, my slides and any other window I want to share.

Inside obs, I disable the "Audio desktop" and, in the "Mic/Aux" filters (gearwheel symbol), I put "Noise suppression" to its default value (-30 dB). Also make sure to pick a hardware-accelerated encoding if possible (FFMPEG VAAPI, in my case) inside the "Output" settings.

Remember to disable the YouTube chat if you don't want to use it. While watching the video does not require logging in, chatting does, so I avoid this solution. Solutions like moodle (the e-learning platform many universities use) include a chat for which students are already registered, so I use this.

In order for interaction to work reasonably, remember to pick the "Ultra low latency" before starting. This allows to get down to ~5 seconds, which is manageable for answering questions via chat.

====== General tools ======

===== Recording =====

For recording, I use **obs** (which is able to record and stream at the same time). YouTube does record live streams, but I found it better to have having my video ready on my disk as soon is finish my lecture.

===== Splitting =====

I always split my recorded videos in 20-30 minutes parts. Kdenlive can do this, but if you are not afraid of the terminal, the following is quicker:

''ffmpeg -ss 00:06:05 -t 32:00  -i input_file.flv -c copy "first_part.flv"''

(in this example, I extract from ''input_file.flv'' the 32 minutes that start from minute 6:05.

===== Whiteboard =====

If you don't have a touchscreen pc/notebook but you do have a tablet (and possibly a cheap capacitive pen), you can open https://whiteboardfox.com on both and share the browser window on the computer (on jitsi/google meet/obs).



====== Solutions I tried and discarded ======

Webex (no Linux support, even in browser, with either Chromium or Firefox), Microsoft Teams (no Linux support in the browser, low quality Linux client, which crashes whenever I try to share anything).

Solutions like jitsi and google meet crash the browser all the time with high number of students (e.g. more than 50).

====== Solutions I still did not try ======

I was suggested **BigBlueButton** .