667. XP PEN/virtual whiteboard during a lecture -- mirroring an application window on linux

The situation:

We're allowed to teach on campus at the moment, but we're also strongly encouraged to adopt a hybrid model where we stream everything via zoom so that students don't show up if they have flu/cold-like symptoms.

We've spent the past few years killing off ppt and transitioning to whiteboard/chalk-and-talk. The students love it -- the pace is better, and the lectures become more interactive since we can adjust our teaching to the students' learning. Good stuff. But horrible for streaming -- you can't just point a webcam at a whiteboard and expect a good outcome (although if need be, it can be done -- just use a good camera and write large with a dark pen).

I have an XP Pen Artist 13.3 Pro (https://www.parkablogs.com/content/review-xp-pen-artist-133-pro-pen-display ) which is fantastic for drawing. A lot of fun, and a potential solution to the whiteboard quandary.

The Problem:

Both the students in the class room and those following the lecture on zoom need to be able to see what you're doing. And since the pen display is a DISPLAY, you need to have your drawing program open on the pen display, and not on the projector (which is also a display).

The Solution:

1. Open your drawing window (xournal, or xournal++ or openboard or krita) on your pen display ... display. 

2. Then run xwininfo (part of x11-utils) and click on your window. You get a window id, e.g. 36000a

Then run x11vnc:
x11vnc -id 36000a

Note the port number -- likely 5900.

The window is now being shared via vnc. 

3. To see it, use e.g. vinagre, click Connect, set the protocol to vnc and the port to 5900 (and you're presumably connecting to localhost). 

Make sure to enable 'scaling', since many old video projectors have a 4:3 resolution ratio, whereas e.g. the xp pen 13.3 has a 16:9 ratio.

Drag this window to the projector.

4. Share the original window via zoom

Note that I've had issues getting the pen display to map correctly when all three display (laptop, xp pen, and projector) are connected. Turning off the laptop screen solved it.

A script:

I've made a script called mirror.sh which starts the x11vnc with the correct id:

winid=`xwininfo |grep "Window id"|gawk '{print $4}'`
x11vnc -id  $winid

664. Capturing sound when recording/streaming lectures/videos. A few devices.

 I'm interested in capturing sound, either during on-campus lectures, or when recording videos, or when lecturing over zoom.

Here are some of the devices that I own, and what I think:

Logitech C920 webcam with integrated microphone:

The sound is ... fine. Even at a few metres distance, actually.  Nothing like a proper, dedicated microphone, but way beyond e.g. the microphone you'd find in a laptop.

BlueParrot B350-XT bluetootch headset:

It's absolutely bloody awful as a sound source. Absolutely fine for listening to music with, but as a headset for recording sound it stinks. The sound during phone calls is fine, but expectations aren't generally very high. Bloody expensive too.

Logitech G930 wireless gaming headset:

Decent sound, but lacks dynamic range in terms of the microphone. Won't work well during a live lecture since it covers both ears. Great at keeping sound out, so very good as a headset for listening to music.

Samson XPD2 wireless lavalier microphone:

Have ordered, but not yet received. You can use it as a lav mic, but I'm going to experiment with using the Zoom H1n below as the input (via a 2x 3.5 mm cable plus a 3.55 mm female -> XLR converter), so that I can record on the H1n simultaneously as I live-stream. We'll see how it works out.

I also bought what is supposed to be a better Lavalier mic (J-082S 044) and a 3.5 mm/XLR adapter:

Blue Yeti microphone:

This is my default microphone for video conferencing and recording videos. It's a great microphone. Cheaper than the crappy B350-XT above. Has several different pickup patterns. I love it. 

I'm using it together with a boom arm I got off of Amazon ('Neuma Professional Microphone Stand with Pop Protection').

Zom Handy H1n sound recorder:

This is my favoure toy though. It's small, light and have great sound. It's a stereo microphone when use as a sound recorded. You can also hook it up via USB (and have it powered via USB) and use it as a high-quality MONO microphone when recording videos or video conferencing. You can NOT record at the same time as you're using it as a USB microphone. I also got the Zoom APH 1 N/GE Accessories Bundle.

The portability makes it great for a number of uses. You can pass it between lecturers that want to record good-quality sound for lecture videos, and it's easy to take home (the Blue Yeti is a heavy beast).

You can also stick it the podium when giving a lecture and it will capture surprisingly good sound. You can record sound and replace webcam sound in post using e.g. KDENLive. You can attach a lavalier mic and use it to record sound during a live lecture and replace webcam sound in post. And more.

It has a 3.5 mm mic input and a 3.5 mm headphone output. I'm planning on experimenting with recording on the H1n at the same time as I've got the headphone output connected to the Samson (above) so that I can stream the sound to my laptop, and share it via zoo, since wireless technologies can be unstable in a lecture hall with lots of phones with wifi running (anywhere you have students). We'll see how it works out.

----------------
Once the audio is taken care of, I plan on using the following for the visual, and use OBS Studio to tie it all together.

Document camera JOURIST DC80

Webcam Logitech C920

I've also ordered a chromakey set for fancier video production. Will be interesting to see how it turns out.

663. Giving a zoom + on-campus lecture (on linux, win and mac)

Preamble:

The uni admins aren't making it easy for us. 

I can handle doing everything on-campus, giving good, or occasionally very good, lectures using the white board and making it dynamic by actually engaging with the target, the students. I can often get them to share my excitement over the amazing stuff we're discussing (especially MO theory -- it's my favourite topic, and my favourite lecture). 

I can handle doing everything online if necessary, optimising my lectures to work through zoom or, even better, do away with lectures completely and rely on pre-recorded videos that take advantage of the video format, and use them to flip the class. We can then meet up on zoom to discuss the topics.

But what we're being asked to do is to focus on on-campus teaching, while making sure that everything is being streamed live online to avoid students from showing up to class when infectious.

Note that in our lecture halls we don't have computers. We're expected to bring our own, and we use single projectors. We also don't get any help from IT. Nothing is ever recorded here.

This is incredibly primitive and unprofessional compared to how things were done back in Australia.

What I will show here:

A few approaches to making a lecture work OK for both on-campus and online students simultaneously, and easily. The solutions assume that there's no competency, interest or support from IT.

1. The Basic
The easiest approach is to start zoom on your laptop, share a set of slides and stream it. You need to think about audio though, and there are a number of wireless solutions.

We've been told to use bluetooth headsets, but bluetooth has poor audio. Using 2.4 GHz wireless headsets, like my old logitech G930, gives better audio, but then you can't hear the local audience properly. 

My preferred solution is to use a Samson XPD2: 
http://www.samsontech.com/samson/products/wireless-systems/xpd-series/xpd2lav/

It's not a headset -- sound won't come out of it, but you can crank up the sound on your computer (or even use external speakers -- I have a very old HP USB speakers that are just about loud enough for a lecture hall (https://support.hp.com/ca-en/document/c02574017)

You can obviously switch input to webcam/document cam etc., but it's pretty basic.

If you have a document camera you can use this just like a webcam. Or you use e.g. https://gitlab.com/docphees/doccam to manage your document camera, and then use the window as input to zoom through share screen.

2. With a bit of Flair

This is a somewhat technical solution on linux, but I think it's easier on win/mac. What we can do is to set up a virtual webcam. The contents of the virtual webcam will be supplied by obs-studio

We then use obs-studio -- in studio mode no less -- to switch between different types of views.

virtual webcam: If you're on linux you need to install v4l2loopback (either as the dkms in the deb repo, or by a very simple compile), and if you're on linux you need the v4lsink. If you're on win/mac you can simply install the virtual camera plug-in for obs-studio.

On linux you need to create a virtual webcam:
sudo modprobe v4l2loopback video_nr=10 card_label="OBS Video Source" exclusive_caps=1

In obs-studio you then choose Tools/V4L2 Video Output and choose /dev/video10

obs-studio
Once that's up and running, set up at least two scenes in obs-studio, and pick studio mode.

I've set up one scene with a lion and a styracosaurus on a webcam, with the background chromakeyed out* over a molecular simulations video, and another one showing the guardian website, but one could've been the window with your slides, and another could be a document camera.

I've then set up ctrl+shift+alt+5 to switch between them:

You can even have different audio input depending on the scene. Useful if you're using wired microphones and moving between different stations in your lecture hall.

In zoom: now all you need to do is to pick the virtual webcam device as your input in zoom. There is a CPU overhead to using obs-studio, so expect the laptop to keep the fan on throughout the lecture.

*The chromakey background is the blue cover of an Office Depot notebook :)