New post: Zoom trolling

Also modified css a bit so that <video> elements wouldn't occupy more
than 90% of the width of the container.

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+title = "A little fun with Zoom"
+date = 2020-12-20T19:49:00Z
++++
+
+Since the beginning of the Orwellian nightmare that befell upon us this year,
+many of us have been forced to not only fundamentally change the way that we go
+about our lives and interact with other people, but also to use platforms for
+video communications that not only are proprietary, but are also of very dubious
+origin and quality. Well, either that, or fail academically (for those still in
+university, like myself), or professionally (for those being forced to use this
+software at work). That, however, doesn't mean that you cannot make use of the
+situation and have a little fun.
+
+<!-- more -->
+
+**_Disclaimer: I am not responsible for any consequences that may result of your
+use of this trick. Use it at your own discretion._**
+
+In trying to find a way to share my screen on Zoom in Wayland, I thought that it
+might not hurt if I had a little fun in one of my "Zoom classes". After all, I
+was forced to install this Chinese spyware in my computer, the least I could do
+is have fun with it. As is known, many programs lack the ability to capture or
+share the screen in Wayland. I am required to share my screen from time on my
+remote classes, so I was thinking of a way I could do just that.
+
+One day, a thought came to my mind. In Linux systems (as in most Unix-like
+systems) everything is a file. Therefore, webcams are also a file
+(`/dev/video*`). So in theory, I should be able to capture my screen with the
+screen capture software I normally use, and somehow redirect it to a "fake"
+webcam, and from there use that fake webcam in any videoconferencing software
+(e.g. Zoom) as I would my normal real webcam.
+
+As it is most of the time, some people had already invented the solution to my
+problem, and the software I was looking for, came in the form a kernel module
+called `v4l2loopback`. This genius piece of software does precisely what I was
+thinking of, it creates a fake webcam in `/dev`. However, it was only the first
+part of the equation, the second part is the software that captures the screen
+itself and redirects it to the fake webcam. It doesn't even have to be your
+screen, it could be any video stream. After finding the solution, I decided to
+kill two birds with one stone, and test it by being a troll in one of my
+classes.
+
+## Some instructions
+
+I use Artix Linux (i.e. Arch Linux sans Systemd), so the instructions that I am
+writing here apply for that distro. However, I am pretty sure you reproduce
+these instructions with small modifications in any other Linux distribution.
+
+First we'll need some packages. The packages that are or might be of use are the
+following:
+
+* v4l2loopback — the kernel module that will create the fake webcam.
+* ffmpeg — (optional/recommended) if you haven't used ffmpeg yet, I recommend
+that you install it even if you aren't going to use it for the purposes of this
+post. It is a utility for working with video and audio. In this case, it will
+allow us to redirect video files into the fake webcam, or, if you are using X,
+capture your screen and redirect it to the cam.
+* wf-recorder — (optional/wayland;wlroots) this is the defacto program for
+screen capture in Wayland compositors that are based of off
+[wlroots](https://github.com/swaywm/wlroots). In my case, I use
+[Sway](https://github.com/swaywm/sway).
+
+So in Artix/Arch you would install them like so:
+
+```
+# pacman -Sy v4l2loopback-dkms ffmpeg wf-recorder
+```
+
+After installation we'll need to rebuild the boot image:
+
+```
+# mkinitcpio -p <your-kernel>
+```
+
+Where `<your-kernel>` is the name of your linux kernel image, e.g. `linux`,
+`linux-lts`, `linux-zen`, etc.
+
+Before using the module we'll, of course, need to reboot. However, I added a
+little line to my `/etc/rc.local` file, so that the fake webcam would be added
+right upon system boot:
+
+```
+modprobe v4l2loopback card_label="Screen share" exclusive_caps=1
+```
+
+If you don't want it to appear after every boot, you can just execute that
+command as root on your terminal any time you need it. The fake webcam will
+disappear after a reboot. You can also remove them yourself, and add different
+loopback devices, for that, consult the documentation of the v4l2loopback
+project.
+
+Now is when the fun can start. For the first example, showing video in the
+webcam, by using ffmpeg:
+
+```
+$ ffmpeg -i <your-video-file> -f v4l2 /dev/video<X>
+```
+
+The fake webcam should be the last video device if you already had your real
+webcam(s) connected. So if you already had `/dev/video0` and `/dev/video1`, then
+the loopback webcam should be `/dev/video2`, unless you specified it to be
+something else when loading the v4l2loopback module.
+
+Second example, show your X11 desktop in your webcam, using ffmpeg:
+
+```
+$ ffmpeg -f x11grab -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -f v4l2 /dev/video<X>
+```
+
+The last example, and the one that applies to my case, showing the desktop of my
+(wlroots-based) Wayland compositor:
+
+```
+$ wf-recorder -o <display-name> -x yuv420p -c rawvideo -m v4l2 -f /dev/video<X>
+```
+
+I also have a script in my dotfiles for easy screen recording (and now also
+sharing) under Sway using bemenu (dmenu for Wayland)
+[here](https://git.yaroslavps.com/configs/swayrice/tree/dotfiles/.local/bin/swayrecord).
+
+## The results
+
+If you followed the instructions up to this point, then: congratulations! Now
+you can do stuff like this:
+
+<video loop muted autoplay>
+<source src="zoom-trolling.mp4">
+</video>
+
+Well, of course, you can be better than me and actually use it for something
+useful, like sharing your presentation slideshow with your peers. But where's
+the fun in that?
diff --git a/content/weblog/2020-12-20_zoom-trolling/zoom-trolling.mp4 b/content/weblog/2020-12-20_zoom-trolling/zoom-trolling.mp4
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