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diff --git a/content/weblog/2020-12-20_zoom-trolling/index.md b/content/weblog/2020-12-20_zoom-trolling/index.md new file mode 100644 index 0000000..fd815c6 --- /dev/null +++ b/content/weblog/2020-12-20_zoom-trolling/index.md @@ -0,0 +1,133 @@ ++++ +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 Binary files differnew file mode 100644 index 0000000..cfbb8d4 --- /dev/null +++ b/content/weblog/2020-12-20_zoom-trolling/zoom-trolling.mp4 |