v4l2_webcam

About

This project makes it possible to access a single physical webcam from two or more processes. We introduce nothing new; rather this project is like a how-to.

Requirements

• v4l2loopback

• ffmpeg

Explanation

v4l2loopback creates virtual video devices which can be used as video inputs like a real webcam, but they are not associated with anything by default. To make them useful, you shall send streams to them via external applications. For example,

• By sending a webcam's input to a virtual video device, it can be usable as a "replica" of the webcam.

• By sending OBS's output to a virtual video device with obs-v4l2sink plugin, you can use the output as a webcam.

This project handles the former case though the example in Example applies the both cases.

Usage

$ source v4l2_functions.sh
$ create_video_device 5 6 #This creates `/dev/video5` and `/dev/video6`.
$ send_webcam_to_video_device 5 #This sends a webcam's input to `/dev/video5`.

While a physical webcam can be accessed only from a single process at a time, a single virtual video device can be accessed by multiple processes simultaneously. Thus, as in the example above, /dev/video6 is just a spare device (can be omitted).

Example

Structure

Fig: Example setup (structure).

Result

Fig: Example setup (result).

Tested Environments

OS

• Arch Linux

Clients

• Firefox

• Chromium

• OBS

• Zoom

Q&A

• Q. My webcam has unexpectedly low FPS (e.g. 5 FPS). How can I heighten the fps?

In our case, just plugging off and on a webcam solved the problem.