Can I use an Android phone as webcam for an Ubuntu device?

You can use any Android phone as a webcam for your Ubuntu PC by using DroidCam.

1. First download the DroidCam app on your android device via the Play Store.

2. Next install adb on your Ubuntu PC:

   sudo apt install adb
   

3. Follow the instructions to install the DroidCam Linux client.

4. On your android phone, enable USB debugging (you need to enable developer mode to do this).

5. Find the drivers for your device:

   • This page provides links to most manufacturers websites: http://developer.android.com/tools/extras/oem-usb.html#Drivers.

   • You can also search Google “ADB Drivers for ___”

6. Plug the device back into computer over USB. If you get a dialog asking Allow USB Debugging, you need to tap OK.

7. Open DroidCam and select the USB option. On the phone you may get a dialog asking Allow USB Debugging, you need to tap OK. Sometimes you need to open USB Options from the notification area on the device and pick PTP mode for that to show up.

For more information on how to set up DroidCam, click here.

To use your android phone as a microphone, check out WO Mic.

To install the Linux client see this.

You will also need to download the WO Mic app from the PlayStore.

Theoretically you can use both WO Mic and DroidCam in conjunction to turn your Android device into a webcam with a microphone.

Apparently running OBS Studio (on your PC) can use a Smartphone (or other PC, as long as it has a current browser) as Microphone/Camera input. This requires obs studio with the "Browser Plugin", which is apparently not yet part of the linux packages. One then opens a site like https://obs.ninja/ or https://kevin.c3voc.de/ on the Smartphone, and copies the generated url as "Browser Source" into obs studio on the receiving device.

The solution suggested by azrdev ist pretty neat, because now OBS Studio for Linux does have the "Browser Plugin" and with this solution you can also benefit from all the other nice OBS features. Instead of using a site like obs.ninja, I installed the android app "IP Webcam" on my phone. With the app you can start "broadcasting" your phone's video signal in your wireless network. With your computer and your smartphone in the same wireless network, you just add an browser source in OBS with the IP adress given to you by IP Webcam. And that's it! Got it to work in about three minutes...