How to install Open Broadcasting Software OBS on Trisquel 8

If you attempt to install OBS using the Ubuntu installation directions provided at the official OBS website you will likely encounter a problem with unmet dependencies as the software requires libfdk-aac0.

ie "Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
obs-studio : Depends: libfdk-aac0 (>= 0.1.1) but it is not installable
E: Unable to correct problems, you have held broken packages."

This package is not included in Trisquel due to patent issues. A patent license is required for all manufacturers or developers of AAC codecs. For this reason, free software implementations such as FFmpeg and FAAC may be distributed in source form only, in order to avoid patent infringement.

Fortunately it's not really necessary to install this. However the developers don't currently make it easy to avoid.

We have gone and installed OBS on Trisquel 8 and successfully tested the following "simple" if not totally ideal work around:

Step 1: Open a terminal

Step 2: Run the below commands

sudo add-apt-repository ppa:obsproject/obs-studio

sudo apt update

sudo apt install libavcodec-ffmpeg56 libavdevice-ffmpeg56 libavformat-ffmpeg56 libavutil-ffmpeg54 libc6 libcurl3 libdbus-1-3 libfontconfig1 libfreetype6 libgcc1 libjack0 libluajit-5.1-2 libpulse0 libpython3.5 libqt5core5a libqt5gui5 libqt5gui5 libqt5widgets5 libqt5x11extras5 libspeexdsp1 libstdc++6 libswresample-ffmpeg1 libswscale-ffmpeg3 libudev1 libv4l-0 libx11-6 libx11-xcb1 libx264-148 libxcb-shm0 libxcb-xfixes0 libxcb-xinerama0 libxcb1 libxcomposite1 libxfixes3 zlib1g

apt download obs-studio

ar x obs-studio_22.0.2-0obsproject1~xenial_amd64.deb

tar -xzf control.tar.gz

sed -e s/"libfdk-aac0 (>= 0.1.1), "//g -i control

tar -cvzf control.tar.gz control

ar rcs newpackage.deb debian-binary control.tar.gz data.tar.xz

sudo dpkg -i newpackage.deb

Source: chaosmonk