Unknown encoder 'libx265' on Ubuntu 18.04

Question

I'm running the following command on my Ubuntu 20.04 ffmpeg -i input.mp4 -vcodec libx265 -crf 28 -f mp4 output.mp4

I get the statement: Unknown encoder 'libx265'

I installed the encoder with the command sudo apt-get install libx265-dev libnuma-dev but I still get the same message. Do you know what I am doing wrong or how to get ffmpeg to work with this encoder?

Answer 1

I was getting this error on Ubuntu 22.04. For me, a ffmpeg installation within my conda environment was creating the problem. I was running ffmpeg -i input.mp4 -vcodec libx265 -crf 28 output.mp4 from a conda environment that also had ffmpeg installation which I came to know by running whereis ffmpeg. As a reference, I am pasting below the whereis command output

ffmpeg: /usr/bin/ffmpeg /usr/share/ffmpeg /home/chuchu/anaconda3/envs/py382/bin/ffmpeg /usr/share/man/man1/ffmpeg.1.gz

As you can see along with system-wide installations of ffmpeg, I also have a conda installation. Then I tried running ffmpeg -i input.mp4 -vcodec libx265 -crf 28 output.mp4 command after changing to another conda environment which does not contain conda installation of ffmpeg and it worked perfectly!

Answer 2

I solved it by using

sudo apt-get update -qq && sudo apt-get -y install \
  autoconf \
  automake \
  build-essential \
  cmake \
  git-core \
  libass-dev \
  libfreetype6-dev \
  libgnutls28-dev \
  libsdl2-dev \
  libtool \
  libva-dev \
  libvdpau-dev \
  libvorbis-dev \
  libxcb1-dev \
  libxcb-shm0-dev \
  libxcb-xfixes0-dev \
  meson \
  ninja-build \
  pkg-config \
  texinfo \
  wget \
  yasm \
  zlib1g-dev

as posted on the website - https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu

I understand I was missing an update/some package installations must have changed my previous configuration.

Edit: I ended up getting the same error on a different system. I turned out to have multiple installations of ffmpeg in different locations and the one I was using did not have the required builds. I solved this by removing all installations of ffmpeg (using whereis) and then used the build linked by Gyan in the comments.