title: ffmpeg install failing on docker container
body: <p>I have a Dockerfile as below, where i am trying to install ffmpeg for audio-video processing.</p>
  
  <pre><code>FROM ubuntu:18.04
  RUN  apt-get update  
  RUN  apt install ffmpeg -y --fix-missing
  </code></pre>
  
  <p>I have tried other versions of Ubuntu docker image as well, but i keep getting the error as </p>
  
  <pre><code>E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/s/slang2/libslang2_2.3.1a-3ubuntu1_amd64.deb  503  Service Unavailable [IP: 91.189.88.162 80]
  E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/l/lm-sensors/libsensors4_3.4.0-4_amd64.deb  503  Service Unavailable [IP: 91.189.88.162 80]
  E: Aborting install.
  </code></pre>
  
  <p>Where if i use the Libav-tools as :</p>
  
  <pre><code>RUN apt-get install libav-tools -y
  </code></pre>
  
  <p>I get the error as I need to update to avconv version 10, which is not helping either.</p>
  
  <p>Can anyone here help for how should I go about extracting audio from videos on docker container ?</p>