title: FFmpeg: how to produce MP4 CENC (Common Encryption) videos
body: <p>What is the correct syntax to do CENC encryption with ffmpeg?</p>
  
  <p>The ffmpeg 3.0 release notes include "Common Encryption (CENC) MP4 encoding and decoding support", and the files libavformat/movenccenc.h and  libavformat/movenccenc.c seem to include everything needed to encrypt MP4 files according to the Common Encryption standard.</p>
  
  <p>However, I can't find any documentation on this topic in the ffmpeg manual pages.</p>
  
  <p>Regards</p>