title: Which codecs were used in transcoding of a video using ffmpeg
body: <p>During a transcoding of a video how can I figure out which codecs were used by ffmpeg to decode and transcode the video.</p>
  
  <p>For eg. when I do <code>ffmpeg -i input.mp4 output.avi</code> </p>
  
  <p>How can I know which codecs where used to decode the input file and encode to the output?</p>