title: FFMPEG convert from .mov to .webm - "Unable to find suitable output for vp8"
body: <p>I need a transparent video for unity and the only solution I found is with a .webm.</p>
  <p>a couple of moths ago I used this:</p>
  <blockquote>
  <p>ffmpeg -i input.mov -c:v libvpx -minrate 10M -maxrate 10M -b:v 10M -c:a  -vcodec vp8 -pix_fmt yuva420p -metadata:s:v:0 alpha_mode=&quot;1&quot; output.webm</p>
  </blockquote>
  <p>but now it give me this error:</p>
  <blockquote>
  <p>Unable to find suitable output for vp8</p>
  <p>Vp8 invalid argument</p>
  </blockquote>
  <p>I don't know ffmpeg so I can't change the command.
  Are there errors or I miss some codec?</p>