title: Does simple rescaling from 1080p to frame height of 720 lead to 720p?
body: <p>I want to convert a 1080p to 720p and also lower resolutions eventually.</p>
  
  <p>I have been using <code>ffmpeg</code> for all my video processing activities so far, and would simply approach this task using the following command:</p>
  
  <p><code>ffmpeg -i tos.mov -vf scale=-1:720 tos_0x720.mov</code></p>
  
  <p>I understand that this will rescale my video to a new frame size having 720 pixels set as a fixed height and the width dynamically calculated.</p>
  
  <p>What I am not sure about are the implications regarding the quality factors of the video when using <code>ffmpeg</code> this way. </p>
  
  <ol>
  <li>Is it valid to assume that running this command will output a perfect HD 720p quality video?</li>
  <li>What would be a benefit of using dedicated video conversion software to accomplish my goal compared to running the above command?</li>
  </ol>