title: Checking video length in moviepy without rendering it
body: <p>I want to create a python script what would show images for X seconds (the time until the audio goes), then go to the next image. I want the video to be X long. The lenght of the video will be always different cause of the audio. Anything that I can check the lenght of the unrendered video? My code:</p>
  <pre><code>from moviepy.editor import *
  
  img = ['1.jpg']
  
  clips = [ImageClip(m).set_duration(2)
        for m in img]
  
  
  clip = VideoFileClip(&quot;test.mp4&quot;)
  print( clip.duration )
  if clip.duration &gt; 601:
      print(&quot;clip is longer than 10 min&quot;)
  else:
      print(&quot;clip is shorter than 10 min&quot;)
  
  vid_clips = concatenate_videoclips(clips, method=&quot;compose&quot;)
  vid_clips.write_videofile(&quot;test.mp4&quot;, fps=60)
  </code></pre>