title: Creating video from images produces black screen video for certain image formats
body: <p>I am using below command to create video from images.The command works fine for most images but for png images the video created cannot be played and I just get a black screen.</p>
  
  <pre><code> String[]  command = new String[]{"-y", "-f", "concat", "-safe", "0", "-i", src.getAbsolutePath(), "-vsync", "vfr", "-vf", "scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2", dest.getAbsolutePath()};
  </code></pre>
  
  <p>Here destination file path has mp4 format..
  Whats wrong with my command?</p>