title: Shifting audio in MPEG4 content and manipulating atoms
body: <h2>1. Shift audio</h2>
  
  <p>I use <strong>ffmpeg</strong> / <strong>avconv</strong> quite often ... and usually I hate it.
  Those tools do what they are instructed to do about 30% of the time. I could give you countless examples but I don't want to start flame war, so please help me with my current problem (really easy one).</p>
  
  <p>I wanted to shift audio (content is standard mp4 file with aac and h264 tracks), so I have found a "highly upvoted" solution:</p>
  
  <p><a href="https://superuser.com/a/983153/758887">https://superuser.com/a/983153/758887</a></p>
  
  <p>the only problem with it is that it doesn't work. I downloaded latest stable ffmpeg (even on windows as in the thread, so it's version was 3.4.1) and executed command without changing literaly anything:</p>
  
  <pre><code>ffmpeg.exe -i "movie.mp4" -itsoffset 3.84 -i "movie.mp4" -map 0:v -map 1:a -vcodec copy -acodec copy "movie-audio-delayed.mp4"
  </code></pre>
  
  <p>Result was no shift (I expected audio to be 3.84s late).</p>
  
  <h2>2. Remove MPEG4 atoms</h2>
  
  <p>I would be also grateful if you could recommend some tool for removing MPEG4 boxes from content. For examining MPEG4 content I use <strong>MP4 Explorer</strong> / <strong>Codec Visa</strong> (limited) on Windows and <strong>AtomicParsley</strong> on Linux, however they only print atoms and I would like to edit / remove them. For example <strong>MP4Box</strong> can remove whole moov->track with "-rem" option but what if I would like to remove moov->track->edts only?</p>