title: MP4Box: Concatenating track ID 1 even though sample descriptions do not match
body: <p>Essentially, I wish to concatenate a series of videos using MP4Box. When I attempt to do so, I receive the following error:</p>
  <pre><code>No suitable destination track found - creating new one (type soun)
  0.500 secs Interleaving 
  </code></pre>
  <p>I can circumvent the issue, at least temporarily, by adding a <code>-force-cat</code> parameter to the <code>MP4Box</code> command. However, this creates issues with the alignment of audio and video and produces the following warning:</p>
  <pre><code>Concatenating track ID 1 even though sample descriptions do not match
  </code></pre>
  <p>Now, as far as I can tell, this has to do with differing parameters between video types. I will display the <code>ffprobe</code> output of each video type below in order to hopefully shed some light on the issue.</p>
  <p><strong>VIDEO TYPE 1 FFPROBE OUTPUT:</strong></p>
  <pre><code>Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '0.mp4':
    Metadata:
      major_brand     : isom
      minor_version   : 512
      compatible_brands: isomiso2avc1mp41
      encoder         : Lavf58.29.100
    Duration: 00:00:02.25, start: 0.000000, bitrate: 851 kb/s
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 816 kb/s, 4 fps, 4 tbr, 16384 tbn, 8 tbc (default)
      Metadata:
        handler_name    : VideoHandler
      Stream #0:1(und): Audio: mp3 (mp4a / 0x6134706D), 24000 Hz, mono, fltp, 32 kb/s (default)
      Metadata:
        handler_name    : SoundHandler
  </code></pre>
  <p><strong>VIDEO TYPE 2 FFPROBE OUTPUT:</strong></p>
  <pre><code>Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'static.mp4':
    Metadata:
      major_brand     : isom
      minor_version   : 512
      compatible_brands: isomiso2avc1mp41
      encoder         : Lavf58.78.100
    Duration: 00:00:01.00, start: 0.000000, bitrate: 662 kb/s
      Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 654 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
      Metadata:
        handler_name    : VideoHandler
  
  </code></pre>
  <p>Can anyone identify what the incongruity between video types is and how I can resolve it? Thanks.</p>