title: Synthesia plays well midi file without any note off event?
body: <p>I have a <code>.mid</code> file - <a href="https://pastebin.com/amkth128" rel="nofollow noreferrer">this</a> one specifically. Appart from the header chunk here is the relevant part of the midi. The first track chunk contains only meta events and is described as</p>
  
  <pre><code>4D 54 72 6B 00 00 00 52 // Track chunk #1 info
  
  00 FF 58 04 04 02 18 08 // Meta event
  
  00 FF 59 02 00 00 // Meta event
  
  00 FF 51 03 15 CC 5B // Meta event
  
  81 88 70 FF 51 03 16 E3 60 // Meta event
  
  81 70 FF 51 03 1A 28 6E // Meta event
  
  81 70 FF 51 03 1C 9C 38 // Meta event
  
  81 70 FF 51 03 1E 84 80 // Meta event
  
  81 70 FF 51 03 20 B2 89 // Meta event
  
  81 70 FF 51 03 23 36 6C // Meta event
  
  81 70 FF 51 03 2B 98 B7 // Meta event
  
  00 FF 2F 00 // Meta event. End of track #1
  </code></pre>
  
  <p>This is the second track chunk, wich contains only <em>Note on</em> events:</p>
  
  <pre><code>4D 54 72 6B 00 00 04 02 // Track chunk #2 info
  
  00 FF 21 01 00 // Meta event
  
  00 FF 03 1F 53 69 6E 66 6F 6E 69 
  61 20 66 72 6F 6D 20 4B 61 6E 74 61 74 61 20 23 
  31 30 36 20 2D 4A 53 20 // Meta event
  
  00 C0 4A // Midi event
  
  00 B0 07 7C // Midi event
  
  00 B0 0A 52 // Midi event
  
  00 B0 5B 4B // Midi event
  
  96 40 90 4B 50 // Midi "Note on" event
  
  81 63 4B 00 // Midi "Note on" event because of running status 
  
  ... // No note offs event in this track chunk.
  
  FF 2F 00 // Meta event. End of track #2
  </code></pre>
  
  <p>This is track #3:</p>
  
  <pre><code>4D 54 72 6B 00 00 03 27 // Track chunk #3 info
  
  ... // Some meta and non-note-on, non-note-off midi events
  
  96 40 91 4B 50 // "Note on" event
  
  81 63 4B 00 // Another "Note on" event
  
  ... // No note offs
  
  FF 2F 00 // End of track #3
  </code></pre>
  
  <p>Track chunk #4, #5 and #6 have the same structure as #3; #7 contains two meta events only.</p>
  
  <p>Note that every track chunk which doesn't contain only meta events starts with two <em>Note on</em> events, and no one of them contains a single <strong>Note off</strong> event.</p>
  
  <p>But this is what synthesia (a midi player) sees when loading the file, just at the start of the song:</p>
  
  <p><a href="https://i.stack.imgur.com/LU1dJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LU1dJ.png" alt="Synthesia capture"></a></p>
  
  <p>The structure of this midi would be a <em>Note on</em> event followed by a <em>Note off</em> event in the same track chunk, but this doesn't happen.</p>
  
  <p><strong>What's happening here?</strong></p>