title: Advice for decoding binary/hex WAV file metadata - Pro Tools UMID chunk
body: <p>Pro Tools (AVID's DAW software) has a process for managing and linking to all of it's unique media using a <code>Unique ID</code> field, which gets embedded in to the WAV file in the form of a <code>umid</code> metadata chunk. Examining a particular file inside Pro Tools, I can see that the file's <code>Unique ID</code> comes in the form of an 11 character string, looking like: <code>rS9ipS!x6Tf</code>.</p>
  
  <p>When I examine the raw data inside the WAV file, I find a 32-byte block of data - 4 bytes for the chars 'umid'; 4 bytes for the size of the following data block - 24; then the 24-byte data block, which, when examined in Hex Fiend, looks like this:</p>
  
  <blockquote>
    <p>00000000 0000002A 5B7A5FFB 0F23DB11 00000000 00000000</p>
  </blockquote>
  
  <p>As you can see, there are only 9 bytes that contain any non-zero information, but this is somehow being used to store the 11 char <code>Unique ID</code> field. It looks to me as if something is being done to interpret this raw data to retrieve that Unique ID string, but all my attempts to decode the raw data have not been at all fruitful. I have tried using <a href="https://gchq.github.io/CyberChef/" rel="nofollow noreferrer">https://gchq.github.io/CyberChef/</a> to run it through all the different formats that would make sense, but nothing it pointing me in the right direction. I have also tried looking at the data in 6-bit increments to see if it's being compressed in some way (9 bytes * 8 bits == 72 == 12 blocks * 6 bits) but have not had any luck stumbling on a pattern yet. </p>
  
  <p>So I'm wondering if anyone has any specific tips/tricks/suggestions on how best to figure out what might be happening here - how to unpack this data in such a way that I might be able to end up with enough information to generate those 11 chars, of what I'm guessing would most likely be UTF-8.</p>
  
  <p>Any and all help/suggestions welcome! Thanks.</p>