title: using edeD3 to change encoding of mp3 tags
body: <p>I found <a href="https://stackoverflow.com/questions/2190904/how-to-correct-the-misencoded-string">this question</a> which is my exact starting point: Chinese-encoded metadata on mp3 files. I want to re-encode all my metadata as utf-8 so that Banshee can read it.</p>
  
  <p>I can't figure out how to get eyeD3 to do that. I can decode individual tags as per that previous link, but I can't make eyeD3 change the actual text encoding of the mp3 file itself, so those tags can be rewritten in the proper encoding. I tried reading all the data into variables (below, 't' is the properly encoded title), then calling:</p>
  
  <pre><code>tag.clear()
  tag.update(eyeD3.ID3_V2_4)
  tag.setTitle(t)
  </code></pre>
  
  <p>That tells me: <code>ValueError: ID3 vNone.None is not supported.</code> Not what I was expecting.</p>
  
  <p>I tried <code>tag.setTextEncoding('utf-8')</code>, but that tells me <code>eyeD3.tag.TagException: Invalid encoding</code>. All the other encodings I try give me the same error message.</p>
  
  <p><code>eyeD3.TAGS2_2_TO_TAGS_2_3_AND_4</code> looks promising, but it's a dictionary of cryptic letter codes that mean nothing to me.</p>
  
  <p>Can someone tell me how to change the version of the tags to something that supports utf-8, then change the file encoding to utf-8 and write the metadata back in?</p>