title: MP3 bitrate detection through frequency spectrum analysis
body: <p>Is there any program that detects the bitrate of an MP3?
  I'm not talking about the effective bitrate that the file has been encoded with, but the real bitrate that can be calculated only by frequency spectrum analysis.</p>
  
  <p>For example, if I have an MP3 encoded in 128 kbps whose size is 1 MB, and then I transcode this MP3 to 320 kpbs whose size becomes 3 MB, I will have the same identical audio track, but with different sizes.</p>
  
  <p>If I have a 320 kbps MP3 and I transcode it to 128 kbps I will lose some quality and therefore some file size.</p>
  
  <p>But still, I have no way to verify that 320 kbps is my MP3's "real" bitrate.</p>
  
  <p>Details are explained in this paper:
  <a href="http://www.fileden.com/files/2009/2/14/2321055/My%20Documents/MP3%20Bit%20Rate%20Quality%20Detection%20through%20Frequency.pdf" rel="nofollow noreferrer">http://www.fileden.com/files/2009/2/14/2321055/My%20Documents/MP3%20Bit%20Rate%20Quality%20Detection%20through%20Frequency.pdf</a></p>