I have a rather large vinyl collection, some of which i have recorded to mp3 and added to my iTunes collection over the years.

I have noticed that some of them are not being matched, and i am wondering what the cause is.  I have updated the track and album info, but it still doesnt match. 

For example...

In my collection (notice it says uploaded, not matched) -
![enter image description here][1] 

and in the store -
![enter image description here][2]

It located and downloaded the artwork, yet it still wont match.

I understand from reading [this question][3] that it uses gracenote for matching, which may read parts of the waveform.  Surely the waveform of my vinyl recording is the same, regardless of gain level?  

One thing i have noticed is that my recording is 16 seconds longer - maybe this could be the issue?


  [1]: https://i.sstatic.net/x789y.jpg
  [2]: https://i.sstatic.net/4z6qo.jpg
  [3]: http://apple.stackexchange.com/questions/31466/how-does-itunes-match-match-the-songs-in-your-library