I use Mp3tag for tagging and WMP 11 for listening. Most of my files are mp3.
Somewhen WMP reads tags incorrectly, so I decided to repair. I cleared all files from WMP library. Cleared all tags in Mp3tag and pasted them back. Then imported all files into WMP library again with turned on option "Analyze files to store loudness level normalisation data" (it took 12 hours...). This function work well in WMP (if turn it on at playing).
I use tags ID3v2.3 UTF-16. After this procedure I opened my files in Mp3tag and see: all files have ID3v2.3 ISO 8859-1 AND ID3v1 tags (what encoding, I don't know). I think, WMP can rewrite tags only for 2 purpose: get (all or more) info from net - but this option is turned off; or write replay gain data - but I couldn't find any RG tags in files. I tried sequently, step by step clear the tags (because one tag may hide the other), but found nothing.
Wikipedia write that WMP use RG data. I searched the net, how and where but found nothing. In tags? No RG tags I could find. Anywhere in the file, in other place? In separated database? If db, where it is? In earlier versions of WMP (9? 10?) there was an option to save library data, so was a database - but this option is missing in WMP 11.
I plan to rewrite tags back using Mp3tag: copy, delete, paste back. But: is there a risk to loss WMP's RG data in this way, or not? And the other: how about RG in case of importing FLACs to WMP library?
Well, I did a test. Found a very quiet file, so I can exactly hear the result of turning on/off volume normalisation in WMP. I cleared and pasted back tags with Mp3tag, as I plan with all files. Opened again in WMP: RG data is still there, normalisation works. But I'm still interesting, how is it stored in WMP.
And have an other question. While plays this very quiet song with normalisation turned on (so loudness will extremely higher) I hear strong crackles. Why? Is there a way to avoide?
OK, I couldn't find on the net, but found in WMP Help : RG data is stored in a file.
Still don't know, why WMP rewrote the tags, and what to do with crackles.