I have this mistery that happened to me recently with my MP3 files. I had a few MP3s that should be identical, but as I have discovered, those files doesn't seem to be identical by their content. I have tried many tools for comparison of the files, but all of them gave me the same result - those files seemed to be different. When I looked at those files with MediaInfo, it appeared as if those files were the same. They had the same tags, same content (when comparing in Audacity) and overall I haven't noticed anything weird about it.
The last thing that came to my mind is to put these files to the diff tool. I have utilized the command
colordiff --side-by-side --suppress-common-lines -y <(xxd file1.mp3) <(xxd file2.mp3)
and got an interesting result. The output of the diff was following:
00000000: 0b08 0000 0000 3402 0002 fffa 52c0 268d ......4... | 00000000: 0b08 0000 0000 4403 0002 fffa 52c0 268d ......D...
Weird... a single 16-bit value difference. This is the only difference when comparing two files which should be identical. When comparing the whole file, the output got really messy, so I'm not sure from where this particular line came, but I guess it belongs to the file header, because I don't think the content of the MP3 would get modified, rather I do suspect the metadata.
Other than this info I'm not really sure what can cause this, but I thought it is wort a shot to share this issue with StackOVerflow to find out more. Thank you for all your replies, I will try to provide any further details if needed.