How does Google Play Music identify mp3 file?

Question

In Blind Guardian song Curse my Name, there is a high pitched beep that ruin the song. (This is a well known issue, you can read about it here). I fixed the song using audio editor but now, I can't upload it to Google music.

What I did :

• Right click on "old" song, delete this song.
• Using Google Chrome, I upload the "fixed" song by drag and dropping it in the Google music window.
• Once the upload finished, I go to "Latest upload" automatic playlist, and there the song is the deleted one that has been restored.
• I deleted it again
• I edited the mp3 ID3 tags (hopping that Google music will identify the song as a new one)
• Re-uploaded, same result. The old deleted song is restored.

How can I upload my edited version of the song?

Edit: I finally managed to upload it with the Google music manager client and Firefox, but I'm still curious to know how does Google music identify the mp3 file.

Answer 1

First: did you also remove the song from Google Music recycle bin, after deleting it from your library?

There is a chance that if you upload a song that Google Music is recognizing as the same as the one you deleted, it will restores it from recycle bin, if it's still in there.

I don't know if you know already but this is how Google Music works:

when you try to upload a song it will try to "Scan and Match" it to its catalogue of songs by comparing the waveforms (sort-of).

• if there is a match it will not let you upload the song, but it will add a high quality (320 kbps) version of that song to your library (for streaming only: later on if you try to download that song to your computer it will send you a version with the closest bitrate to the one you tried uploading).

• if there is no match then your file will be uploaded and retain the quality it has been encoded at (obviously)

So I guess what was happening in your case was that when you were uploading the tone-clean song, either Google was restoring the song from its recycle bin or, in case your removed it from the bin as well, Google Music was probably still matching the tone-cleaned song with the original song (containing disturbing tone) from their catalogue and adding that to your library again.

Also, this answer to a similar question can also be useful in understanding what was going on.

I don't know how exactly you managed to upload the tone-corrected song with Firefox, but I am quite confident that the reason it worked had more to do with a mix of the factors I explained above than with something else.

I hope it helps, if not for this case, maybe for future ones.