How do I access the mp3 files which exactly correspond to the entries in the database? How confident can I be that a random mp3 file whose name, artist etc matches with an entry in MusicBrainz refers to the same file?
MusicBrainz is a database of metadata, not a database of audio files. If you have a random mp3 file, implying you didn’t rip it or buy it yourself, then there’s no reliable way to know what it corresponds to.
If you have a heap of random MP3 files, randomly tagged, from random sources, then you are working on a level of “best guess”. I don’t know what stats say, but you are likely to be on a 90% and above at naming the recording. But a much lower chance of knowing exactly which album\single that recording was from.
Scan in Picard will used AcoustID to find places that track may be found, but you’ll need to then check the recoding in the main database. There is no way for Picard to know if your track came from a Single, the Album or a Various Artist compilation.
Lookup uses the tags in your mp3 to try and find a match and more likely to find the album.
If you want accuracy, you also want to check the lengths of your recordings. AcoustID is not perfect, but it will give you a pretty good guide. You will still need to check results.
What you don’t want to do it load up hundreds of recordings and hope it will get it right every time.
Also what you really don’t want to do it hit that “Submit AcoustID” button as it is not the button you want at all.
AcoustID only checks the first 120 seconds (and not all that well), so it’s still not a good idea if the user doesn’t know where the mp3 files came from.
AcoustID may not be perfect, but it is pretty good at sorting out a tangled heap of music files. If they are a mess of badly tagged data, then setting Picard’s bias to singles and albums it will make the mess a less of a mess.
It may be madness to some of us that someone may not want to know which exact CD their music came from, but if all they want is some order to their chaos it will help them.
I always say “backup before you start” to anyone. But I don’t drive them away from attempting to use these tools.
There is no confidence for a such “random mp3 file”. Everyone can name a file with whatever he/she wants. Completely matching or completely random.
In addition to all the points already mentioned above, you can only increase your trust in your mp3 file if you already know the song and if you recognize it when you play it.
You will still not be sure if this is the song from a Single, Album, Best Of or one of the many Sampler out there. But you can say with a fairly high probability if it is a song from AC/DC or from ABBA.