AcoustId currently has about 63M acoustids, MusicBrainz has about 25M recordings, so clearly there are many tracks in Acoustid that do not have a corresponding track in MusicBrainz
When Acoustids are submitted the basic metadata is stored with I have been looking at this data and have been able to create Acoustid Albums from the metadata. The report contains about 400,000 albums that we have been to construct data and do not seem to be in MusicBrainz.
The reports let you look at potentially missing albums and import them into MusicBrainz, click on Show Tracks to see the tracks in the release and Import Release to seed the MusicBrainz release editor with the basic data.
I’ve split into three reports, based on how many existing releases the artist has in MusicBrainz.
So the first one is musicbrainz artists that are already featured on more than 100 releases so I expect most people will recognize the majority of artists in the list, and alot of the missing releases are live albums, and also many classical releases. This report is more likely than the other two to list albums that are already in MusicBrainz but just with a slightly different name.
http://reports.albunack.net/acoustidalbums_report.html
The second is artists with between 2 and 100 releases, so these are smaller artists, and there are more missing original studio release but also plenty of live albums
http://reports.albunack.net/acoustidalbums_medium_report.html
The third is artists with one release or left, these are the really obscure artists, probably mainly self published releases.
http://reports.albunack.net/acoustidalbums_low_report.html
Added View in Albunack button, this is a discography page comprising combined MusicBrainz and Discogs releases for an artist and links and potential links between the two. If you are reviewing a particular artist it is often worth looking at this because the same release may also be in Discogs and this page allows you to import/seed the release from Discogs. Since Discogs usually has better metadata including coverart it is usually better to import from Discogs rather than direct from Acoustid
Album Artist link takes you to the MusicBrainz Artist page for that artist, but only a link if that is the only artist with that case-insensitive name in MusicBrainz, because if there are multiple artists with same name we cant reliably identify the correct one.
If SongKong or Jaikoz is failing to match albums then this provides an easy way to add some of those albums to MusicBrainz without much effort. And because MusicBrainz it is a collaborative effort once you have added the initial release then other MusicBrainz editors are likely to help to improve the details over time.