The album format may be on the wane, but album of the year remains the big enchilada at the Grammy Awards.

Nominating ballots for the Recording Academy’s 55th kudofest — covering releases issued between Oct. 1, 2011 to Sept. 30 — were due Oct. 31. Nods in the top categories will be revealed during a CBS special on Dec. 5, with the awards show set for Staples Center in downtown Los Angeles on

Feb. 10.

With the finish line looming, it’s a perfect time to survey the album landscape. As ever with the Grammys, potential nominees fall into some tradition-bound categories.

The Big (Commercial) Guns

The Grammys purportedly salute artistic achievement, but — since the National Academy of Recording Arts and Sciences draws its membership from music industry pros — chart placement and sales of the year’s best titles inevitably come into play, as they did with Adele’s triumphant “21” in 2012. With album sales flagging this year, only a few titles apply. (Taylor Swift’s mega-selling “Red” was released too late to qualify.)

An apparent sure thing is Lionel Richie’s “Tuskegee.” The R&B veteran’s collection of duets with country guests became his first No. 1 album in 26 years, and is the second-bestselling title issued this year with more than 1 million shifted. The Academy’s nostalgia-prone voters (and, in a thin year for country albums, some of its Nashville contingent) are likely to give Richie — who took album of the year in 1985 with “Can’t Slow Down” — a thumb’s up.

Mumford & Sons’ sophomore release “Babel” had the year’s biggest debut (600,000 copies) just before the end of the nominating year in September, a huge boost for the U.K. folk rockers. Less likely to prevail, despite sales approaching 1.3 million, is lightweight U.K. boy band One Direction, who may have to be satisfied with a best new artist nomination.

The Hip-Hop Factor

A pair of big rap entries seem like obvious Grammy choices this season. “Orange,” the full-length solo debut by Odd Future posse member Frank Ocean, was among the year’s best-reviewed collections and ascended to No. 2 on the U.S. album chart.

Ocean might face stiff competition from Canadian rapper Drake, however. His late-2011 sophomore album “Take Care” entered at No. 1 and has moved 1.9 million copies in the interim. The former best new artist nominee (who lost out to dark horse Esperanza Spalding in 2011) can’t be taken lightly.

Diva Face-Off

A couple of R&B/hip-hop performers with Grammy track records could make an appearance this year. Possessing glamour, a strong work ethic and a 2012 nomination for “Loud,” four-time winner Rihanna could repeat in the category with her million-selling late 2011 entry “Talk That Talk.”

However, Rihanna’s erstwhile collaborator Nicki Minaj — a former best new artist nominee — may make her mark with her second album “Pink Friday: Roman Reloaded.” While response to the set was mixed, Minaj is a hot-button personality thanks to her “American Idol” profile; she appeared in an eyebrow-raising production number during the 2012 Grammys ceremony.

Those About to Rock

Rock music is still good for at least one pick among the album finalists, but this year’s field contains no single release that found great commercial or critical favor (unlike the most recent rock album of the year winner, Arcade Fire’s “The Suburbs”). With NARAS darlings Foo Fighters now officially on hiatus, the rock slot will be up for grabs in the immediate future.

Besides Mumford, contenders include Coldplay’s “Mylo Xyloto,” the Black Keys’ “El Camino,” the Dave Matthews Band’s “Away From the World” and newcomer Alabama Shakes’ “Boys & Girls” (though the latter act will likely place in the best new artist field).

The Vets

The Recording Academy loves a strong performance by a time-tested artist (see Lionel Richie above), and this year saw powerful chart placements and great critical response to new works by several of the best-known artists in the business.

Bruce Springsteen, whose “Wrecking Ball” was his eighth No. 1 studio album, is an industry Brahmin. The recording was a strong election-year statement that preceded a wildly received E Street Band tour, and one of its tracks, the inspirational “Land of Hope and Dreams,” was the inescapable TV theme of Major League Baseball’s post-season.

Moreover, the Boss — who has won 20 Grammys, but never album of the year — will be feted as MusiCares’ Person of the Year two nights before the ceremony.

Bob Dylan’s “Tempest” received fine reviews in some quarters, and was his fifth top 10 album of the last 15 years, an excellent showing in his autumnal years.

Amid a lately renascent career, 78-year-old Canadian Leonard Cohen made his highest U.S. chart showing to date when “Old Ideas” entered at No. 2.

And Bonnie Raitt, whose memorable four-Grammy night with “Nick of Time” in 1989 is vividly recalled by voters, captured attention with her indie release “Slipstream.”