Eastwood is indeed a music maven, as he demonstrates again this week by producing and hosting Johnny Mercer: The Dream's On Me (Wednesday at 8 p.m. ET, Turner Classic Movies). It's the kickoff for a month's tribute to the swingin' songwriter and sometime singer behind "Blues in the Night," "One for My Baby," "Jeepers Creepers," "Hooray for Hollywood," "Moon River" and other classic film tunes.

The Mercer marathon is just one of TCM's November salutes, which also include a Thursday night showcase for actress Grace Kelly. But the look at Mercer's work is especially interesting, now that songs in current films serve mostly as record company deals or commercial ephemera.

Tunes in Hollywood's studio era were used more emotionally -- and eternally -- as this 100th birthday celebration so amply demonstrates by unreeling 25 movies Mercer helped make famous and/or effective. TCM follows up Eastwood's feature-length documentary with the bold and brassy sounds of 1942's wartime songfest The Fleet's In (Wednesday at 10 p.m. ET, with Dorothy Lamour and the indefatigable Betty Hutton) and 1954's macho musical Seven Brides for Seven Brothers (late Wednesday night at 2 a.m. ET, after a midnight repeat of the Mercer bio).

But I'm more inclined toward the moody musical signature of 1941's Blues in the Night (late Wednesday/early Thursday at 3:45 a.m. ET, all on TCM).

The mournful title motif with lyrics by Mercer and music by Harold Arlen ("Over the Rainbow") runs throughout this underrated portrait of a jazz band on the road and on the skids. It's boldly directed in black-and-white by Anatole Litvak (Sorry, Wrong Number) as an almost expressionistic dive into an underworld of nomadic players, mob muscle and music's motive power. Don Siegel (later to direct Invasion of the Body Snatchers and Eastwood's Dirty Harry) cut the montages that fast-forward the story, and the cumulative effect is summarized by one IMDb reviewer who calls Blues in the Night "both a musical drama and a sort of missing link between the Warners gangster movies of the 1930s (mugs, molls, and rat-a-tat dialogue) and 1940s film noir (femme fatale, dark shadows, smoky atmosphere, seamy underside of life)."

(But why are TCM's coolest flicks always on in the middle of the night?)

Blues in the Night also captures the loose yet devoted musical vibe that powered Mercer's writing, and his singing, too. It was the laidback latter that drew composer John Williams to his work, he tells Eastwood in TCM's documentary, which includes testimony from fans ranging from Tony Bennett and Julie Andrews to Michael Feinstein to (eek) Eastwood's teen daughter, Morgan. Vintage Mercer interview footage is woven alongside clips of his performances in movies and on the '50s-'70s TV shows of Rosemary Clooney, Andy Williams, Merv Griffin and Dinah Shore.

Mercer's life influences are keenly sketched, from his Revolutionary War ancestors (whence the name of New Jersey's Mercer County) to his own Georgia "country boy" upbringing. Even Mercer's place in literary, cultural and improvisation traditions is explored, placing him in the American giants pantheon of Mark Twain and Louis Armstrong. You can't say Johnny Mercer: The Dream's On Me isn't a well-rounded portrait, of both the man and his music.

There's more Mercer here with details of TCM's Wednesday screenings. Grace Kelly's Thursday run is outlined here.

And you can now plan your TCM tribute viewing with the new half-hour teaser Now Playing: The Show (Sunday, Nov. 8 at 6 a.m. ET, TCM), an on-air companion to the channel's indispensable printed monthly guide Now Playing (subscribe here).