THE LIVES of influential musicians make troublesome but irresistible grist for Hollywood movie mills. Charlie Parker, Ray Charles, Selena, Buddy Holly, Jacqueline du Pré, Eminem and 50 Cent have all been immortalized on film. Timeless musical legacies combined with the ready-made sensationalism of pop-culture fame can add up to high drama, but music biopics have a millstone in the form of pre-existing fans and their expectations. Part of being a musician today involves becoming a larger-than-life media figure, which adds up to a tall order for an actor. Is it better to imitate the subject or evoke the essence of the subject? Should the actor sing or lip-sync? These issues have been very much on my mind as the Johnny Cash/June Carter biopic Walk the Line (starring Joaquin Phoenix and Reese Witherspoon) nears its Nov. 18 theatrical release. Like many fans, I feel protective of Johnny and June's legacy. But fretting over the accuracy of a feature film is also a welcome respite from brooding over earthquakes, flu pandemics and hurricanes. To brace myself for things to come and indulge in a week of escapist therapy, I left the video store with an armload of rentals and pondered the mechanics of the music biopic.

A good music biopic churns with energy, conjuring up the delights of life on the road and the demons of fame, while a bad music biopic drags a musician's buoyancy down with leaden pacing and poor casting. For purposes of cohesion, scripts omit details, rearrange timelines, consolidate lovers and spouses, and overemphasize dramatic characteristics over boring but amicable ones. Screenwriters face the challenge of bending a life into a satisfying arc—that is, there's a beginning, a road to discovery and a resolution. Some music biopics are too ambitious for their own good (Beyond the Sea), some stall at the box office from general lack of public interest (Why Do Fools Fall in Love) and some swell into more of a fantasia than a dramatization of actual events (Sid and Nancy). But they often share filmmaking conventions, such as the opening flashback of the pivotal moment that presages the main figure's undoing; the scene illustrating the creative birth of a signature song; the concert performance montage alluding to blossoming success; the downward spiral depicted during another, darker performance montage; the death; the demonstration of the artist's impact. Let's take a look at some great successes, failures and fizzlers of the genre to see where a film can go wrong or right.

Lady Sings the Blues (1972) There's no better example of how a biopic can flounder because of miscalculated casting. This Diana Ross vehicle (produced by Motown mogul Barry Gordy) mucks up Billie Holiday's notoriously rough and tragic life with a convoluted script, but the main problem is Diana Ross. The real-life Billie Holiday had a formidable physicality to her presence; she may have been emotionally vulnerable, but she could beat the crap out of you if she wanted. Ross, such a sylph of a thing, simply cannot overcome her own star power, and the viewer is constantly aware of her fabulous Miss Ross-ness. With the best of intentions, Ross handles the part like a 12-year-old girl playing dress-up, flouncing and flopping across the set. The resulting movie, with its bloated screen time and generous liberties with Holiday's admittedly cloudy biographical details, is nearly unwatchable. Saving grace: Bob Mackie's foxy, Oscar-winning costumes, which look great on Ross' slender frame.

The Doors (1991) This movie came out my first year of high school, and I thought it was the bee's knees. But 14 years of perspective can do a lot to ruin the idealism of both schoolgirls and Oliver Stone. There are a lot of annoying things about this movie, and most of them have to do with its director. As we see Val Kilmer's Jim Morrison pack on the pounds from a few hundred too many bottles of Jack Daniels, Stone's film likewise grows more bloated and aimless; concert scenes bleed into stoned monotony. There's only so much of Jim musing on death and trying to kill his muse (Meg Ryan) that an adult viewer can take. Native Americans keep popping up from nowhere, and the multiple hazy-lensed, acid trip sequences border on campy. Even so, Val Kilmer gracefully evokes Morrison's lewdly feline and menacing stage presence. Original Doors recordings threaded together throughout provide a tonic to exasperated viewers. If you can't watch, hey, you can always listen.

La Bamba (1987) Ritchie Valens was 17 when he boarded the ill-fated airplane on the Day the Music Died, and his career as a rock & roll sensation was even younger; in the span of eight months, Valens delivered the hits "Come On, Let's Go," "Donna" and "La Bamba." This little film sticks very much to formula, but it keeps its focus tight and delivers a solid, if not great, movie. The soundtrack is utterly devoid of Valens' original recordings, favoring instead Los Lobos' spirited updates. As the young Valens did not meet his undoing via chemical vices, director-screenwriter Luis Valdez instead mines a good brother/bad brother relationship for dramatic fodder to touching effect.

Coal Miner's Daughter (1980) The straightforward story line of this sweet film sticks quite closely to the details that Loretta Lynn laid out in her chatty 1976 autobiography. As Lynn, Sissy Spacek handles the vocal duties, and in the process eerily channels Lynn's spark. Flexing her malleable acting chops, Spacek is as convincing as the 13-year-old Butcher Hollow Loretta as she is the bouffant-crowned, granny-gowned Nashville Loretta of the 1970s. Lynn's health problems (migraines, physical exhaustion) stand in for the standard biopic convention of street drugs, but there's menace to spare in the form of her devoted but dogmatic husband, Doo (Tommy Lee Jones). Free from flashback sequences and including only one performance-montage, Coal Miner's Daughter puts on no airs—just like Loretta Lynn.

Backbeat (1994) The Beatles must be the Holy Grail of biopic subjects, but there's the small problem of them being the most famous band in the world; they essentially played out their own biopic on a world stage. Backbeat takes the clever approach of setting the movie in the era Beatles most fans are less familiar with (seedy, pre-fame Hamburg days) and to center the story not on the band itself but on the dynamic between John Lennon, Stuart Sutcliffe and Stuart's lover, Astrid. Backbeat features not one Lennon-McCartney tune, a move that infuses the film with credibility and freshness. Punk/alt-rockers Mike Mills, Dave Grohl, Thurston Moore, Gregg Dulli and Dave Pirner made up the ad hoc band that recorded the soundtrack and the result seethes with the raw rock energy that present-day Beatles fans can only dream of, winsomely conjecturing what it felt like to hear the promise and hope in band when they were still paying their dues.

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