The must-watch movie on the crystal flatscreen parked in the corner  of your living room this week? There’s no second guessing, says Richard Lutz

Sometimes, it seems, you can’t move for music bio-pics. Especially ones that etch portraits of famous folks whose lives descend into turmoil or self destruction. Sadly, it’s the bread and butter of film narrative in this genre.

Think about it. Who’d really want to pay cash to see a movie about a guy or girl who went to the recording studio, sang songs, got back into the car, went home and tidied up the kitchen or double-checked a gas bill?

Actually, it sounds akin to what Warhol would have produced in a ten hour saga with a static camera.

Aside from that, think of recent movies that painted the lives of Joy Division’s Ian Curtis, Jimi Hendrix, Edith Piaf, Miles Davis, Jim Morrison, Hank Williams, Ray Charles. All of them commendable. But what do you get out of it, except a re-write of (pick a leitmotif) drugs, drink, loneliness, struggle and more drugs and drink?

But the documentary Janis: Little Girl Blue (Friday, BBC4, 22.30) does at least try to break the mold.

Yes, it is about mega-rock singer Janis Joplin, who died of an overdose after three meteoric albums and loads of brilliant if erratic stage shows. But what makes this different is the film, directed by Amy Berg, uses Joplin’s letters home as a structure to better understand the blues singer who died at only 27.

Joplin wrote to her family every week back in Texas during her unknown, and then infamous , days on the west coast. They are simple letters to her parents and her brother and sister, and they’re read out by singer Cat Power, a southern musician with her own idiosyncratic career.

Director Berg fleshes out the correspondence from Joplin, sometimes illuminating and sometimes a matter of small familial chitchat, with stock-in-trade interviews. But what a list: Big Brother band  members Sam Andrew and Peter Albin, Grateful Dead guitarist Bob Weir, Kris Kristofferson and Joplin’s siblings, looking for all the world like nice decent folks who you’d engagingly bump into in your local supermarket or suburban shopping mall.

Plus there is excellent, and some unseen, archive from the heady late sixties including an innocent and stoned interview with late night chat show host Dick Cavett who admits, sweetly, that he may, just may, have been in love with this outsized queen of rock blues.

So, a small screen classic that seemed to be missed when first distributed last year. I mean, what else have you got to do (in the UK anyway) if you’re glued to the box with no date on a Friday night? At the same time, you have lazy repeats of Ice Truckers, The Big Fat Quiz of Everything (sic), yet another replay of a squishy Bridget Jones saga, or, on the Welsh speaking channel S4C, something called Wmff which, probably, is Welsh for….Wmff.