Is the rockumentary making a comeback?

It was in LA's Viper Room club in 1996 when Ondi Timoner realised that, as she puts it, "something was terribly wrong". Until then, everything had been smooth and fairly unremarkable. A self-taught 21-year-old filmmaker, she had been "seeking to make a film about art and commerce", and had decided to focus on the music industry. Initially, she attempted to film 10 bands, but one seemed more obviously destined for success than the rest.

The Brian Jonestown Massacre were 1960s revivalists, fronted by Anton Newcombe, a charismatic songwriter much given to announcing that he was the harbinger of a musical revolution. Incredibly, it seemed more than standard wannabe rock-star bluster. The Brian Jonestown Massacre were attracting widespread interest from record companies that, you suspect, may have been looking for an American equivalent of Oasis. Indeed, so keen was one major label's talent scout that she set up a special gig at the Viper Room to show the band off to her superiors. Actually signing the deal seemed a mere formality.

Or perhaps not. It is difficult to tell from Timoner's footage exactly when, or indeed why, Newcombe took it upon himself to begin punching and kicking BJM guitarist Matt Hollywood, but it soon escalates into a full-scale onstage brawl. Blood is spilt, bouncers are called in. At one point, a wounded and accusatory voice is heard wailing that his sitar has been broken in the melee. Understandably coming to the conclusion that the Brian Jonestown Massacre may be a little too revolutionary for their own good, the record company executives quietly make for the exit.

The next day, however, Timoner found Newcombe in surprisingly buoyant mood. The fistfight, the lost record deal and even the sorry fate of the sitar appeared to have been forgotten. He announced that he was going to take over the documentary himself. He would introduce Timoner to another nascent band, the Dandy Warhols, based in Oregon, but apparently also part of his ongoing musical revolution. A dumbfounded Timoner agreed: "I was charmed, overwhelmed. I'd never met characters like this before. They were like my fantasies of what bands were like in the 1960s."

Timoner ended up following the two bands for the next seven years, funding her pet project by taking on what she refers to as "professional work": directing videos and TV shows. The resulting film, Dig!, won the Grand Jury Documentary Prize at this year's Sundance Film Festival, and with good reason: at turns gripping, hilarious, painful and almost unbearably harrowing, it is the best film about musicians and the music industry in years.

Guided by their extremely savvy leader Courtney Taylor, the Dandy Warhols ascend to massive success in Europe when their single Bohemian Like You is used in a Vodaphone advert. While their former acolytes perform to vast festival crowds, the Brian Jonestown Massacre slowly reveal themselves to be the most luckless band in history: record deals collapse, tours fold amid drug busts, an attempt at starting a Blur vs Oasis style feud with the Dandy Warhols runs horribly out of control.

The main problem is Newcombe, whose evident mental instability is not helped by a gargantuan heroin habit and an apparently unquenchable desire to attack his fellow band members onstage: the hapless Matt Hollywood finally quits after Newcombe sinks his teeth into his stomach mid-song.

There is a painful moment when the extent of the Brian Jonestown Massacre's failure dawns on Joel Gion, the unflappable percussionist who steals the film with a succession of sardonic asides: "I've just wasted the last four years of my life," he exclaims, "playing the tambourine."

Curiously, given the paucity of entries into this cinematic sub-genre in recent years, Dig! was not the only great rock documentary on show at Sundance this year. Joe Berlinger and Bruce Zinofsky's Metallica: Some Kind of Monster may lack the awful momentum of Dig!, but it is far more entertertaining than a film about multi-millionaire rock stars attempting to make an album while going though psychotherapy (and in the case of singer James Hetfield, rehab) has any right to be.

Unlike Dig!, you suspect the film's humour is largely unwitting: the band's inability to open their mouths without the most appalling psychobabble coming out; the look of total despair on the face of drummer Lars Ulrich's father as his son starts discussing, at considerable length, his "fear of the status quo"; the equally compelling expression sported by the band's "therapist and performance coach" when he is informed that his services are no longer required; the unique logic of a pre-rehab Hetfield explaining why it was necessary for him to miss his son's first birthday in order to go bear-hunting in Russia.

However, the end result is a compelling and ultimately rather cheering portrait of superstardom: whatever you think of the music made by the self-styled "biggest heavy-metal band of all time", you end up both rooting for them and applauding their bravery both for allowing the film to go ahead and not interfering in the production process. "We braced ourselves for notes like, 'I don't like how I look in that scene - cut it' or 'My playing sucks in that scene - cut it'," says Zinofsky. "But there was nothing that they were afraid of."

There are also plenty of other rock documentaries scheduled for release this year, among them Michael Gramaglia and Jim Fields's controversial film End of the Century, about the Ramones, and Mayor of the Sunset Strip, featuring LA scenester Rodney Bingenheimer and a supporting cast that includes everyone from Neil Young to Liam Gallagher. But it might be premature to start talking about a renaissance.

In 2004, the standard rock documentary is not Dig! or Some Kind of Monster, but Tupac: Resurrection, a rotten bit of hip-hop hagiography released this week. Tupac: Resurrection has a vast budget and an impressive stock of rare footage, including diverting film of the self-styled rap "thug" at college, wearing a leotard and performing what looks worryingly like modern ballet to the strains of Kate Bush's Wuthering Heights. However, the film uses these clips to convince the audience that Tupac Shakur was not a convicted sex offender whose marijuana-fuelled paranoia led him to provoke a series of petty arguments that ended in a string of murders - including, possibly, his own - but was in fact the light of the world. The accompanying literature sets the tone of the film by comparing him to Martin Luther King.

Its fatal flaw becomes apparent early in the opening credits. The film is a collaboration between MTV and Amaru Entertainment Inc, the company set up by Shakur's mother and responsible for the unceasing glut of posthumous Tupac CDs and books. It has sacrificed balance and editorial control for access. In doing so, it neatly summarises the problem with most modern rock documentaries.

"They're so hard to make," says Bob Smeaton, a veteran British rock documentary director who has won two Grammys for his work and whose portfolio includes the Beatles' Anthology and episodes of the acclaimed Classic Albums. "It's hard to raise money to make documentaries on rock for television, let alone cinema. People see so much rock music these days, on VH1, MTV, people are inundated with it. You can't go out and say, 'Let's make a documentary about Coldplay', because people who would invest in them turn around and say, 'Well, what's new about that? We see them every minute on TV'."

It seems that the only people willing to finance rock documentaries are record labels, looking not for great film-making or gripping insight, but for a bland, officially authorised promotional tool, preferably tying in with the release of new albums.

At best, the end results are advertorials, so hysterical in their praise of their subject that anyone can see straight through them. That was certainly the case with This Is So Solid, part funded by So Solid Crew's record label Independiente and broadcast on Channel 4 in 2002. It opened with the remarkable premise that So Solid Crew were "the most innovative thing to happen to the music business for the last 30 years", and became progressively less even-handed from then on.

At worst, they are actively misleading, like Right Here, Right Now, the infamous 1997 BBC documentary about Oasis, which featured the Gallaghers touring their native Burnage in a people carrier. It was later revealed that the urban wasteland the brothers appeared to be gazing forlornly upon was in fact not Burnage at all, but footage shot later in nearby Rusholme.

It's no exaggeration to say that entire PR departments exist within record companies with the express purpose of stopping people making films like Dig! and Some Kind of Monster. While the bands in Dig! were unsigned at the time shooting began and therefore had no record company to stop them taking part, Metallica were forced to intervene financially in the making of Some Kind of Monster, buying out their label's interest in the film in order to give control back to the film-makers: "The record company wanted us to finish the film before the story was over, short-circuiting the editing process and denying us the time we needed to make the film we wanted to make," says Berlinger.

"It's completely retarded, isn't it?" agrees Timoner. "I have been hired in my professional capacity to document bands by record companies and then been denied access. They're only hurting themselves. They think 'Ooh no, this is not for the camera', but a film like Dig! is probably the biggest commercial tool a band could ever dream up. The bands featured in it are selling records everywhere the film plays. When it goes to festivals, the record stores sell out."

Bob Smeaton's most recent project involved making a film from footage of the Festival Express, a bizarre 1970 tour of Canada, in which Janis Joplin, the Grateful Dead, Buddy Guy and the Band travelled from stadium to stadium in a specially-commissioned train.

You need a pretty high tolerance level for rambling blues rock "jams" to get through the whole thing, but Festival Express reveals just how much music industry attitudes to documentary making have changed in the past 30 years.

In one remarkable scene, various musicians partake heavily of a vast display bottle of Canadian Club whisky that persons unknown have doctored with LSD. The resultant bug-eyed chaos is hilarious and oddly moving.

"I've always loved you Janis, since the first time I set eyes on you," says The Grateful Dead's Jerry Garcia to Joplin, with a touching, if wobbly sincerity, rendered all the more poignant by the fact that mere months later, Joplin was dead from a heroin overdose. It's a scene that would never be seen today, not because rock musicians have become in any way more puritanical in their habits, but because the minute anyone hoved into view with an LSD-spiked bottle of whisky, a record company PR would appear, waving the filmmaker's contract with the record company and firmly suggesting the cameraman hit the off switch.

"One of the great things about Festival Express is that the guys who filmed it got so much access," says Smeaton. "I've interviewed a lot of big stars - Pink Floyd, Lou Reed, the Beatles - and normally, you're given two hours with them if you're lucky. You've got to go through management, the publicist and all that stuff. In 1970, there was no publicist on that train, there was a bit less vanity. These days, people wouldn't do it without bringing wardrobe and make-up along. At least on Festival Express we knew that no one was going to turn around after seeing the footage and say: 'We don't like how we look in that shot.'"

The irony is that the great, iconic images of rock-related cinema, to which bands who agree to be filmed presumably aspire, come from films where record labels and artists relinquished control to filmmakers: from the sight of Dylan attacking doleful British journalists in DA Pennebaker's Don't Look Back, to the almost tangible misery of the Beatles' recording sessions in Let It Be.

Four decades on, the music industry has changed, but, as Dig!, Some Kind of Monster (and indeed Tupac: Resurrection) prove, the same rules about rock documentaries hold true. It is something that at least one of the stars of Dig! understands. While Anton Newcombe has taken to the internet to complain at what he describes as the film's "Jerry Springer-esque vilification of his nature", Courtney Taylor, who has yet to see the film, is apparently delighted. "He told me, before this film, that we were a successful band who may or may not have been remembered," chuckles Timoner. "Now we're immortal."

· Tupac: The Resurrection is out this week. Festival Express, Metallica: Some Kind of Monster, Dig and Mayor of the Sunset Strip will be released later this year.

The rock docs they didn't want you to see

Eat the Document (filmed 1966)
Bob Dylan's 1966 British tour was a flashpoint in rock history: he had "gone electric", and nightly faced baying mobs of livid folkies. Yet the film of the event - directed by DA Pennebaker, who was responsible for 1965's acclaimed Dylan documentary Don't Look Back - has rarely been seen, thus denying the public the chance to see a drugged-out Dylan attempting to interview John Lennon in the back of a limousine. Dylan is verbally decimated by the unimpressed Beatle, then throws up in the back of the car.

Up Against It (1967, never filmed)
Not a documentary, but one of the great what-ifs of rock-related celluloid. In 1967, the Beatles commissioned a screenplay from playwright Joe Orton, whose script featured transvestitism, murder, adultery and insurrection. He was scheduled to have a meeting about the film the morning he was murdered by his lover Kenneth Halliwell, but it seems unlikely that the film would ever have been made even if Orton had lived. Paul McCartney later confessed the Beatles found Orton's work "a bit gay".

Cocksucker Blues (filmed 1972)
It was Mick Jagger's idea to film the Rolling Stones' 1972 US tour, his enthusiasm undaunted by the fact that the last time the Stones had been filmed, at their 1969 Altamont concert, the cameras had captured the murder of an audience member. However, even Jagger was horrified by Cocksucker Blues: a parade of debauchery that includes Keith Richards nodding out on heroin and telling Jagger about how to snort coke properly, and an orgy in a private plane. Suppressed by the group, the film has gone on to become perhaps the most infamous rock documentary in history.

Live Stiffs Live (filmed 1977)
The 1977 package tour from punk record label Stiff was notable both for the degree of offstage hedonism - in one mysterious incident, a tour manager was hospitalised after being attacked with a glass of milk and a plate of biscuits - and for the rivalry between its joint headlining acts: Elvis Costello and Ian Dury. Both factors ensured that the documentary of the event has never been completed.

Muddy Track (filmed 1987)
"It was fuckin' terrible," said Neil Young of his 1987 European tour, marked by audience riots, a backing band racked by alcoholism, drug abuse and a decline in commercial standing so dramatic that one radio interviewer told Young he thought he was dead. Contrary as ever, Young decided this would be a good time to make a documentary, which he shot himself, only to discover that no distributor would take on a film made up of out-of-focus footage of Young and members of his band rowing. "Muddy Track is not a documentary," he later protested, adding: "I don't know what the fuck it is."