"The Grateful Dead Movie," now showing at the K-B Cinema, is a lot like a Grateful Dead concert. It is a sprawling, undisciplined and unnecessarily long affair, but the dogged determination and shaggy charm of the performers means that the mess is at least a likable one.

Since Jerry Garcia, lead guitarist for the San Francisco-based band with one of the most devoted followings in pop music, directed "The Grateful Dead Movie," it's hardly surprising that the film has much the same character as the group's music. It was in fact, planned that way: Filmed at a series of concerts the Dead gave at Winterland Auditorium in 1974, the movie is billed as a "concert experience."

But in addition to performances of over a dozen Dead songs, glimpses of the scene backstage and the obligatory crowd shots, "The Grateful Dead Movie" includes some wonderful animated sequences starring the "death's head Uncle Sam" that is the group's logo. Artist Gary Gutierrez gets the skeleton mascot involved first in a game of cosmic pinball and then is a motorcycle joyride - a flashy and strongly visual opening for a film that's concerned mostly with sound.

Garcia says the movie is a "metaphor" for a Dead concert, and with their budget of just under $1 million, he and the various technicians who filmed and recorded the Winterland shows have done their best to give viewer the feeling of being in the front row at a Dead concert. There are close-ups galore, especially during vocals and guitar solos, and the sound reproduction is unusually clear.

But at 140 minutes, which makes it less than half as long as as a typical Dead performance, the film would benefit from more judicious editing. There are too many draggy ballads, especially in the second half , and hardly any of the up-tempo rock standards, such as "Not Fade Away," that are usually requested by "Dead Heads," as devoted fans of the group are called.

The "Dead Heads" themselves are quite prominent in the film, often in funny and revealing segments. They play imaginary guitars, mouth the lyrics to song they know by heart, wait patiently in line for tickets, share drugs with each other demand "royalties" for appearing on film, and try various schemes to get backstage where their heroes are.

But the cameras don't show much about the Dead themselves. Though Jerry Garcia at one point talks about how in a fit of anger "when I was younger" he once threw bass-player Phil Lesh down a flight of stairs, not a word is heard from pianist Keith Godchaux or his wife Donna, one of the group's singers. And Ron "Pigpen" McKernan, the keyboard player and prodigious user of stimulants who died several years ago, si shown in still photographs but other wide never mentioned.

These are flaws typical of movies made by rock groups, but they are less glaring in "The Grateful Dead Movie" than in comparable concert films by Yes, Pink Floyd, Emerson, Lake and Palmer or in "The Song Remains the Same," the Led Zeppelin "rockumentary" that passed through town recently. This is a warm, gentle evocation of The Grateful Dead's music and lifestyle, and there's something interesting in it both for "Dead Heads" and those who wouldn't know a toke from a riff.