Clocking in at a staggering four hours, Bob Dylan: 1975-1981 Rolling Thunder and the Gospel Years is not out to convert the unconverted. Let's be clear: This unauthorized biography is for, and only for, the diehard Bob Dylan aficionado. Causal fans and non-stalkers need not apply. If your knowledge of Dylan is limited to, say, his most popular songs or a handful of albums, you had best be on your way.

The documentary features seemingly unedited interviews conducted by Joel Gilbert, lead singer of Highway 61 Revisited, which purports to be the world's only Dylan tribute band. With a painstaking thoroughness usually left for forensics crime investigators, Gilbert questions an array of music biz types -- singers, studio musicians, record producers, critics, etc. -- about Bob Dylan's career from 1975 to 1981, a period in which he went from the ballyhooed Rolling Thunder concert tour to born-again Christianity.

We start with a lengthy interview with Rubin "Hurricane" Carter, the wrongly incarcerated prizefighter whose plight was taken up by Dylan and immortalized in his 1976 protest anthem, "Hurricane." Carter, once convicted for a murder he did not commit, has an obviously compelling story to tell, but the filmmakers let it drone on into minutia about his appeals process. From this inauspicious beginning, Gilbert transitions into the Rolling Thunder Revue, in which Dylan spearheaded a carnival-like tour extravaganza that also featured such stars as Joan Baez, Ramblin' Jack Elliott and Joni Mitchell.

Finally, Rolling Thunder and the Gospel Years wraps up with an interminable section on Dylan's years-long flirtation with fundamentalist Christianity. Gilbert actually devotes a good deal of time quizzing his interviewees about Christianity, gospel music and the Book of Revelation.

Exhaustive and exhausting, Rolling Thunder and the Gospel Years is an obvious labor of love. And like the Good Book says, love is patient. A great deal of patience is required for a Dylan documentary that contains no Dylan songs and utilizes only minimal footage of the folk-rock icon.

In a valiant attempt to lend a bit of artfulness to the proceedings, the moviemakers toss in quickie images of words and phrases that an interviewee happens to mention. For instance, when record producer Jerry Wexler jokingly calls himself "a card-carrying Jewish atheist," the viewer is treated to a mock identification-card reading "Jewish atheist." When Hurricane Carter quips that "even a cockroach has a right to protect himself," we get an illustration of -- you guessed it -- a cockroach wearing boxing gloves.

Somewhere in Rolling Thunder and the Gospel Years, a Dylan acolyte recalls the critical drubbing that Dylan took for the four-hour Renaldo and Clara, the singer's self-indulgent experiment flick of 1978. The acolyte suggests that one's appreciation of that universally panned movie was directly proportionate to one's reverence for Bob Dylan.

The same might be said for this work, too. I consider myself a Dylan fan. I own a dozen of his records. I've seen him in concert a handful of times. And I found this documentary to be almost excruciating.

Video:

An unexceptional, sometimes amateurish, video production, don't expect to be wowed. Heck, a tripod and camera appear behind a handful of interview subjects.

The 2.0 Stereo audio is fine for the nonstop parade of interviews. A more ambitious sound would have been nice, but considering that this is a music-free documentary about a musician, the rote audio seems par for the course.

Journey to Hibbing is an 11-minute travelogue in which Gilbert visits Dylan's birthplace of Hibbing, Minnesota. We see a bit of Dylan's childhood home and the local high school, and Gilbert visits with a resident who played drums for Bobbby Zimmerman's high school band. The featurette actually helps us warm up a bit to Joel Gilbert, as we glimpse a bit of his dry sense of humor.

Ramblin' Jack's Early Days is a 13-minute interview with folk legend Ramblin' Jack Elliott, who reminisces about his musical beginnings and his earliest experiences with Woody Guthrie and Bob Dylan.

Photo Gallery 1975-1981 is a collection of still photos, most of which also show up in the main feature.

Soundtrack provides a brief sampling of three background songs employed in the documentary.

The endurance contest that is Rolling Thunder and the Gospel Years dictates that I not recommend it for rental or purchase, and yet those who worship at the shrine of Dylan are bound to find segments of the film interesting. There really is a decent documentary buried in here somewhere. Some judicious editing could have uncovered it.