A 40-year-old documentary about Johnny Cash to air on the Public Broadcasting Service shows him in concert and in casual settings. But unlike the 2005 movie "Walk the Line," there's no mention of his well-documented substance abuse.

The documentary "Johnny Cash: The Man, His World, His Music" is expected to air Tuesday as part of the 21st season of PBS' Emmy-winning P.O.V. series.

The documentary was made over several months in 1968 and 1969 when Cash was at the peak of his popularity. He's shown on stage and off: hunting, playfully holding a crow; coaxing his father to sing; signing autographs; posing for photos; and listening attentively to an aspiring singer.

Of course, concert footage shows him opening his show with his famous "Hello, I'm Johnny Cash."

He sings "Ring of Fire," "Great Speckled Bird," "Folsom Prison Blues, "Orange Blossom Special" and, with wife June Carter, "Jackson."

Additionally, Cash and a young Bob Dylan are shown in a studio recording a duet, "One Too Many Mornings."

Director Robert Elfstrom says his portrayal differs from what moviegoers saw in "Walk the Line" starring Joaquin Phoenix for a reason.

"I didn't want to cloud the purity of the story," Elfstrom said in a telephone interview, referring to Cash's drug problems. "I felt it was irrelevant to his art, but the powers that be wanted it in there. I fought it hard, and it was a good decision."

The documentary aired originally on public TV shortly after it was made, was released briefly in theaters, was shown in the United Kingdom and aired last year on the Ovation channel.

Simon Kilmurry, executive director of the P.O.V series, said PBS is airing the 40-year-old show because "Johnny Cash has become an almost mythic figure, and Bob Elfstrom's film captures him as a three-dimensional, complex person at a pivotal point in his life and career."

Elfstrom said he came to regard Cash as authentic.

"Many performers are just performers and you feel a credibility gap," he said. "With John, he was not capable of playing anybody but who he was: A hard-working kid from Dyess, Ark. He was about soul, and he identified with people who struggled."

Cash is shown in concert at the old Tennessee State Penitentiary in Nashville and at Wounded Knee in South Dakota before Indians in their traditional dress.

June Carter Cash, in remarks to the prisoners, calls her husband "old golden throat."

John Rumble, senior historian at the Country Music Hall of Fame and Museum, said in an interview that Cash "had a unique half-speaking, half-singing style. Above everything, he had one of the most memorable voices in all of American musical history. It had the aura of authority but could be tender.

Cash died in 2003, just four months after his wife.

Elfstrom says the documentary captures a special time in the artist's life.

"There are not many documentaries on John, and this was perhaps one of the first and caught him at a point where he had some real peace of mind," Elfstrom said. "He was with June, and whatever bad habits he had he'd put behind him. His career and voice were at the top."

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