About three minutes into reel No. 2, Adolf Hitler appears on the terrace of his mountain chalet in a white double-breasted jacket and black trousers.

His shoes are shined, and he is wearing a red arm band with a black swastika.

But the swastika is backward, Criss Austin noted as she ran the footage at the National Archives.

After World War II, she said, a piece of original film was mistakenly spliced in backward, resulting in the flawed copy.

It was fixed digitally, she said, and was a crucial step in the National Archives’ project to create the best version to date of the famous home movies shot by Hitler’s girlfriend, Eva Braun.

Now the job is almost done and should be completed this month, said Austin, a film preservation supervisor.

Much of the extraordinary four hours of footage is in color and is known to historians via older copies. The original is missing.

The film features Hitler and top Nazis Heinrich Himmler, Joseph Goebbels, Martin Bormann, Albert Speer and Joachim von Ribbentrop.

But it also captures lesser figures like Hitler’s doctors, Karl Brandt, who was later executed as a war criminal, and Theodor Morell, who treated Hitler with narcotics, amphetamines, leeches, hormones, vitamins and various quack supplements.

Morell also reportedly gave Hitler and Braun the cyanide ampuls with which they committed suicide. Hitler shot himself in the head for good measure, according to historians.

Hitler’s personal photographer, Heinrich Hoffmann, who later wrote a book called “Hitler Was My Friend” and took thousands of pictures of the Nazis, appears in the footage.

So does Reinhard Heydrich, known as “the hangman,” a key architect, along with Himmler, of the slaughter of 6 million European Jews.

The two stand in crisp business suits as they chat on the terrace.

A lot of the film was shot by Braun or her friends at the Berghof, Hitler’s retreat in southeastern Germany, against a backdrop of breathtaking Alpine scenery.

Well-dressed Nazis relax under red beach umbrellas and sun themselves in cushioned lounge chairs.

The atmosphere often seems lighthearted.

At one point, Hitler, in his white jacket and brown military hat, does a little dance on the stone terrace as he talks with another Nazi official. Elsewhere, the fuhrer swats away an insect, and in several scenes, he wears a fuzzy-looking brown fedora.

Later, someone playfully holds what looks like the same hat aloft as if for show. Hitler does not appear to be around. It’s not clear exactly when the footage was shot.

There are plenty of pets – Hitler’s German shepherd, Blondi, and Braun’s Scottie, Bruli – as well as children. At a gathering of youngsters, a little boy of about 5 faces the camera and salutes like a soldier.

People play pingpong. Braun does gymnastic routines.

There are scenes of Easter and Christmas, of Himmler overseeing a wedding and Hitler with the happy couple. (The groom, Braun’s Nazi brother-in-law, Hermann Fegelein, would later be shot as a deserter.)

Meanwhile, about 100 miles away, prisoners were being herded into the Dachau concentration camp, where tens of thousands would be killed, tortured in medical experiments and incinerated in the ovens before the end of the war in 1945.

But up on the mountain, and elsewhere in Braun’s world, life was good.

The film is being updated, the National Archives said, because it is in heavy demand from researchers and needed to be digitized. The National Archives has special negative copies it used for the digital scans, Austin said.

“This is one of the most requested groups of records that we have,” she said. (Most of those asking to see the films are believed to be documentary filmmakers.)

With a suite of high-tech computers, Austin and technicians have been poring over the footage scene by scene, restoring faded colors and removing splotches.

The original 28 reels of film were recovered by the Army at the end of the war.

Allied interrogators learned from former Nazi officer Franz Konrad that he had left the films with his mother in a small town in Austria about 50 miles from the Berghof.

They were found there in October 1945. (Konrad was later hanged for his role in crushing the Jewish uprising in the Warsaw Ghetto in 1943.)

To save space, the Army spliced the 28 reels together into nine, Austin said, and that’s when the swastika error was probably made.

The sequences are not in chronological order.

The National Archives received the footage in 1947.

In 1972, the film was discovered in an storage vault in Maryland by German-born artist and filmmaker Lutz Becker, according to the Guardian newspaper.

It was then woven into the acclaimed British World War II TV documentary “The World at War” in the 1970s, according to the Guardian.

After that, the original film vanished.

It’s not clear when. Investigators found that the last record of the National Archives likely having the original footage was June 1973.

“The whereabouts of the original camera film are in question,” Austin said.

Eva Braun, who was also briefly Hitler’s wife, was 17 when she was introduced to him in 1929 by Hoffmann, who ran a photography business where Braun worked.

Braun was infatuated by Hitler, then 40, fell in love with him and twice tried to kill herself because he wasn’t paying enough attention to her, according to historians.

Although he claimed Germany was his only mistress, Hitler allowed Braun into his inner circle at the Berghof, where she occupied quarters next to his.

The nature of their relationship has long been a matter of debate. Some claim they were lovers. Others reject that. “There never was any love story,” Hoffmann wrote.

Either way, she and her movie camera had intimate access to him and other key Nazis.

In one segment, she appears in the footage standing near Hitler and gestures to whoever is holding the camera to come closer for a better shot.

Some officials seemed to enjoy being before her camera. Others looked wary.

In the section where Himmler talks with Heydrich, Himmler, creator of the Jewish extermination camps, shoots the camera a blank glance.

Goebbels, Hitler’s chief propagandist and stage manager, seems to relish the attention. He bounds up the steps to the Berghof and pauses so the camera can film him being greeted by Hitler’s aides.

Several years later, Goebbels and his wife killed their six children and themselves as the Nazi regime crumbled around them.

But Braun’s films also record simple family vacations and outings.

Her parents and sisters appear, frolicking in a mountain stream, swimming in a lake and riding bikes.

Braun is seen ice skating, picking flowers, cuddling children and pets.

When the war came, and defeat loomed, things changed at the Berghof. Camouflage netting was draped over the house. And a sense of foreboding spread.

When a would-be assassin nearly killed Hitler with a bomb in 1944, he sent his shredded clothing to Braun at the Berghof as a trophy.

After the assassination attempt, Hitler’s mental and physical state rapidly deteriorated.

With disaster closing in, Braun got out her old movies and showed them at the Berghof, according to historian Heike B. Gortemaker.

Goebbels noted in his diary how Hitler had changed from the sunny days on the terrace and was now bent and aged.

Hitler’s final Berghof stay lasted four months and ended in July 1944, according to Gortemaker. The following April, a British air raid smashed the building.

A few weeks before the end, Braun joined Hitler in his Berlin bunker, where they were married early April 29, 1945.

Later on April 29, Hitler tested his poison on his dog, Blondi. It worked.

The next day, he and Braun went into his study, sat on a sofa and killed themselves.