NFL Films producer Steve Trout knew Carson Palmer. Trout directed Hard Knocks in 2009, featuring Palmer and the Bengals.

He also directed the season of All or Nothing with Arizona in 2015. There was a trust there.

Palmer retired in a low-key announcement this past year. During the final seasons of his 15-year NFL career, Palmer vowed he would one day tell his side of the story that led to threatening retirement and ultimately being traded by the Bengals following the 2010 season.

When asked by reporters over the years, he never said when it would be, only that he would at some point.

When Trout pitched Palmer on working together on Palmer’s version of A Football Life, which aired on Friday on NFL Network, he made sure to be clear with the 2003 No. 1 pick of the Bengals.

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“We told him and tell the other folks, too, we have to do this the right way,” Trout said. “We can’t gloss over stuff. We have to hit everything. We told him, everyone is going to want to know. He said, ‘I know, I know.’ I spent three or four days with him in Idaho … and we did three long interviews. In the first one we hit it a little bit but he didn’t go deep enough yet. By the second or third ones he was like, all right, and gave us some of the info we hadn’t heard him say yet. If we hadn’t addressed it I think we would have failed. I think Films would have failed.”

They didn’t in that respect as Palmer opened up in the documentary, airing his take on why his frustration bubbled up so much from the aftermath of the 2005 season to the eventual end in January 2011.

Palmer details signing his mega-contract in 2005 under the impression the team would keep close friend Jon Kitna as his backup.

“They didn’t re-sign him and just disrespected him on his way out the door,” Palmer said to NFL Films. The quarterback goes on about feeling the need for a general manager and to “modernize.”

Then he recollects his confrontation with Mike Brown following the 2010 season.

“Maybe a day or two after the season I called Mr. Brown and said, ‘Hey, can we talk? You have to be aggressive in pursuit of winning,’ ” Palmer said. “I told him how I was feeling. I wasn’t getting the answers I wanted. We get into it again and it’s getting heated. I’m frustrated, I’ve been thinking about all this for a couple years but it’s coming to a boiling point for me and I’m sure the same for him.”

Palmer’s one line about Brown offers the crux of the standoff that left a black eye on his Bengals tenure.

“He’s a very, very, very stubborn man,” Palmer said. “I might be more stubborn than him.”

The rest from there is history. In NFL years, ancient history. Palmer was traded for what turned into Dre Kirkpatrick and Giovani Bernard. The Bengals drafted Andy Dalton and A.J. Green. They made a run to five straight playoff appearances. Heck, they’ve since rebooted the roster a second time since all this went down.

All sides moved on. That’s still the club’s stance. There was no desire to engage the topic from the Bengals front office during the months of production for Palmer’s story. Marvin Lewis, Chad Johnson, Terrell Owens and Frostee Rucker are among the former Bengals interviewed.

The rest of the documentary goes through Palmer’s life and documents a player who preferred to keep his life private and had the undeniable respect of every former teammate interviewed. It also has the clip of Geno Atkins planting Palmer in his return to Cincinnati in 2012.

But Palmer’s side of one of the most controversial turns in franchise history is officially on record.