NEW YORK -- Taylor Swift is releasing a live concert special from her star-studded "1989 World Tour" exclusively on Apple Music.

The pop star announced Sunday, on her 26th birthday, that she will release the "The 1989 World Tour LIVE" on the streaming platform on Dec. 20. It will not be available for purchase, but it is free for streaming for Apple Music users.

The concert, directed by Jonas Akerlund, features Swift's performance in Sydney, Australia, at the ANZ Stadium, taped on Nov. 28. It will also include appearances from the many celebrities and musicians who surprised fans on the tour, from Justin Timberlake to Mick Jagger to Kobe Bryant.

Apple Music is currently the only streaming platform where Swift's bestselling "1989" album is available. Swift, who wrote a critical Tumblr post in June about Apple's initial decision to not pay artists during its free, three-month trial launch of Apple Music, said Apple contacted her about capturing one of her concerts for a special.

"I think I'd be leaving a huge part out if I didn't mention the blog post that I wrote . I think that is probably the starting point because I didn't have a personal relationship with Apple until that point," Swift said in an interview with Zane Lowe of Apple Music's Beats 1 Radio (the interview airs Monday at noon Eastern). "I'm sure there are better ways to introduce yourself than to say, 'This is what I'm upset about, please think about our industry.' It got more attention than I thought it would because I'd been echoing those sentiments for years."

Apple changed its decision to pay artists, but Swift said she was a bit terrified after posting the letter.

"And then I was struck with this overwhelming sense of fear. Like, are they going to turn my phone off? Are they going to turn the video camera on? Are they watching me right now? Am I going to wake up tomorrow and all of my music will be off of iTunes?" she said. "Like absolute terror hit."

She added Apple "had shown such humility in what they did . so that's how we get to (here)."

Swift's stadium tour featured a number of her hits songs, including every track from "1989," which has sold more than 5 million units and earned her seven Grammy nominations, including album of the year.

In the special, she performs in front of 76,000 fans.

"There's kind of a switch that flips as soon as I hear lots of people screaming, and that's how I'm programmed. Like people start screaming and it makes me rise to that, it makes me rise to their level of excitement, and that's just how it's been this tour," she said. "Maybe it's because I love playing this record."

Other musicians who popped up on Swift's top-grossing tour include Lorde, the Weeknd, Alison Krauss, Fetty Wap, Steven Tyler and Miranda Lambert. Celebrities who made appearances ranged from actors to athletes to models, including Ellen DeGeneres, Serena Williams, Lena Dunham, Kendall Jenner, Julia Roberts, Chris Rock and the U.S. women's soccer team.

"It happens different ways different times," she said of the guests. "I hadn't met Fetty Wap before but love him, so we'd reach out and go, 'Here are the dates we have' . but then there were people like my friend Selena (Gomez) or Lorde or whatever -- I'd just text them."