Celebrities feature in John Lennon's Imagine interactive music video for UNICEF campaign Katy Perry, Courteney Cox, Idris Elba, and will.i.am among star performers Celebrities take turns to sing a line from the John Lennon classic Imagine Campaign gives millions the chance to record their own versions on an app You even get to place yourself inside the video alongside the A-list singers Every version will form part of a remix by David Guetta for New Year's Eve UNICEF celebrating 25th anniversary of Convention on Rights of the Child Katy Perry, Nicole Scherzinger, Idris Elba, will.i.am and David Guetta are among dozens of stars today launching the biggest sing-along in history - and you're invited to join them. The celebrities feature in an extraordinary music video singing John Lennon's classic Imagine. Taking it in turns to sing lines from the song, they're joined by Courteney Cox, Rumer Willis, Angelique Kidjo, Bollywood star Priyanka Chopra and model Suki Waterhouse. Even UN Secretary-General Ban Ki-moon joins in, accompanied by a choir. Scroll down to watch the video Biggest sing-along in history: The world is being invited to take part in an amazing interactive music video singing the classic Imagine by John Lennon (seen here with Yoko Ono) for a UNICEF campaign Singer Katy Perry (video) also features in the video... as does actor Idris Elba who belts out his line (right) The video spearheads a global campaign by UNICEF to celebrate the 25th anniversary of the Convention on the Rights of the Child. UNICEF was given permission by Yoko Ono to launch #IMAGINE, which offers millions of people the chance to record their own versions of the Lennon classic using an iPhone and iPad app - and you even get to place yourself inside the video alongside the A-listers. Anyone can join in by downloading the TouchCast app from iTunes. Inside the app, they'll see where around the world other people have recorded their versions of Imagine and will be invited to record their own. Using voice activation, the app captures you singing and inserts you into the campaign's launch video alongside John Lennon and the celebrity supporters - it's like a music video selfie. Each version shared will form part of a new remix of Imagine by David Guetta, to be released on iTunes on New Year's Eve 2014. Nicole Scherzinger also features in the video. The video spearheads a global campaign by UNICEF to celebrate the 25th anniversary of the Convention on the Rights of the Child Celebrities including Black Eyed Peas singer will.i.am (above) take it in turns to sing lines from the song Each version shared will form part of a new remix of Imagine by David Guetta (left), to be released on iTunes on New Year's Eve 2014. Pictured (right) is Rumer Willis, the daughter of Bruce Willis and Demi Moore Even if there are 10 million recordings, the DJ says he'll include them all in the unique track. 'I'm really excited to be working with UNICEF on this incredible new project. Our "world" version of Imagine will be like no other - I am proud to be a part of this collaboration,' said Guetta. We have to get the word out that every voice counts and every child counts too. The campaign - believed to be UNICEF's biggest ever global campaign - launches later today with a live performance of the song at the United Nations General Assembly, by all 250 national, regional, and global UNICEF Goodwill Ambassadors, including Hugh Jackman, Yoko Ono, David Guetta and Angelique Kidjo. Commenting on the campaign, Yoko Ono said: 'A dream you dream alone may be a dream, but a dream two people dream together is a reality.' Also among the 56 performers in the campaign video are Craig David, former Voice UK coach Danny O'Donoghue, Sudanese refugee turned supermodel Mari Malek, Australian singer Cody Simpson and actors David Arquette, Eric Christian Olsen, Seth Green, Dianna Agron, and Taye Diggs. Even UN Secretary-General Ban Ki-moon (centre) joins in, accompanied by a choir The video was produced by TouchCast, a New York-based video technology used by the BBC, and Emmy award-winning director Michael Jurkovac, who was behind the viral video sensation Yes We Can in support of Barack Obama's 2008 Presidential campaign. With #IMAGINE, UNICEF hopes to bring awareness to the fact that in many countries, children have to imagine having the basic human rights that allow others of their age to be children. UNICEF hopes to inspire people to take action to fight for global children's rights and raise funds via donations and iTunes royalties from the song's purchase to finance their efforts. Donations will be used to support UNICEF's health, education and sanitation projects in 150 countries. The Convention on the Rights of the Child asked us all to imagine a better world for children - and calls on all of us to make that vision a reality," said UNICEF Executive Director Anthony Lake. The #IMAGINE project gives people across the globe a chance to join a global movement for children, lending their ideas, their visions and, not least, their voices to advance the rights of every child, everywhere. Participants are encouraged to share videos of "Imagine" duets with the hashtags #IMAGINE and #EVERYVOICECOUNTS Click here to visit the #Imagine/Unicef website. To visit the TouchCast website, click here. Regina Wilson - NY Firefighter Angelique Kidjo - Singer Nicole Scherzinger - Singer Cody Simpson - Singer Sigrid Agren - Model Danny O'Donoghue - Singer Roarke - Singer Idris Elba - Actor Kate Naut, Jenny Bapst, Francois Alexander, Samantha Rex - Singers Lance Bass - Singer Dash Mihok - Film/TV actor Priyanka Chopra - Actress/Singer Suki Waterhouse - Model Craig David - Singer Zelda Williams - Actress Joan Sebastian - Singer/Songwriter Adam Lambert - Singer Nasri - Singer Maria Gabriela de Faria - Actress/Singer Ban Ki-Moon - UN Secretary General Professional Performing Arts School Choir Members - School Choir Family School Students - International Students David Guetta - Music Producer/DJ Courteney Cox & Coco Arquette - Actress & daughter Doni & Akai Floyd - Mother & Daughter Mari Malek - DJ Stiletto/Model/Activist David Arquette - Actor Isaiah Mustafa - Actor Scott Foley - Actor Sam Martin - Singer Bianca Yuzon - Singer Justin Bartha and baby Asa - Film/TV actor & daughter Eric Christian Olsen - Actor Antonella Barba - Singer Rumer Willis - Actress Katy Perry - Singer Seth Green - Actor Rebecca Da Costa - Actress/Model Butch Vig - Music Producer Antonique Smith - Actress will.i.am - Musician/Entrepreneur Taye Diggs - Broadway/TV/Film actor Patricia Arquette & Harlow Jane - Actress & daughter Ben Barnes - Actor Rob Kazinsky - Actor Tokio Hotel's Bill Kaulitz - Singer Dianna Agron - Actress/Singer Tony Lake - Executive Director of UNICEF Ore & Neave Segal - Sons of Edo & Ayelet Segal Yuna Kim - Figure Skater Eden Espinosa - Broadway Actress/Singer Sunidhi Chauhan - Singer Nina Dobrev - Actress Julian Morris - Actor Poe - Singer (US) Sanaa Lathan - Actress Amy Brenneman - Actress Trevor Jackson - Singer & Actor