Question: When did filming of the music video 'Wide awake' begin?
About the article "Wide Awake (Katy Perry song)", section "Background".

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  Drake (featuring Rihanna) — "Take Care"  Gotye (featuring Kimbra) — "Somebody That I Used to Know"  M.I.A.
— "Bad Girls"  Katy Perry — "Wide Awake"  
Music video.
In March 2012, during an interview with MTV, Perry stated: "I know exactly what that music video is.
I know exactly who is directing it.
I know the art direction, the people, the narrative, and I had that idea while I was writing the song".
Filming of the official 3D music video for "Wide Awake" began on April 30, 2012 and ended on May 2, 2012.
The music video was directed by Tony T. Datis and will be used as a tie-in promotion for her 2012 3D autobiographical documentary film, "", as part of her deal with Pepsi.
On June 12, 2012, an official trailer directed by Lance Drake, was released on Perry's VEVO channel.
It started with a girl flipping through a book which displays flashbacks of the "Teenage Dream" era, describing each of the singles as a 'chapter', with Wide Awake being 'the final chapter'.
It also unveiled that there will be a fairytale storyline, with 'a giant labyrinth, a poisoned strawberry, a curious cat, prince charming, and a little girl'.
A second preview aired on June 13, 2012 during the season finale of the program "Randy Jackson Presents: America's Best Dance Crew".
  "Dreaming Wide Awake: The Music of Scott Alan" (2007) as featured soloist on the track "Now"  
Filming for the "Sweet Spot" music video was slated to begin filming in July 2012.
On June 27, 2012, a lyric video for the song was uploaded to Flo Rida's Youtube channel.
It included "bubble gum, lollipops, ice cream, and tasty looking women all through a fisheye lens".
However, no news on the video arrived until January 2013, when it was revealed that the music video was in production, with Ethan Lader serving as director. 
Perry debuted the song in an acrobatic fashion for the first time during the 2012 Billboard Music Awards on May 20, 2012, where she floated over the stage in a white ribbon swing keeping her suspended in the air while several background dancers performed with aerial silk.
On June 17, 2012, Perry performed "Wide Awake" at 2012 MuchMusic Video Awards, in which she stood on a raised platform, beginning the song as a cocoon and turned into a butterfly when she sang the last chorus.
On June 26, Katy Perry performed "Wide Awake" on "Jimmy Kimmel Live!".
Instead of taking the Kimmel stage, she performed a medley of her hits including "Wide Awake" into her "Part of Me" premiere in Hollywood Boulevard in Los Angeles.
For President Barack Obama's 2012 presidential candidacy, Perry performed several of her hit songs dressed as a ballot, including "Teenage Dream", "Firework", and "Wide Awake".
Expressing solidarity for his campaign, the box next to Obama's name was shaded.
American singer-songwriter Kelly Clarkson played an acoustic rendition of "Wide Awake" at a concert in Concord, California which was held on July 25, 2013 as part of the singer's 2012 Summer Tour.
Throughout her performance, she included "delicate" falsettos and "signature riffs".
A cover version of "Wide Awake" is on the track listing for the compilation album "Kidz Bop 23" (2013) by Kidz Bop.
The song was also covered by Jake Puckerman (Jacob Artist), Kitty Wilde (Becca Tobin), Tina Cohen-Chang (Jenna Ushkowitz), and Wade "Unique" Adams (Alex Newell) in the 2013 "Glee" episode "A Katy or a Gaga".