Ben Zecker picks up his baton as the chatter from the orchestra quiets down. A voice in his earpiece says they’re ready to go. The lights dim in the wood-paneled soundstage and, on a large screen behind the musicians, a clip from “Dawn of the Planet of the Apes” is projected. Zecker counts out loud to establish a beat, waves his baton and the musicians begin playing, perfectly in synch with the action seen onscreen. The music they’re playing isn’t the original score, but rather music written by Zecker over the previous three weeks.

He is one of 12 composers selected internationally for the American Society of Composers, Authors and Publishers Television and Film Scoring Workshop with Richard Bellis. Each year, ASCAP selects 12 applicants from around the world to spend a month in Los Angeles, scoring their own music for a clip, listening to lectures from top-tier composers and learning how the business works.

Zecker, who graduated from New York City’s the New School in 2004 after studying composition and performance, says the program “basically plug(s) you into the whole Hollywood experience. You meet music editors, the score mixers, composers, orchestrators somebody from every part of the team.”

The workshop, started in 1988, is headed by composer Richard Bellis, a member of the ASCAP board of directors who acts as host and mentor alongside ASCAP’s Michael Todd and Jennifer Harmon. Bellis has scored more than 45 films and television movies and received an Emmy for his work on Stephen King’s “It.”

“You cannot pay to be a part of this program,” Bellis says. “Every year we get submissions from approximately 300 people internationally, and 20-some professional judges are the first round of adjudicating the people. So by the time we pick the final 12, every year we have the best that the world has to offer in the way of potential.”

The program’s alumni network runs the gamut of current TV and film scoring: “Straight Outta Compton,” “Bones” and the “Insidious” franchise were all scored by composers who were selected by ASCAP.

This year’s group consists of composers from China, Russia, Ireland, England, Spain, Colombia, Germany and the U.S. Each applicant sent in three samples of work, a resume and a biography. After the judges narrow the list down to 60, the top 12 are selected by Bellis, Harmon and Todd.

The composers arrived on July 13. On their second night, each one drew out of a hat to see which of three scenes they would be assigned: “Rango,” “How to Train Your Dragon 2” or “Dawn of the Planet of the Apes.” They were encouraged not to listen to the score that was originally written for the movie and were only supplied a scene with dialogue and sound effects.

Stefan French, who was selected for the program from Ireland, is a Dublin-based master’s student in film scoring at Pulse College. French says when thinking creatively about how the music should sound, he breaks it down emotionally.

“What is it saying and then in turn, what do you want to transmit?” French explains. “So it’s really trying to cut into the core emotion in the scene.”

French’s scene from “Dawn of the Planet of the Apes” shows Jason Clarke’s character having a moment with Caesar, an ape played by Andy Serkis.

French and Zecker both drew this scene for their composition.

“That was a tough scene because there’s no dialogue and it’s very slow-moving and emotional and it’s very drawn out in a way, which is very effective, so there’s a lot of ways to go wrong,” Zecker says, laughing. “I just tried to really adapt to the picture and extract what was important and get the feeling of what was happening without over-writing.”

After selecting the scenes, the 12 composers meet with various professionals to learn what the limitations of their composition could be. Music editors teach them what a music editor does and principal players from the orchestra — from the lead clarinet to a percussionist — explain how advanced the composition is allowed to be.

The second week is about inspiration. The group meets with John Powell, who most recently created the score for “Pan.” Powell walks them through the non-musical side of composing, from connecting with the director to thinking about how the music can best fit with the emotion of the movie.

Throughout all this, the composers spend time writing the music. By the end of the third week, their three-minute piece is due. Professional orchestrators analyze the score and offer small tweaks, such as raising a section by an octave or cutting back on the volume.

The final week is when it all comes together. The composers meet at a soundstage on the 20th Century Fox Studio lot. Each one gets 16 minutes in front of a 60-piece studio orchestra, the same caliber ensemble used by Hans Zimmer or James Horner. Their music is recorded and, by the end of the week, it is dubbed into the scene with dialogue and sound effects.

Also during this time, the group gets to tour Hans Zimmer’s studio. Finally, they work with composer Bear McCreary at the ASCAP office in Hollywood. McCreary, who has scored for “The Walking Dead” and “Agents of SHIELD,” tells them they should relate to directors as storytellers first and musicians second.

“The relationships that were working for me were the ones where I was relating to my clients as filmmakers. I would come in and talk about nothing but story, talk about character, talk about anything other than music,” he said. “You get them talking about their movie or their film and things start to reveal themselves about what they’re insecure about, what they’re secure about.”

McCreary showed a clip of BBC’s “Da Vinci’s Demons,” which he scored, without music. He then questioned the group step-by-step on the emotion each shot was meant to portray. After doing it once through without discussing music, they repeated the process and discussed how the music could depict those emotions.

For many of this year’s composers, the ASCAP session is only the first step. Zecker will move from Boston to L.A. in September, packing up his car and hoping that he’ll get to stand in front of countless more orchestras, adding one more layer to the magic of moviemaking.

On the final day of the workshop, Bellis, along with other professional composers, critiques the outcome and offers advice. He says it’s as much about imparting wisdom as it is about analyzing the work.

“This should always have lessons,” Bellis says. “It shouldn’t be, ‘I spent a month but I got a great demo out of it.'”