The big tease of trailers

As the summer blockbusters hit box offices near you, David Crookes gets the inside track on the industry that can make or break a movie in minutes

Early trailers for The Adventures of Tintin had fans chewing their nails in nervous frustration

We're in the middle of another summer of blockbuster movies. But despite the success of the tissue-waving finale of Harry Potter and the pleasingly non-jingoistic exploits of Captain America it's been an uninspiring slate typified by Michael Bay's woeful Transformers: Dark of The Moon. Jeffrey Katzenberg, a founder of DreamWorks, even referred to the past seven or eight months as "the worst line-up in five years".

It's no wonder then that filmgoers are turning to teaser trailers for 2012's hoped-for megahits, including The Amazing Spider-Man, Judge Dredd's comeback in Dredd and Christopher Nolan's third and final Batman film, The Dark Knight Rises.

"Teaser trailers can be launched a year ahead of release," explains London-based publicist Rupert Fowler. "Nearer to release there can be as many as five different versions, varying in length and concentrating on specific characters or themes."

A major part of a movie's marketing drive, trailers can ensnare: The Tree of Life trailer is a visual treat hinting at intense character-led drama but does little to prepare viewers for the sparse dialogue and 20-minute evolutionary montage. They can tell you little but be slick, dramatic and enticing: the US version of The Girl with the Dragon Tattoo has no dialogue or voiceover and is simply cut to the rapid beats of Trent Reznor and Karen O's cover of Led Zeppelin's Immigrant Song. They can also be poor. Early The Adventures of Tintin trailers had fans chewing their nails in nervous frustration until later ones eased the character out of the shadows and laid on the action.

Above all, they are crucial to get right. "A poorly received trailer can result in much money spent and many hours fretted working to turn opinion around ahead of release," says Fowler.

Trailers came into being in 1913 when the Loews Cinemas company created one for the Broadway musical The Pleasure Seekers. The early offerings were usually cringe-worthy and audiences knew they were being sold something. The Bishop's Wife , in 1947, gave a nod to such tactics with a self-referencing trailer that had David Niven and Cary Grant on their way to film a promo for the movie.

Until the 1950s, American trailers were produced by the National Screen Service, although some directors such as Alfred Hitchcock and John Ford liked to produce their own. In the 1960s film directors took a keener interest, leading to more stylish trailers. Plot spoilers in trailers still existed into the 1970s – the three-minute trail for Speilberg's shark fest Jaws showed so much footage and dialogue it was akin to an abridged version of the film.

Today, producers understand they are not selling a narrative but an abstract representation of one. They tend to make films seem like an offering ("the producers of Film X bring you...") and they stick to strict time limits of two minutes and 30 seconds as laid down by the Motion Picture Association of America.

"Fractions of a second make all the difference in whether a joke 'lands' or doesn't or whether a montage builds to the right climax or whether a drama trailer just plays," says trailer editor Mark Woollen, who has worked on promos for The Tree of Life, True Grit, The Social Network and Black Swan.

Editors work to a script that reflects the direction and style of the overall campaign. Sometimes they are given raw footage and wade through dozens of hours of film, attempting to boil it down to about 2,880 frames.

Great trailers are always about raising questions but never answering them, and about whetting your appetite," says Woollen. "Music is everything." It's rare a film's actual score will appear in a trailer since the movie is rarely finished by the time the trailer is edited. Many use music from other movies or pre-recorded tunes with regular beats and rhythms.

"Trailer companies also use music supervisors who review music and provide it to producers and editors," says David Malki, who has edited trailers for Michael Moore's Uprising and Thank You for Smoking. "This can include bands and labels that want their songs featured."

And let us not forget the voiceover. It's nearly always a man. But why? "I think it's a matter of tradition," says Malki. "A male voice brings a sense of authority and gravitas. I don't know what this implies about us culturally. TV adverts are much more egalitarian."

"I prefer to have the movie's characters and dialogue tell the story," says Woollen. "A couple of strong lines of dialogue or voiceover from a character can really set-up the premise. Then the visuals can be impressionistic and convey the rest."

Another trick is the montage: the 20- frame smile, the split-second head turn or blip of light as a character moves. Trailer editors look for iconic, easily read images that have strong emotional impact and stick in the memory. Fast cuts make even the most turgid of movies appear exciting, although some horror or comedy works better with tension and timing.

Some trailers can be better than the films. "George Lucas' Star Wars prequels were lousy but the trailers were incredibly stylish and expressive," says Daniel Hesford, who is writing a thesis on the subject. "They used minimal percussive soundtracks, musical cues from the famous score, skilful montages and the best, most expressive and aesthetically spectacular shots from the films themselves."

The Golden Trailer Awards were set up 12 years ago by sisters Monica Brady and Evelyn Brady-Watters. "When you add up all the numbers, it's close to a $200 million industry when it comes to cost of making these trailers," says Brady. "It's a big industry driving an even bigger one."

In the future, trailers will become more engaging. Not content with eye-catching mini-movies attracting the hits on YouTube, studios want interactivity. Woollen owns i-Trailers, which produces trailers that let viewers discover more information and behind-the-scenes footage. He says. "A good trailer is all about seduction. It should tease you, make a strong impression, and then leave you wanting more."