The Do’s and Don’ts of building a book trailer in the age of AI

Reading Time: 5 minutes

You’ve written the next Star Wars. It feels like that, at least. Your book, the most important thing you’ve accomplished in your life. Written, rewritten, edited and soon to be: launched. It’s only natural for you to expect everyone to be as stoked as you are. It doesn’t matter that audiences don’t line up for books the same way they do for Hollywood. For your story, they will.

Dream on! Because even if that attitude may not necessarily build you that killer box office, put to a good use, your enthusiasm may still generate the same vibe among your fans. With a smaller crowd, but still a crowd.

It worked for me. Being a novelist whose day job is in advertising, it was easy for me to steal Hollywood’s marketing staple and develop trailers to my printed stories.

The first one was ten years ago, when I launched my first book back in Brazil, some friends and I made our first trailer: a 300-inspired, one minute long production, that used fight choreographers, dozens of actors and lots of special effects.

Trailer for Gods of Both Worlds, from 2013:

Since then, I never stopped. For every book I released, I got together with my creative buddies and shot a new cinematic extravaganza to build hype for the title.

That was until this time.

In October of 2024, I’m launching my first novel in English. A year earlier, when I emailed the last draft to my editor, I knew the trailer was next. But The Girl from Wudang is a story about martial arts and artificial intelligence, and around the time I finished it, it was also when the world started to hear about Generative AI — a new form of smart programs capable of concocting surprisingly creative images.

Weeks later, this time in partnership with tech friends instead, we made the first Generative AI book trailer the world would have ever seen.

We were so proud! Yet, there was still one year left for the book launch. Everyone insisted that I hold the trailer and release it closer to the big day instead. But I knew the technology was going to evolve fast, and soon that first trailer was going to look ancient. So we got it out anyway. One year ahead of time, just like Lucas Arts does for their Skywalkers’ saga.

That trailer aged better than I anticipated, I must admit. Mostly because of the advice of the animators. Their visual restraint and commitment to a specific look that wasn’t what everyone was trying with the technology at that time.

Following that video, came a few others. Some turning my visits to China into computerized dreams, some transforming my own martial arts training into elaborate animations, and even a yin-yang-inspired, highly stylized production mixing kung fu choreography filmed in China, computer generated animations produced in Europe and a soundtrack produced by Hollywood musicians here in America.

But then, the technology evolved. In just a few months, generative AI programs became not only more powerful, but also much easier to use. Suddenly anyone with a good eye could use it to execute their vision, straight from their phones.

Three applications in particular have dramatically changed the game.

The first one is called Midjourney, an AI that turns prompts into truly spectacular images — natural language commands, no programing required. There are already masters of prompting out in the world but I would risk saying the program is getting so good, that it’s rare to see it spit out anything that doesn’t look at least very good.

Wudang mountains. (Image by PJ Caldas via Midjourney.)

The second app came later: RunwayML. Runway is like the video version of Midjourney. The results on its prompt to vídeo are improving fast but the function that allows you to upload an image and watch the program turn it into a four seconds video is fascinating. Now we can generate images on Midjourney, let Runway animate them and voila! You have a glimpse of what would be a scene of your book, if it was a movie.

Here’s the above Wudang mountains image, animated by RunwayML:


The third tool isn’t necessarily AI, but it counts as part of the toolset one needs to make a good trailer: the editing app. That field has multiple choices from amateur to professional tools available on the market. If you want to go more high end, I’d recommend Adobe Premiere. If you want to stay casual, try InShot and get everything done on your phone.

Here’s the Wudang mountain animation, edited with InShot:

The trailer above, for example, was made with that trio: Midjourney, RunwayML, InShot. Plus the music from my previous trailers. It took me only an hour from the first prompt to posting in my social channels.

I am not saying any of this to brag. Or to celebrate not needing to rely on others. I am excited with the fact that this little process allows writers with all budgets and skills to get their trailers made too, but that’s not the most exciting part either.

The greatest, most revolutionary value of this technological leap is that authors can now translate what’s in our heads directly into the screen. No intermediaries. No briefing people who will try multiple ideas and still not get it right. This process allows us to download our ideas ourselves. The way a set looks, the way a character dresses, the general mood of the story.

Obviously, I’m not the only one in this adventure. Lots of authors and publishers have been indulging in these new trends too. Some with fascinating results, some not so much.

Happens that having the tools isn’t enough to achieve great creative results. So if I gave you the tips to try ,I should probably share a few common pitfalls to avoid too:

  • Too much explanation — trailers shouldn’t tell stories. They should confuse. They take impressive scenes and show them out of order. Sometimes even mislead on purpose. If you’re trying to tell what the story is about, stop right there and rethink. Trailers are not synopses. They are hype building puzzles.
  • Too much visualization — one of the most magical parts of books is that the “movie” is built in partnership with the reader. Showing too much of who the characters are and how they look like can be a big let down. Showing some is unavoidable, but be careful not to turn that into an excuse to impose your vision onto everyone else.
  • Too many styles and tricks — there are so many features and possibilities we can use… photographic looks, illustrations, typography, editing styles… Most disappointing trailers I’ve seen abuse that freedom and build incoherent visual messes that can be as jarring as a book that changes fonts at every paragraph.

In the end, the craft of a great book trailer is a matter of restraint. Of controlling our impulses to use all the fascinating features we can, our anxiety to share all the details we want readers to know…and make some choices. Pick some — ideas, angles, scenes. Make people curious and move on. Great book trailers are a game of hiding more than showing. It means focusing on the original thought that put us on this process to begin with. The ambition that your book is going to be the next Star Wars, and its new badass trailer is about to drop.


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PJ Caldas is one of the most important Brazilian writers of the 21st century, according to the Dictionary of Literary Biography. He has published four books inspired by the mythology carried to Brazil by the African diaspora, and reached the top five bestselling titles multiple times. Caldas has won an Emmy and is a pioneer in the marketing world having won numerous awards and who sits at the intersection of tech, entertainment and advertising . He is also a martial artist with 40 years of experience in combat sports, including kempo, karate, wing chun, tai chi, boxing and Brazilian jiu jitsu. He currently works in New York City and lives in Connecticut.

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