Music made specifically to be licensed for use in trailers is a HUGE industry. Just in the last decade, the number of companies making epic trailer music has really exploded. This 2015 Variety article lists a lot of the biggest ones, but if my LinkedIn connection requests are any indication, there are A LOT of composers out there looking to get in.
The reasons for using trailer production music is two-fold. First is that it's MUCH cheaper than licensing something from a feature film or popular music artist. A production music license could be a few hundred to a few thousand dollars, whereas something more well known can EASILY get into the multiple tens of thousands of dollars (which is another reason there are so many music covers in trailers nowadays)
The second reason a company might want to use production trailer music is that it's typically designed so that an entire trailer can be made using only one cue. Because of this, listening to trailer production music is a great way to help a beginner understand typical trailer structure.
Here's a cue made by Audiomachine which is a very typical epic movie trailer score.
Here's what the cue looks like after I've put it through my marking system.
You can see that there aren't a lot of green markers; I use those to indicate when the music is repeating a motif. This music is designed to build up to a climax, and then live in it for a little while to let the trailer do its thing as it shows off all the epic shots.
Here's how I'd describe the structure of this music cue:
Slow introduction gradually ramping up intensity
Build to a new medium intensity
Build to a higher intensity
Build to EPIC intensity
Fakeout moment of silence
Final finish to main title
Slow lead out for additional credits
This parody video you might've seen about trailers understands this formula to a T.
If you listen to a lot of trailer music you'll find that darn near all of it has this structure. It might be cliché, but it still works.
This music is fantastic for beginner trailer editors because it has all the parts you typically need in roughly the exact lengths you might need. Even if it's too long, it's made to be easy to edit. When I edit fan trailers I mix up multiple cues because I almost never find one that can accommodate each section of my trailer.
I wish I had access to this sort of music when I first started learning to edit trailers. It's much much harder to blend together different music cues into one cohesive trailer. If I had this sort of music as a beginner it wouldn't have taken me so long to figure out what it is I needed to make something that sounded like a dynamic trailer.
So if you're just starting out learning how to edit trailers, listen to trailer music like this, and pay attention to its structure. Then go and watch some movie trailers and see how the motifs are used in conjunction with dialogue and sound effects. Eventually you'll develop an ear for the music you need to edit with.
Whenever I talk about trailer structure I worry that I've just found this one formula that works, and I'll never ever make a trailer that's original in any way. I'm always trying my best to do something that feels unique, but ultimately I still go with what feels good. Even if the trailer turns out well I always have the nagging feeling that I could've done something better.
Through writing this newsletter I've often found myself thinking: "I'll talk about this unique trailer, because it totally breaks trailer editing conventions!" then as I write the article about that trailer I just end up finding a way that it still adheres to the same basic formula, even if its music or sound structure is unique in execution.
My hope is that by doing more work, I'll be less inclined to do something with too similar an execution as a previous trailer, and that I'll naturally gravitate towards new ideas. That said, I still REALLY LIKE typical trailer structure; it's very satisfying and entertaining to watch. The other thing that keeps me from going crazy is knowing that even if there are similar repetitions of structure in my work, I'm still working on totally different games and stories, so that alone will be what makes each piece unique.
Note: If you're planning on making fan trailers and uploading them to YouTube, trailer music production houses typically don't care as long as you're not using it for commercial use without permission. I've frequently seen official comments on official Facebook page to stop inundating them with requests for permission. That said, there are some companies like Audiomachine that have very flexible licensing terms and pricing structure.
So do your own research and be respectful of the hard work these composers put into this music. Writing: "NO COPYRIGHT INTENDED, I DON'T OWN ANYTHING" in your YouTube video's description doesn't legally mean anything at all. All it says is that you have no clue how copyright law works. Even if something gets flagged on YouTube, the experience you gained is still worth it, and you can still share it the old fashioned way by showing a person what you made face to face.