FINDING THE PERFECT TEMPO FOR A FILM SCORE
Is there a perfect tempo for a film score? Shouldn’t it be driven by the mood of the particular moment, or the style of the music? Does it even have to be constant?
At first blush, determining the perfect tempo may not seem that important when it comes to film composing. But, while there may not be one perfect tempo, there are a handful that work better than others. Read on to see what factors make one tempo better than another for a film score.
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Traditionally, tempo is marked at the top of your sheet music with some suggestive Italian word or phrase. There’s a certain liberty that can be taken by the performer or conductor. In fact, many metronomes depict a range of BPM (beats per minute) on their settings rather than one precise number.
The mechanical metronomes of the classical composers were notoriously imprecise, even between similar devices. In fact, there’s some controversy surrounding Beethoven’s own tempo markings. If his metronome was mis-calibrated, could he have published his pieces with too-fast tempo indications?
In the digital age, though, we are much more precise. Especially within the environment of a DAW, the speed of a piece of music is computer controlled, and extremely accurate. Therefore, your cue composed at 128 BPM will be played at the exact same speed on your laptop as the studio’s workstation.
This amount of precision makes finding the perfect tempo easier.
BPM vs. FPS to find FPB
What it comes down to is this: how do you convert BPM (beats per minute) to FPS (frames per second) – and why does it matter?
FPS is the speed measurement for motion picture playback. In traditional filmmaking processes, one second of a film is broken up into many discrete frames that play back in rapid succession, thus creating the illusion of movement. If you’ve ever seen a roll of motion picture film, each picture on the strip is shown for a fraction of a second through a projector.
The most common speed for a theatrical film to be shot and delivered is 24 FPS. Broadcast television in the USA and Japan is usually 29.97 FPS, other countries prefer 25 FPS, and some projects may use 23.98 FPS. These are for a variety of technical reasons that you don’t need to know. You should, however ask the editor what frame rate or timebase they are editing in, so you can set your perfect tempo accordingly.
For more weird filmmaking jargon, check out this article.
Now that we know how many frames per second the film will play (let’s assume for this example it’s the standard 24 FPS), we can can do some math to find out exactly what that equates to in seconds. At 24 FPS, one frame lasts 41.667 milliseconds… not immediately useful.
What is more useful is to match the time units between BPM and FPS. We can think of tempo in beats per second instead of beats per minute by dividing by 60. For example, 180 BPM = 3 BPS. Therefore, if you wrote music at 180 BPM (a rather fast cue), then there would be exactly three beats per second of screen time.
Using BPMs in multiples of 60, we can find easily divisible tempi:
- 180 BPM = 3 BPS
- 120 BPM = 2 BPS
- 60 BPM = 1 BPS
Expanding this to half beats (eighth notes in a measure) we get:
- 180 BPM = 3 BPS
- 150 BPM = 2.5 BPS
- 120 BPM = 2 BPS
- 90 BPM = 1.5 BPS
- 60 BPM = 1 BPS
Let the Computer Find the Perfect Tempo
The film composer often has to break down the timing of a cue into accent points (onscreen moments that you want to punctuate with music). In an ideal world, these accents would fall on the downbeat of a measure, at the beginning or end of a natural musical phrase – if only you could find the perfect tempo. However, the real world rarely is that neatly laid out.
There are tools out there that will endeavor to help you find that perfect tempo. Some DAWs such as Digital Performer have this feature built-in (known as the “Find Tempo” plugin). You can set markers at key accent points in the timeline, then DP will suggest a tempo so that each accent falls on or close to a beat. This free online film cue tempo tool does much the same thing, though you have to input your accent points manually.
Let’s Talk Timecode
But let’s not talk too in-depth about it. As a film composer, you should be familiar with the way in which time is usually displayed for video and film. This is called timecode, and it follows globally-accepted standards set by SMPTE. Basically, it shows a moment in a film using this format: HH:MM:SS:FF (Hours:Minutes:Seconds:Frames). Each moment of the film has a unique timecode, and it is a common reference point for talking about specific timings in a film. At 24 frames per second, the counter will start at 00:00:00:00, then advance one frame up through 23 before turning over to 00:00:01:00 and continuing on.
Music software and DAWs have more resolution than video editing software because digital audio files are broken down into samples, rather than frames. Within ProTools or other DAWs, for example, you may see time displayed as Hours:Minutes:Seconds.Milliseconds – but this is not timecode! If you start talking to the director or editor in terms of milliseconds instead of frames, they will look at you funny. Set your time display to SMPTE timecode in your project and don’t look back.
Thinking in Terms of Seconds
An easier way to think about hitting key accent points in a cue is to find a tempo that fits nicely into seconds and minutes. If you work with a tempo that divides well into seconds, then you will know how long each measure will last. Once you get a feel for this, musical phrasing becomes easier because you’ll know intuitively how many bars you have for a particular moment on screen.
In the common case of working within a 24 FPS film and 4/4 time, you can arrive at useful BPMs, such as:
- 240 BPM = 4 BPS = .25 seconds per beat = 1 second per measure
- 160 BPM = 2.6 BPS = .375 seconds per beat = 1.5 seconds per measure
- 120 BPM = 2 BPS = .5 seconds per beat = 2 seconds per measure
- 96 BPM = 1.6 BPS = .624 seconds per beat = 2.5 seconds per measure
- 80 BPM = 1.3 BPS = .75 seconds per beat = 3 seconds per measure
Choosing one of these framerates will let you time out your cue using seconds. For example, if you have a moment to accent at 12 seconds into a cue, and you’re working at 80 BPM in 4/4 time, then the accent will fall on the first beat of the fifth measure. If you have a cue that lasts 1 minute 30 seconds, then you have 30 measures to compose at 80 BPM. This is a very natural method for many composers, and half a second of accuracy (if you’re aiming for the downbeats) is usually adequate for hitting accent points.
Thinking in Terms of Frames
If you can wrap your head around frames per second and frames per beat, then you can start to understand why these conversions are so powerful. Suppose you are writing a cue for a scene that has several accent points. In this case, being frame-accurate can be extremely important. Thinking in terms of “the next accent point is 39 frames away” rather than “the next accent point is about a second and a half away,” lets you figure out precisely how many beats you have until that moment – and exactly how much music you have to write.
Looking back at our initial example chart, we can add in FPB (frames per beat) assuming 24 FPS:
- 180 BPM = 3 BPS = 8 frames per beat
- 160 BPM = 2.6 BPS = 9 frames per beat
- 120 BPM = 2 BPS = 12 frames per beat
- 96 BPM = 1.6 BPS = 15 frames per beat
- 90 BPM = 1.5 BPS = 16 frames per beat
- 80 BPM = 1.3 BPS = 18 frames per beat
- 60 BPM = 1 BPS = 24 frames per beat
This is definitely a more advanced way of thinking about timing your score, and is often the way in which film editors think. You are now in the realm of being truly frame-accurate with your tempo. Your score can hit marks down to a resolution of 4 frames, within reason (if you utilize the eighth notes at 180 BPM).
In practice, this amount of precision is rarely called for when scoring a film. Music editors can slip your cues a few frames one way or another to perfectly match up with onscreen action. They can also imperceptibly speed up and slow down cues, squeezing and stretching them minuscule amounts to fit the picture. So if you are off by just a frame or two, don’t sweat it too much.
The Master Formula for Finding the Perfect Tempo
If you’re curious how I arrived at all of these tempos, or if you’re working outside of 24 FPS and 4/4 time, here is the formula I use:
Take the film’s frames per second (FPS) and divide it by your preferred frames per beat (FPB). Multiply this number by 60 to arrive at your beats per minute (BPM).
Input different variables to solve for FPS, FPB, or BPM. From here you can also find beats per second, seconds per beat, and seconds per measure. Listen to some of your favorite film scores, and find their tempo to see which BPM the composers chose.