Computer Editing: Editing Audio First

Maybe we should blame it on Bruce. Film trivia buffs will tell you that “Bruce” was the affectionate on-set nickname for the mechanical shark that menaced Robert Shaw (and everyone else on or in the water) in the suspense film classic Jaws. Sure, before that film there had been plenty of other movies where the visuals and the sound were so intertwined – but there was just something fundamentally scary about the John Williams “shark music” in Jaws.

After all, the shot wasn’t usually more than a camera pointed at the waves, but with that music, you just knew that there was something terribly menacing just beneath the surface.

It’s a great example of how well planned audio can bring new dimensions to your video. And how, if you give some serious thought to your soundtrack, you can make the sum of the parts even better than the individual elements, alone.

Last month, we looked at some of the editing dynamics when you let the visuals drive the audio in a program. This month, we’ll turn the tables and let our soundtrack drive the visuals. Of course, if you’ve watched MTV or VH1 over the past two decades you’ve seen countless examples of music-driven video.

From the video editor’s perspective, letting the rhythm of a soundtrack drive the editing decisions makes things a lot easier. This is primarily because most music is rhythmic in construction – it has a regular and constant pulse that can serve as a framework for editing.

Chewing up the Downbeat

If you were editing visuals to a standard downbeat-driven rock song, the easiest pattern for your cuts would be to make sure that each one happens on the beat.

With computer editing, this is particularly easy since many packages allow you to display visual representations (waveforms) of your soundtracks. By enabling this display on your timeline, you can actually see the spikes and valleys that correspond to the rhythm of the music you’re using.

When you do that you’ll also notice that major intervals of songs (a four-bar phrase, or a 16-bar theme, for example) are often visually apparent. This makes it a snap to simply place track markers on various musical highlights and slide your video cuts to match. But be cautious of this approach. Don’t forget that variety is one of the elements that makes any program interesting. If you have a four-minute song with a tempo of 120 beats per minute – marking a cut every four beats for 30 equal cut points per minute may not make for the most interesting video. Instead, you can add rhythmic spice to your concoction by varying your edit points.

A long video sequence might require more than a single four-beat measure, if so, there’s certainly no reason you can’t decide to let a scene run past an otherwise natural musical cut point. Or perhaps you want to quicken the pace and cut within the beats, putting four, or even six or more, quick flashes of scenes inside a single musical measure.

The point is that when you use music to drive your visuals, you don’t necessarily need to lock edits to the rhythm to achieve pleasing results. You need to pay attention to how much time your visuals need, and often, that’s not the same as the amount of time that passes conveniently in one phrase of a song.

The Bomb Squad

Another good example of letting your video editing follow the pace of your audio is in the dramatic use of sound effects. Imagine a movie scene where a member of a bomb squad is in the critical last seconds of diffusing an explosive device. It’s the classic scene where the nervous technician is trying to decide whether to snip the red wire or the black one. The soundtrack is of the clock ticking off the final ten seconds to zero hour followed by the jarring sound of the alarm going off.

In the audio track waveform display (Figure 1), you can clearly see the waveforms of tick, tock, tick, tock, tick, tock, tick, tock, tick, tock, RING!

In this sequence, the first shot might use the first two clock ticks (10, nine) to establish the technician’s growingly desperate emotion. The next two (eight, seven) to establish position of the clock’s second hand as it crosses the eight- and seven-second marks. Six might be a quick cut to the wire cutters – hovering uncertainly between red and black. Five brings us back to the technician’s almost panicked face. The next two seconds (four, three) ratchet the tension even higher by showing an extreme CU of the second-hand ticking away his final seconds. Between two and one we re-focus on the technician as he makes his desperate choice, snips the wire and awaits his fate. Then we’re back to the clock as the second hand reaches zero.

Here you insert a brief pause to hold the audience in suspense… Then (RING!) a jarring alarm sound jolts the audience! The final shot in the sequence might be back wide to show our technician sag in relief.

Now take a close look at Figure 2 – as you can see, the actual cuts into and out of the clock hands slightly lead and follow the actual beat as the clock ticks. This is because if you cut right on the beat as the hand is in motion, the audience misses some of the movement. Anticipate the motion at the beginning of the hand sweep and hold it to completion at the end.

Again, the audio is driving the overall pace of the editing, but the actual cuts can either anticipate or lag the actual beats when it’s required to help the audience understand what’s going on.


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The Balancing Act

Maybe the most important point that can be made for each of the styles of cutting we’ve covered in these last two articles – videos where the visuals drive the audio, and videos where the audio drives the visuals – is that it’s important to give time and attention to both in your work.

Many times, getting the visuals right will dictate the audio approach you take. But every experienced editor will tell you that on many, many occasions, it’s something in a soundtrack that sparked an idea for how to best edit a particular sequence.

Help Your Productions Soar

Years ago, I did a video for a local wildlife rescue organization. I’d followed them into the desert where they were going to release a number of rehabilitated owls and hawks back into the wild. I had a scene at sunset where one of the volunteers released a hawk back into the sky, setting it free.

When I was choosing the music for the scene, I noticed that one particular piece of music I was considering had about 15 seconds of light piano intro suddenly joined by a deep bass line. On the timeline, I slipped the music so that the moment of the release of the animal was synchronized with that first big bass note.

When the video was shown at the awards banquet, imagine my surprise when the assembled crowd of 100 volunteers all leapt to their feet and cheered at precisely that point in the video. I knew that they weren’t actually cheering at my video but rather at the return of that animal to it’s rightful place in nature – but I also realized that it was the combination of that musical moment and the imagery on screen together that caused the fantastic reaction.

It’s a lesson that I’ve never forgotten. It’s when video and audio come together that magic starts to happen.

[Sidebar: Pace Yourself]

It’s easy to think about the rhythm of your edits when you’re working on a piece where the video follows the beat of a piece of music. But remember that music isn’t the only production element that has a natural rhythm.

A fast paced sporting event will have a natural rhythm of it’s own. And so will a leisurely pan across the surface of a scenic lake. Good editors notice the rhythm of the events unfolding on the screen and use everything from the number of cuts in a scene to the timing and duration of scene-to-scene transitions in order to support the natural underlying pace of the material.

[Sidebar: Slip it!]

In many musical forms (jazz, in particular), talented musicians often “slip” the rhythm when it suits their creative needs – momentarily anticipating or lagging slightly behind the established beat to add variety to the constant pulse of the music.

The wise video editor can take a lesson from these masters of rate and rhythm and learn to improvise – keeping within the musical structure when it suits the job at hand, and finding new ways to express ideas outside the audio -when your instincts tell you that’s the best approach.

The Videomaker Editors are dedicated to bringing you the information you need to produce and share better video.


  1. I think someone mentioned that it is preferable to place the audio (eg music), first. Seriously folks, its the ONLY way. Discontinuities or mis-matches in the video may be papered-over by a bit of judicious editing. Discontinuities or bad-matches in music are impossible to do anything about. Two examples:-

    There is a local Beach on Dunedin’s coastline called ‘Tunnel Beach’. Initially, in the days before I wrote my own, I tried the exquisite little Scriabin F-minor Piano Concerto’s slow movement, as background. It proved disarmingly simple structurally but, although I love-it-to-bits, the music/video match didn’t ‘do-it’ for me on any level. I trotted out that old Mendelssohn War-horse ‘The Hebrides Overture’. I didn’t like the particular recording, lack of bass, so using my music software I reconstituted the entire piece from the original score, courtesy of a ‘Sibelius’ trial which I never took them up on. It worked like a dream; why wouldn’t it, it is all about the sea, anyway? With the music in place on the timeline, I cut from the best of my shots into the timeline, able to guarantee hairline accuracy of the visuals to the music. Shown at our club, it produced several seconds of silence, before more than one member rose to their feet applauding. With the music in-place it was a breeze to get it right. No manipulation of the music was necessary, except that I cut out some repetitious bits.

    Second example:- A nightmare, which is still a ‘work-in-progress’. Shots taken recently of two New Zealand sealions playing (for want of a better word), in Hoopers Inlet, a local feature. The ‘action’ consisted of them flinging themselves skywards like dolphins, and I mean ‘skywards’ at least body length out of the water in some cases before ‘arcing’ back. These are big critters, and its not just ripples they were leaving on the surface. But, the action was intermittent and unpredictable and could not be depended upon. And, there is the problem, the regular beats and rhythms of conventional music don’t lend themselves to a ‘match’. I have made a start, in that I have marked, in-time, the peak of each leap out of the water, with a single short timpani beat on a bare ‘score’. I am able to locate those visually and audibly as my sequencer allows ‘visuals’ to be run parallel to the developing music.
    But there, I am stuck, until I have a further burst of inspiration. The entire sequence runs for approximately 90 seconds on-screen and was about 70 metres distant from me at the time of filming. The images are OK. I tried croppings and blow-ups of action peaks in ‘Virtualdub’ but there is little variation and the shots have become too pixellated for my liking.

    If real shoe-horning of image/audio together is necessary. the audio too may be tweaked, just a little, by using a DAW and running at slightly above/below ‘speed’ without altering the pitch. I use ‘Reaper’ for that, (and for most of everything else, as well, incidentally, as it is very straightforward to use, which is more than I can say for brands ‘X’ and ‘Y’).

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