Be heard when flying your drone! How-To

When I first received my Spark, I couldn’t wait to go and get flying, so when I finally did (as described here) around Marina Barrage, I hadn’t yet had enough time to go through the entire manual, and read up on some of the finer points of drone-flying.

Thus, when reviewing my first flight’s footage what astonished me (apart from the beautiful scenery) was the fact that there was absolutely no audio – zero. First I played with my phone’s volume buttons, then tried with headphones, then I finally googled it. As common sense might suggest, flying a drone makes a lot of noise, and putting a microphone in the drone (while not impossible) is highly unlikely to produce any kind of usable soundtrack.

Many people (me included) try to overcome this issue in more or less artistic fashion by selecting suitable music (according to mood, time of day, speed of cuts, etc. – I use Audioblocks) and aligning it during editing. This makes for good video – after all, who wants to watch a 2-3 minute video with absolutely no sound? When the latest Star Wars movie came out, people were surprised about a scene with absolutely no sound. Actually, some cinemas put up posters warning moviegoers that it’s not the sound system failing, but actually intended to be way it is.

Now, putting (hopefully) beautiful music over a drone video is all nice and good, but sometimes you might find yourself flying in an awesome location, be it in nature or in the city, where the soundscape makes up part of the places atmosphere (you can imagine “city sounds” or “birds chirping“). Wouldn’t it be awesome to capture that along with your footage from a hundred meters above?

Turns out, there are several ways, so let’s look into them:

  1. Use stock audio from either a paid or free site (I use Audioblocks, but there are many others) – choose which mood you’re looking for and download an appropriate sized bit of audio.
  2. Record separate audio with your phone later on (e.g. put your phone on the ground and shoot a two minute video of which you’re only going to use the sound) – this can work and capture the atmosphere of your current position (I’ve done so in this video), however, it may not be in the exact place you’re flying or it may be a few minutes/hours later.
  3. Use the DJI Go4 app to record audio as you fly (capture the video from the video cache later on instead of just downloading the video from your drone’s SD card) – you could try this, however, audio quality is likely to be impacted as the controller wraps around your devices microphones, and it may even capture sounds like you grabbing your controller or similar.
  4. Use a separate audio recording device – this is what I’m going to be talking about in this post!

Wanting to capture audio whenever flying my drone, enhancing my flight experience (and hopefully your enjoyment when watching my videos), I researched a bit and got an entry level sound recorder from Sony (UX560F to be exact). Although there are options which are more expensive that would presumably record better audio, what I was looking for was: Portability (it should fit in my standard DJI drone bag), Battery Life (I don’t want to worry about recharging it as often as my drone/controller), Recording to a MicroSD card (so I can use the same interface that I use to transfer my drone video and GoPro video).

Yesterday, I had the chance to take my Spark and my new audio recorder with me for a quick test flight around Bishan Ang Mo Kio Park. After a bit of editing, this is what I came up with:

If you like this video, read on for the…

…How-to & Making-of

Step 1 – Record Audio

Obviously, you’ll have to get your raw data from somewhere, so it’s best to pack up all your drone stuff and bring your shiny new audio recorder. Pick a good place to fly and get ready (I’ll assume you have your own pre-flight checklist all set up). Since the audio recorder’s battery is likely less of a critical issue, you should go ahead and power it on, then switch on your drone and wait for it to connect to the controller and for the video feed to show on your mobile device. At that point, hit the record button on your audio recorder first, then start recording video on your drone (but don’t start up the propellers yet).

The most important part is: with your recording started, clap your hands 3 times where the camera can see and the audio can be heard. You’ll need this later on for synchronisation purposes!

Once that’s done, go ahead and start up your propellers and fly normally. If you brought multiple batteries, you’ll want to stop/start your audio each time to make sure your audio is saved in separate files just like your video will be. For each battery, repeat Step 1 until you’re certain you’ve got enough footage (or run out of batteries).

Step 2 – Transfer to your computer & import to your video editor

Once you’re done with recording, collect the Micro SD card from both your aircraft and your sound recorder and transfer the files to your computer. If it’s helpful for you, you may want to go ahead and rename the files accordingly to match (e.g. video-1, audio-1, video-2, audio-2, etc.).

Then, go ahead and import everything to your preferred video editing suite. I’m using iMovie on MacOS at the moment (and thinking about upgrading to Final Cut Pro X), but I’m sure there are equivalent and/or better solutions out there – the point being, you’ll most likely be able what you need to do in any video editing software.

Once you’ve imported all your files, roughly align them along the timeline and match the audio to video 1 to 1.

Step 3 – Synchronise your audio to your video

Now comes the step where you’ll thank yourself that you stood somewhere in public and clapped at your aircraft! For synchronisation between your audio and video, first go and find the three distinctive spikes in your audio waveform:

Screen Shot 2018-06-15 at 8.24.54 AM
Clapping produces a characteristic short waveform like seen here

Next, open up your video timeline as far as possible to be able to drill down to the exact moment your hands meet on the video. Mark that exact spot in the timeline, then drag the audio spike to meet this point spot-on:

Screen Shot 2018-06-15 at 10.39.14 AM
Position the timeline exactly on the moment your hands meet and align the audio spike

Once you are reasonably certain that you’ve got a good synchronisation, go ahead and run the video a few times to check if you’re happy with your work. The resulting feed should look something like this:

If you’re happy with what you’re seeing, proceed to the next step, if not, try moving the audio around a little bit.

As always, if you have multiple video/audio sets, go ahead and repeat for each one.

Step 4 – Export & Reimport your video

Next, you’ll want to export your video. This sounds counterintuitive as we haven’t yet done any cuts and editing, but you’ll notice, that at this moment the audio you synchronised is still only linked to the video (in green) but not attached to it (in blue):

Screen Shot 2018-06-15 at 11.53.05 AM
You’ll see the video only has linked audio (green) and not attached (blue)

This could be an issue, because once you start cutting pieces out of your video, you would effectively “unsync” the two again as the linked audio would stay in one piece while the video gets shorter.

To get around this, go ahead and export your whole video once (if possible at the highest possible quality) to bind/attach the audio to the video.

Once this is done, make a new project and import the resulting video. You’ll find that the previously linked audio is now part of the video itself:

Screen Shot 2018-06-15 at 11.56.10 AM.png
After exporting and reimporting, you’ll find the audio attached to the video.

Step 5 – Cut & Enhance

From here on, you’ll go ahead with your regular video editing workflow, find the best scenes of the video and cut/edit them as you like. If necessary, run a colour filter and do some touch ups. You’ll find that the attached audio stays synchronised throughout the entire process and you can smooth the cuts with transitions and/or manually changing the volume of the attached audio.

I find it also helpful to adjust the overall volume of the clip to be a bit more even. When the drone is taking off (i.e. close to the recorder), I cut the volume a bit while at the same time raising the volume when the drone was flying at 60m altitude.

I find that even with my medium priced audio recorder, the drone’s sound is still audible in the clip even though it’s almost out-of-range for humans when flying at maximum legal altitude (if you’re in a country where 120m or 150m altitude are allowed, you may find that you can’t hear anything anymore though…).

Finalizing this step will give you a nicely cut video with natural background sounds, just as if you had shot the video on your GoPro or on your phone:

This could already be all you want to do, but you may opt to do one more step.

Step 6 – (optionally) add additional audio, like background music

If you like, go ahead and add some soft music in the background. Of course, the video is already much improved by adding the environmental sounds of the place you’re filming, but maybe you can still improve by adding some nice instrumental video.

For a comparison between all the different steps, you can have a look at this video, where I deconstructed all the single steps and you’ll find the difference between each step:

And that’s it – export your movie as you would usually and share on your favourite sharing platform – I like Vimeo (as you may have noticed).

As always, thanks for watching/reading and hope this tutorial was useful for you.

In case of any questions, feel free to let me know on Twitter or Reddit.

See you next time!

Flo