Recording great video has never been easier. Anyone with the will to learn and a few hundred dollars for a DSLR can produce video that doesn’t look out of place in a movie theatre. Even smartphones can make professional-quality video now! Great visuals, however, are only one part of what makes a great footage. No matter how pretty things look, if the accompanying audio track is poorly recorded the finished product will suffer and seem amateurish.
In this tutorial, you'll learn how to use your smartphone and a lapel mic to record audio for video. We'll consider the equipment you need, what apps work as well, and important information such as:
- How to set up your phone for recording.
- Where to position the mic on your body.
- What clothes to wear when using a lav mic.
- What to do with the cable.
- How to set the recording up.
- How to sync the separate audio and video files.
- What file format to save the finished recording in.
The Perils of DSLR Audio
The microphones built into most modern DSLRs are, in a word, pitiful. They can capture the ambient noise of a scene but they are not capable of making truly usable recordings. In audio terms, the problem with DSLR microphones is that they have a low signal-to-noise ratio. That is, the noise of what you want to hear—the signal—is often mixed with the noises you don't want. While in-camera mics are useful as a reference recording they just aren't built for good quality audio.
A Quick Comparison
Camera Microphones at 5 Feet
This audio clip was recorded with my Canon 650D at a distance of approximately 5 feet. You can hear a lot of ambient noise in the recording.
iPhone Microphone at 1 Foot
This audio clip was recorded with my iPhone at a distance of about one foot. It's better, but not perfect. There is less ambient noise, but this is mostly because the microphones are much closer to the source of my voice. If you have a static composition in a quiet place and are able to rig up the iPhone just outside the frame overhead this is a workable solution in a pinch.
This audio clip was recorded using a microphone plugged into my iPhone. Much better! This setup allows for a much more flexible production style.
What You Need
To record good audio with your smartphone you need two things: a high quality mic and a professional recording app. Your smartphone’s built-in microphone and voice notes app won’t give you the results you want.
The Lav Mic
The best mic for recording speech and dialogue for video with your smartphone is a lapel, or lavalier, microphone. These small mics clip discreetly to a shirt and they’re often used in documentary production. Placed on the body, relatively close to the mouth, they’re able to isolate the speaker’s voice from environmental noise.
Whether you go with a dedicated smartphone or general purpose lapel mic, it’s important to get a decent quality one. There are hundreds of sub-$10 lav mics available on Amazon which, although they’ll sound better than your camera’s mic, are meant for live presentations and not recorded audio. When in doubt, choose a mic from a reputable brand like RØDE, Audio-Technica or Sennheiser—even their base models are solid products. Boutique mics like the HMNSound MicroLav, Giant Squid, and MicJ 044 also offer good value.
Audio Recorder App
To record high quality audio you need to be able to set audio levels and sample rate, monitor your inputs, view the waveform as you record, and output to a variety of different audio formats. The built in tools on iOS and Android can’t do this.
On iOS the RØDE Rec app is designed to work with the RØDE SmartLav+ I use and has all the features I need—RØDE has a history of supporting DSLR filmmakers.
RØDE competitor Tascam also has an iOS app: PCM Recorder Mk II. It's a free app and has all the necessary features.
Another great iOS app is bossjock studio. It’s designed for podcasters rather than filmmakers so includes a lot of podcast specific features. It is, however, more than capable of being used to capture audio as you film.
On Android WavePad Audio Editor Free is a professional audio recording app. Like bossjock studio, it’s designed more for dedicated audio producers but it has all the features filmmakers need.
How to Record Audio for Video With Your Smartphone
Once you’ve got the set up necessary, it’s time to start audio recording. For this tutorial we’re going to look at recording audio while you film, however, all the principles still apply even if you’re recording a voice-over before or after the video shoot.
Set Up the Phone
Your smartphone is a fantastic tool, but above all else, it’s a phone. If it rings during an audio recording, everything else stops. Before doing anything more, put your phone in Airplane Mode.
Position the Mic
The lav mic must be close enough to your mouth that it picks up sounds clearly but not so close that plosives and breathing noise becomes an issue.
Position the mic between 6 and 8 inches away from your mouth as centrally as possible. Most lav mics are omnidirectional so you can get away with having them slightly off axis. For the same reason you can move your head a small amount when you talk. Even still, the more central the mic is and the less you move your head, the better the resulting audio.
What to Wear
When recording with a lav mic, clothing is an important consideration.
The best thing to wear is a button down shirt as the mic can attach through the gaps in the buttons on the centre of the shirt. Failing that, a jacket or blazer with lapels works well. Round-necked t-shirts, jumpers and other tops that don’t have somewhere low enough for the mic to attach to are best avoided.
The fabric your clothes are made of also matters. Natural fabrics like cotton are less likely to rustle or create unwanted sounds than synthetic fabrics. To test whether or not a garment is suitable, rub two sections against themselves. The less noise, the better.
The cable connecting your smartphone and mic is incredibly important. If it snags or catches on anything it’ll mess up any recording you’re making. Even worse, it could end up breaking the mic.
Run the cable from the mic to your smartphone under your clothes. If you’re using a button down shirt, the cable should run out through the gap the mic is attached to.
The cable should never be stretched taut. Your smartphone should be placed close enough to the mic that there is plenty of slack. Similarly, the cable should never dangle as that makes it more likely to catch on something or be noticed in the final video.
When possible, the cable should be taped to your body. This ensures it can’t move too much while providing the mic with enough cable to move as much as it needs. Medical tape, the kind that is used with bandages, is your best choice: it sticks to clothes and skin alike without tearing or leaving gummy residue. And it's inexpensive!
Set Up the Recording
Record audio with the highest sample rate offered by the setup you’re using. My RØDE SmartLav+ and the RØDE Rec app record at 32 kHz by default, however they can record at up to 48 kHz. Look for higher data rates, too: 24-bit is preferable to 16-bit. Check what the maximum your setup allows is and use it. You want to record as much data as possible.
Before you record, test and set your levels. With the mic placed correctly talk as you will during the filming. Watch the levels to see that they aren’t too high or two low. The bar should peak at near -12 dB. You want to avoid clipping, which is when the quantity of signal exceeds the capability of your recorder (usually marked in red on your levels).
Sync Audio to the Camera
If you’re separately recording video and audio you need a way to sync the two in post. The best way is to use a production slate. Ben Lucas has a full tutorial on using production slates and another two on how to synchronise audio manually and automatically after you've recorded.
If you don’t have a slate, you can get by with just your hands. Clap them loudly close to the mic and in view of the cameras recording the take. If you’re shooting simple scenes with one or two cameras this will work fine. If, however, you’re filming something more complex a slate will make post-production much easier.
Save the File
While you can edit audio and video together on your smartphone, it’s better to do it in a powerful non-linear editor like Adobe Premier Pro. It’s important to give your editing app as much data as possible to work with so you don’t want to lose any information when you export it from your phone.
All the professional audio apps offer multiple file formats. To keep the highest quality audio possible, use a highbitrate or lossless format like Apple Lossless or FLAC. This gives you the most flexibility when editing everything together.
While larger productions will invest in a dedicated package of audio gear, using your smartphone with a small lapel microphone is a great first step toward good audio for your video productions. Lav mics aren't perfect: they don't provide the same quality of sound as a directional, powered, and dedicated microphone. For everyday and low budget videos, however, they are a smart way to maximize your production value with a minimal investment.
A lapel mic also makes a solid 'plan b' in a more complete audio kit, too. A common documentary tactic, for example, is to combine a lavalier microphone on the subject with a shotgun microphone mounted on the camera; a flexible and balanced way to record sound. A good-quality lav mic is an investment that will pay for itself many times over.