Just as undesirable as shaky video, that we discussed in the previous post, is bad audio. Our tolerance for bad audio is quite much lower than for bad video!
By contrast, preventing bad audio is technically more complicated than shaky video.
In this post, I will discuss what bad audio is and what you can do to prevent, or at least minimize it when shooting video with your windows phone.
There are many aspects to bad audio. The sound may:
- be distorted
- contain too much noise, like refrigerator hum and wind or street noise
- have too much echo
- have poor frequency response
The main approach is to use a quality microphone and to place it as close to the sound source as possible.
Types of Audio
When you shoot video with your phone, it will include audio, whether good or bad. When you bring the clip into your editing program, the visual portion is placed on a video track and the sound portion on an audio track.
In addition, you can add a narration (also called voice-over) which is recorded separately, usually after the fact and in a quiet environment. You can also include background music and sound effects. These different types of audio are ideally placed on separate audio tracks so that you can adjust their relative volume. Nice background music can help to sweeten poor audio a bit.
The main difficulty with the built-in microphones is the fact that they are built in. You may want to be some distance from your scene to get a wide shot, but then the mics are also far away. They then tend to pick up ambient sounds as much as the sound you are interested in. Just try and record an interview on a sidewalk next to a busy street—it’s a disaster!
The next problem is that smartphones use automatic gain control (AGC), which is ideal for phone and Skype calls. Lumia phones use special microphones that have high dynamic range which is good. But AGC increases the amplification when the audio is soft, and turns it down when the sound goes loud. This is not the effect one wants when recording music, for example—it is better to have manual control over the recording levels.
When set correctly, the electronics won’t overload thus preventing distortion.
The Headset Jack
Most smartphones have a headset jack. A headset consists of two earpieces (either cups or buds) allowing for stereo sound, as well as a microphone for speech recording. The mic is positioned close to the person’s mouth.
The smartphone checks for the presence of a headset and disables the internal mics when a headset is plugged in. The resistance of a headset mic is about 2000 ohm and that is what the phone checks for.
The headset jack is used for connecting external microphones.
Recording with Internal Mics
If you have no other option, you can use the internal mics when shooting video.
Try and get as close to the source of the sound as possible (less than three feet)—even if you have to get a bit in a person’s face. At least the phone is small and not so off-putting. And you will get, if not good, useable sound. The same applies for recording narration.
Recording with External Mics
You can connect many different types of mics using the headset jack including lavalier, shotgun and handheld mics (there are some caveats that we discuss later in this post).
When used appropriately, these will allow you to record good sound.
Make sure you use a TRRS mic (e.g. Rode SmartLav +) or a TRS mic with a suitable adapter cable (e.g. Audio-Technica ATR 3350 iS).
When you have to shoot an interview, you can use the headset’s mic. Simply put the earbuds in your hand and hold the mic part close to the interviewee’s face, where the headset mic would normally go.
The headset mic is also good for recording narration.
The first caveat is that the default video app does not recognize mics or headsets plugged into the headset jack. Fortunately, the excellent ProShot app does and it costs only few dollars.
Note, if you don’t have an external mic or the ProShot app, you can still make excellent videos, you just need to be more careful.
The next caveat is the lack of control over the audio—you are at the mercy of the AGC. You have no idea what the sound is like or if it is even being recorded at all. This is particularly relevant if you are videoing and event like a wedding. If you discover afterwards no sound was recorded or it was bad, well, the event can’t be done over…
An advantage of the ProShot app is that it also displays the audio levels while recording your video.
Rather than relying on your smartphone, I suggest using a separate digital sound recorder like the Zoom H1. It uses professional audio electronics and allows you to monitor and control the audio being recorded.
You can place the recorder close to the sound source, leaving you free to move with your smartphone as needed for the video. The Zoom H1 has its own stereo mics making it good for handheld recording of interviews.
The downside is it takes an extra step to import and synchronize the audio with the video. The extra control and quality sound it gives you makes the extra work worthwhile.
It is also amazingly affordable.
Capturing good audio is vital to your video success. Unlike with video, your options of fixing audio problems while editing, is limited.
It is better to get it right from the start.
Making Good Videos with a Windows Phone