Tag Archives: audio

Make Good Videos with Your Windows Phone – Part 4

iRig Handheld Mic

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.

Bad Audio
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.

Smartphone Limitations
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.

Audio-Technica ATR 3350 iS

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 Caveats
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.

Zoom H1

Preferred Solution
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

Sound Reasons

A HAAC Microphone
A HAAC Microphone

When I bought my Lumia 620 I discovered that although it was a budget phone it had HAAC microphones and rich sound recording. I had absolutely no idea what that meant but it sounded good…

In this post I will discuss the audio technology of Lumia phones and why it is another sound reason to consider a Lumia phone.

The HAAC Microphone
Traditional microphones start distorting the sound when the level or amplitude becomes too loud. Nokia developed the patented HAAC (high amplitude audio capture) microphone. Basically there are two channels for the sound, one for regular sound levels, and one for very loud levels.

The software in the phone combines the channels intelligently. The result is that the phone is able to capture a very wide range of sound levels without distortion. (Links to a more technical description is given at the end of the post).

Rich Sound Recording
Sounds are captured and processed using 32bit software algorithms – that is high performance! This allows the software to improve the quality of the sound by providing wind noise reduction, microphone self-noise reduction, microphone equalizers (to fit product acoustics to frequency response requirements), camera autofocus noise reduction and automatic gain control.

On basic phones, like my Lumia 620, there are two microphones, one at the top and one at the bottom edge of the phone (or left and right edges when holding the phone horizontally).

When speaking on the phone, the lower microphone picks up your voice, while the top microphone captures ambient sound (mostly noise). The software uses the sound from the top mic to subtract the noise from your voice signal.

When capturing video, rich recording kicks in in a different way. Your phone is now held horizontally (or should be). The two microphones are now used to capture rich stereoscopic sound.

Once the sound from the two microphones have been cleaned up, they are combined with the information from the video camera into an mpeg container file (.mp4) and stored on your phone.

The diagram below shows the various components involved in rich sound recording.


Multiple Microphones
HAAC microphones are inherently omnidirectional which means it picks up sound equally from all directions. When you are videotaping a performance or a person speaking at a podium, you would ideally want the microphones to be directional, i.e. recording what you are interested in, and ignoring all other sounds. This is illustrated in the diagram below:

directional recording

The more expensive Lumias (not my 620 I am afraid) have four microphones: two facing in the direction of the camera and two on the back. This allows the software algorithms to filter out the unwanted sounds from behind the person shooting the video, thus giving one excellent directional recording ability.

The Lumia 830, which is the phone I covet, has only one microphone at the back so the directional effect is not as perfect as on the 930 but it is still pretty good and gives excellent surround sound recordings for your videos. This I think is a reasonable compromise for an “affordable flagship” phone.

If you are technically inclined you can view these Nokia white papers.

In the next post I will discuss how to use the audio side of your phone in your business.