PapaJohn Productions
 
Newsletter #104 - May 20, 2006

A Shotgun Microphone

 

 
Wind noise has always been an issue with the built-in microphones on my camcorders, but only when it's windy... like when I visit Chicago. I've adapted by avoiding wind or editing out the audio segments.
 
I've read about problems with the internal mic picking up camcorder mechanical noises, but I've never noticed them. My Hi8 and mini-DV camcorders are both high-end consumer models, so maybe they have better microphone systems than the average model.
 
With the outdoor Renaissance wedding coming up, I figured it would be a good time to spring for a new item in my video kit, an external mic which is supposed to be able to eliminate such issues. On the recommendation of a 'professional' videographer, I opted for a Sennheiser MKE300... a $180 investment from B&H.
Shotgun Mic

Rather than wait for the wedding to test it, I thought it would make a good subject for this newsletter. The mic is supposed to eliminate wind and internal camcorder noises, and be directional to focus on the sound of most interest.  
 
 
... before getting into it further, here's a couple short notes...
 

 
Notes...
 
I started a 5 page article/tutorial about Photo Story 3 for MaximumPC magazine... busy writing some more.
 
Vista Corner... I reinstalled the earlier build 5365 to get the 'glass effects' to function again... and to see if my choice of reformatting the hard drive when moving on to build 5381 was the wrong one. It's running fine again, which points to my system not being sufficient to handle the added demands of the latest 5381 build.
 
Follow-up note about my first for-sale video on Google Video... submitted on May 3... the current status is still "Video is verified; stay tuned - it will be live shortly".
 
The website for the Renaissance Wedding is a new page in the Living Projects section of the website. Here's the direct link that Chris and Ash use and pass around to family and friends.
 
Chris-Ash
 
It's ready for the wedding videos... which I'll be adding one at a time as soon as I have the footage.
 
 
.... back to the main topic...
 

 
Shotgun Mic... first round testing
 
I've never had to think much about the camcorder's audio... just shoot what I wanted, capture it to Movie Maker, and edit. If there was wind noise, chop that part out and use the rest. That's kind of how I approached this first round of testing.
 
Here's the test arrangement...
The test is meant to check two things: the effects of wind noise, and how directional the shotgun mic is... how does the captured sound fall off as it rotates from the subject to the opposite point?
 
These video snippets are the results of this first round of tests:
the camcorder using the built-in mic.
using the shotgun mic.
The wind noise seems resolved by the mic... but there are some noises I'm hearing with the new mic that I didn't like... or maybe it's just that the mono sounds different than the stereo. I grew up thinking stereo was better than mono.
 
I slept on the subject as I thought about more tests...
 

 
Earbuds... to listen closer
 
I'd read about the need to listen to the audio coming into the camcorder as you shoot... again something I never had to do using only an internal mic that was always in the 'on' mode.
 
It can be pretty catastrophic to assume the mic is functioning when its not...  I read one account of someone shooting a wedding ceremony without realizing the audio wasn't being captured. He thought a flickering LCD light was sufficient, but it wasn't. It can happen if you plug the shotgun mic in but forget to turn it on... or if the battery is shot... or a connection isn't good.
 
Maybe the better reason is to simply know what sound is being captured, as it's much more directional than the internal mic, it's mono, and it's different than what your ears are usually hearing.
 
I plugged in a pair of earbuds and found immediately that I could hear sound in my right ear but not the left. The earbuds had a stereo plug, and the microphone port on the camcorder was stereo... I had assumed the mono input would be fed to both channels.
 
By moving the plug for the earbuds in and out of the camcorder port, it showed that both left and right played at certain points, but only the right played at others. I added a stereo to mono adapter... and with it fully inserted, I heard in both ears. That completed the hardware setup.
 

 
Audio Noise... one of the things you hear when you listen closer
 
My next test was simply sitting at my desk and listening to the sounds coming into the earbuds when the camcorder was in the recording mode and the only deliberate noise in the room was music from my stereo system....
 
First some Willie Nelson, followed by Beethoven. The Willie Nelson was more telling as there's total silence between words or guitar strums... I was hearing some low level audio hiss during the silence. It was the kind of hiss that is sometimes from speakers when the volume is pumped up too high... a maybe a low-level grounding issue.
 
I couldn't think of a way for me to ground the camcorder/mic system or do anything more to connect/align the two devices... the mic's mounting hardware is all plastic, so that couldn't be the issue.
 
It turned out the camcorder has a volume control, and the hiss was there because it was set to the max... a feature I'd never paid attention to as I wasn't as involved in listening during shooting. It sounded better when it was set about half way between the minimum and maximum.
 

 
Video WindOutdoor Testing... the Wind
 
Some wind came up, and this time it was good wind, when I wanted to go outside and capture the audio with the new mic.
 
Click the image or this link to hear how it sounded with the earbuds...
 
Capturing the Wind
 
Instead of running from the wind, the new mic let me face it and capture the sound of the rustling leaves, not ugly sound artifacts of wind on a mic...
 

 
Capturing the Camcorder Files
 
As I'm writing this, a newsgroup post gave me another dimension of the sound to think about. Someone posted that MM2 was reporting different properties of his captured video than VirtualDub and Premiere... the poster said Movie Maker 2 always reports the wrong audio sample rate for files captured with it, reporting a 32 khz sample rate when VirtualDub and Premiere report 48 khz for the same file.
 
My camcorder manual says that audio is recorded as PCM system (uncompressed) 48 kHz stereo when in 16 bit mode (2 channels, 1 stereo track), and 32 kHz when in 12 bit mode (4 channels, 2 stereo tracks). As I always use 16 bit, I did some checking and responded to the post.
 
I captured the same footage 4 times, using WinDV to get both type I and II DV-AVI files, Movie Maker 2 to capture it as a type I, and Movie Maker 1 to capture it as a type II.
 
The audio properties reported by MM2, VirtualDub and Premiere aligned... each said it was 2 Channel Stereo, a Sample Precision of 16 bits, and PCM Compression (Uncompressed)... but there are differences in bit and sample rates between the two file types.
captured by WinDVWinDV Capturing

type I
Bit Rate - 1024 kbps
Sample Rate - 32 kHz
 
type II
Bit Rate - 1536 kbps
Sample Rate - 48 kHz
 
captured by MM2
type I
Bit Rate - 1024 kbps
Sample Rate - 32 kHz
 
captured by MM1
 
type II
Bit Rate - 1536 kbps
Sample Rate - 48 kHz
I prefer aligning settings when moving from one hardware item to another, or between software apps. As my normal camcorder recording mode is 48 kHz, I'm going to make it my standard practice to capture as DV-AVI type II, using WinDV. Besides being able to capture the video as either type I or II, WinDV reports any dropped frames.
 
I've been running into more audio artifact issues lately than I used to... or I'm getting better at hearing them. Standardizing on capturing as type II DV-AVI files may help me understand it more.
 
This completes my tests of the new mic... and takes me a step closer to understanding the audio aspects of the camcorder and the files captured from it.
 

 
Conclusions and Closing
 
The new mic is a keeper. After the first round of indoor tests, I was seriously mulling over returning it for a different one or continuing without it. But the outdoor tests with the earbuds listening to what was being captured added a whole new dimension to my video-taking experience. It's no longer one of seeing the video in the viewfinder or on the LCD screen and letting the audio be whatever it is. The earbuds suck you into the audio environment, probably the same way an MP3 player or iPod immerse people into listening to their tunes as they move about.
 
You don't need an external mic to start using earbuds... borrow them from your portable audio player and give them a try, with whatever mic you have. 
 
When you're not using the shotgun mic, it should be unplugged, turned off, and taken off the camcorder... the info with the mic says the replaceable LR44 battery should be removed if the mic isn't being used constantly. A battery should last for about 200 hours.... and I picked up 2 spares last night for $1.19 each.
 
It's easier to shoot without the new mic. Shooting with it makes it more of a planned activity... but that's what happens as you take a step from a home video shooter to a videographer.
 
Our daughter-in-law and grands' annual dance recital is this weekend, so the new mic will get some testing there. The directional aspect of it should help focus the audio on the stage and reduce ambient audience sounds.
 
And then the big event for the new mic will be a week later, videoing the Renaissance wedding.
 

Have a great week...
 
PapaJohn