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.
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.
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...
-
Setup the tripod in the treadmill
part of the basement
-
Turn the TV on and play a Tivo
saved segment of 24... restarting it for each part of the
test
-
Place an indoor fan on a chair so
it's blowing on the side of the camcorder/mic when the camcorder
is aimed at the TV
-
Rotate the camcorder as it records,
so it goes fully around from TV back to TV...
-
Move a piece of cardboard in and
out of the space between the fan and the camcorder, so the wind goes up and
down like the gusts outdoors
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.
Outdoor 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...
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 WinDV
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
