Introduction to
Audacity
Audacity is another of those great open
source utilities, one that is all about audio. It's a free download from
SourceForge. The latest version 1.2.3 is
what I'm using for this newsletter.
I'll focus on how Audacity relates to the
audio of Movie Maker and Photo Story, using WAV format files (uncompressed
audio) to bridge the applications... 
Audacity can't open DV-AVI, WMV or WMA
files.
My
multimedia sample this week is a music file, one of those player piano midi
files.
Click the note at the left to hear a one minute segment as it
sounded when heading from Movie Maker to TMPGEnc to Audacity... then click
the note at the right to listen to the 'enhanced' version after it was back in
Movie Maker. I used Audacity to make the sound
fuller...
... before getting into
it, here
are a few notes...
Notes...
I received my copy of the new book
Learning VirtualDub from Packt Publishing; it's been a
while, but worth waiting for. Having written the introductory chapter, I'm
now able to read the rest of the story. It's the first book published about
VirtualDub, VDubMod and AVISynth and I hadn't seen drafts of the other chapters
as the book developed.
... also in the book corner, Jan Ozer
sent a copy of his book about Premiere Elements to help me with my
assessment of the trial version. I'm all set for a few nights of reading on the
beach.
We (a few Microsoft MVPs)
concluded a successful disaster recovery effort this
week, with the poster of the problem doing a yeoman's job of manning
the controls... he was motivated. He was capturing live video to an
external USB2 hard drive via his digital camcorder, firewire connection, and
Movie Maker 2... 19 GB into the file, the USB cable was accidentally
disconnected, so the file was never completed to the extent that the header info
was included... the file couldn't be played.
Recovery happened by doing
microscopic surgery to graft the header info from a good file onto the
beginning of the incomplete one, using a hex editor... to me it strongly
demonstrated the value of newsgroups and forums combined with a
team effort on the part of a number of MVPs. The more complete story is now at the bottom of my Problem
Solving > Video Issues page.
.... on to the main
topic
Audacity
Here's the main working window of
Audacity. Let's start with Help on the main menu...
it opens a quick reference and says there's a complete reference
manual online. The help info is good.
This figure shows an audio file
that was just opened... the two tracks are the left and right channels of the
stereo file. I had just recorded it into the Audacity project by using the
Stereo Mix option as it played in the MM2 collection... more about that
later.
Open
File
If the working window is empty, you
open a file to start a project... if it already has audio tracks in it, you
can add more by importing another (Project > Import from the main
menu). You're not limited to having just one audio file in a project, nor
are you limited to having one open window or project.
Similar to Movie Maker and Photo
Story, you can work on an Audacity project and save the project file
(extension of .aup).
The audio file types that Audacity
can import or export are:
-
WAV - an industry
standard uncompressed file type... that Audacity can read and write... we'll
use this format to bridge the Movie Maker and Photo Story
files
-
AIFF - Apple's default uncompressed
files
-
AU - Sun and NeXT computer
format... slightly compressed
-
MP3 (MPEG-1, Layer 3) -
compressed audio files... about 10 to 1 compression... this option requires an
extra plug-in for Audacity
-
Ogg Vorbis - a compressed type
with settings you can adjust... designed as a free alternative to MP3...
the Ogg Vorbis files can't be imported into Movie Maker
You can save your Audacity
project with an .aup extension... and re-open it later for
continued work.
First Challenge -
Getting the Audio from Movie Maker or PhotoStory
to Audacity
Audacity needs a WAV file, and can't
open or import the audio track of a DV-AVI or WMV video file, nor can
it use a WMA file. Our first task is to record it
directly into an Audacity project or convert the file to a WAV
file that can be imported. Here's a few ways:
-
TMPGEnc is my
preferred option. Drag and drop a DV-AVI, WMV or WMA file onto its main
working window (cancel the wizard if it opens first) and use the main
menu - File > Output to File > WAVE File, and you have a file that
works great in Audacity. The audio track of a Photo Story 3 story works just
as well as a saved movie from Movie Maker.
-
The picture of the
Audacity working window shown above was taken using
the recording feature to capture a DV-AVI file
that was being previewed in an MM2 collection, using the Stereo Mix
option in Audacity. This is similar to capturing a playing file with the
narration feature of Movie Maker... preview/play it with Movie
Maker or the Windows Media Player as you record it with
Audacity.
The audio patterns of the WAV files
made by TMPGEnc and Virtual Dub looked identical and complete. The file
made by the stereo mix recording had two split-second breaks...
probably the result of the hard drive skipping a beat in the process. The
test file was a 2 minute, 12 second DV-AVI file captured from my digital
camcorder.
Besides being more complete, the
files from TMPGEnc and Virtual Dub showed better wave patterns... their
peaks fit more neatly into the audio tracks. I credit that to the software
automatically deciding how high a volume setting to use for the
conversions.
Working the File in
Audacity
When you have an audio
file in Audacity... what can you do with it? Having come from a Movie
Maker project, we'll focus on things such as fixing the audio by removing
noise, selectively raising and lowering volume through the track, and
making changes to add audio interest similar to adding interest to a clip by
using special effects.
.. the 'reverse' effect looked for by
many in Movie Maker isn't there, but it's in Audacity... so you can have your
video playing forward and the audio backwards... :)... I don't know
why!!!
You can use labels (menu > Project > Add Label...
) to annotate segments of the audio track to correlate it with
the segments of your movie project. The label track position is linked to
the audio track.
Select the portion
of the track to work on... the standard Control-A keys select the whole
file... so does clicking on the 'label' area to the left of the track you
want to select. Dragging your mouse cursor across a segment selects that
portion. Use Edit > Select to opt for 'Start to Cursor' or 'Cursor to
End'.
Once a portion of the file is
selected, the list of effects becomes active. Those that are
not self-explanatory, or warrant a comment, are:
Compressor - loud parts become softer without effecting the other
parts
Echo - select the time delay and a decay factor... I thought it
worked pretty neat in fleshing out the sound from one of the player piano
roll midi files, using a delay of 0.15 seconds with the default decay factor of
0.5.
Equalization - pick from a dozen preset curves or draw you own...
the presets include such things as RCA Victor 1947, Columbia LP and
RIAA
Fade In and Fade Out - fades the entire
selection linearly
Invert - flips the waveform vertically, reversing its phase
Noise Removal - select a small segment that should be 'silent' and
then tell it to remove all the noise similar to it. It works best when the good
audio is much louder than the noise being removed
Normalize - if you're going to mix some audio together, it's good to
normalize each part first
Nyquist Prompt - gives you a blank entry field for you to type in... for
advanced users only... if you don't know what it does, than you
probably don't want to use it
Phaser - combines phase-shifted signals with the original
Reverse - yes, plays it backwards
Wahwah - kind of sounds like the word reads
.... the 9 additional effects below the line are added plug-ins, and you
can add more. The help file cautions that a poorly written plug-in can crash the
app, and suggests saving your work first.
Control
Toolbar - Editing Tools
I'll point out two of the 6 editing tools, the ones that change the
volume of selected parts of the audio file.
Use
the Envelope Tool (the currently selected tool icon in the
image at the right... to change the volume of selected sections...
The
draw tool (the icon that looks like a pencil) to the
right of it is used to change the volume of a specific sample... you have
to zoom into the audio track a lot before you see individual sample points.
The app will tell you to zoom in more if you haven't drilled down enough.
Generate silence or selected noise
To
mute a segment, bleep a phrase with a tone, or generate white noise that sounds
a bit like a waterfall... use the Generate option from the pull down
menu.
Select a segment of the track first and then
generate the noise to fill it... experiment and preview it with any
settings.
Have a great weekend...
Movie Maker 2 and Photo Story
neat looking keyboard display to help the music
student study a midi file, with no functionality in terms of using
it. it can't play the file or convert it to other
formats.