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Newsletter #63 - July 23, 2005

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.
SampleInputI'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... Sample OutputAudacity 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...

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

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
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:
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:
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!!!
Label Track
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.
Envelope Tool

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.

Export - render an audio file from the project
WAV, MP3 and Ogg Vorbis are the choices of file types. We'll go with WAV, the one that works best in Movie Maker and Photo Story.
In addition to some MM2 users having problems with MP3 files, that option in Audacity needs an add-on LAME MP3 encoder. 
Ogg Vorbis files are not accepted as source files by Movie Maker or Photo Story.

Conclusions and Closing
Audacity works and works well... I didn't run into any issues as I exercised it to prepare this newsletter.
To recap a little... from the Movie Maker environment, you make a WAV file with whatever tools you have, edit it in Audacity, and export a new WAV file to take back to Movie Maker. Use the same process when working with the audio/music for a Photo Story 3 project.
Audacity has other features that have no relationship to Movie Maker, such as:
Here's part of Jingle Bells, with the display rotated 90 degrees from how it appears in Audacity.

Have a great weekend...