Sunday, January 20, 2013

Software Spotlight - Audacity

And we're back with the second entry in my planned series, the Software Spotlight!  Today I'll be talking more-or-less briefly about a program I've used a lot - open-source audio editor Audacity!  And it works on all three major operating systems (Windows, MacOS and Linux) so that's a plus.

Image courtesy of

I'll start off by saying I am far from being an expert on sound engineering and editing.  As always, I'm just trying things out and figuring it out as I go - I've been doing this for years with various software, even back when the most complex image and sound manipulation programs I used were Microsoft Paint and Sound Recorder (hey, I had to start somewhere)

So Audacity's interface is pretty straightforward - in fact I find it's one of the easiest interfaces I've learned to use, since everything is relatively intuitive.  All the main audio-related buttons like Play, Pause and Stop are all in the top-left - nice, big round buttons with their ubiquitous media-related symbols.

Once you open up an audio file or record your own, you're presented with one or two sound bars (depending on if it's mono or stereo) representing the sound data.  In the snapshot below I've opened up Episode 1 of the Blender Podcast by Thomas Dinges and Campbell Barton.

This already presents us with several options and various information about the audio file.  We can see straight off the bat that this is a stereo track, it runs for over 14minutes (you can quickly get a more detailed reading by selecting the whole track with Ctrl-A and checking those three value boxes at the bottom) and that the audio track itself looks to be an acceptable volume.  That last one is easily detectable by checking the "intensity" of the blue sound wave data - this one looks pretty "stable", with only a few spikes.
The interface itself also gives us several options to tweak from the get-go, such as the operating system's input devices (in Linux I believe these would be the ALSA and pulse shown in the above snapshots), number of channels, and which physical input device you're going to be using - in my snapshots it's set to a USB microphone I've been testing out.

There are also several selection and playback tools in the top right, along with output/input levels, output/input volume, and various generic tools such as cut, copy, paste, undo/redo, and the zoom buttons.  There are also two very handy little tools next to the Cut/Copy/Paste buttons which can either take a selection and isolate it by deleting everything that's not selected, or turn that selection into dead silence.  More practical than doing everything by hand.
Still on the interface, there are also 6 different selection and editing tools - of which I've only used half in the four to five years I've been using Audacity.  I haven't touched the zoom tool in a few years, for instance, since I always use Ctrl-MouseScroll to zoom in and out.  A couple of them I've never even tried, such as Draw and Multi-Tool.  Time-shift I've never used much, but basically it takes the whole track and shifts it along the timeline.  I've never really needed that function myself, since most of the audio editing I do is mostly format conversions (usually WAV to MP3), basic trimming and noise-removal.  However, it's probably very useful when lining up several smaller clips on several tracks.

Before moving on to the various effects, just a quick note - Audacity can also open several sound files at once and display them one above the other.  You can also Mute or Solo individual tracks, as well as change their volume gain and L/R balance - which is useful when trying to determine if that stereo audio is true stereo audio and not just the same mono track played on the left and right ;)

And now on to the effects.  To be honest I've only used about half of these so far, and since I upgraded to version 2.0 in Linux Mint, there's also 115 plug-ins that I've yet to dive into.  However I'll go over the ones I know best and use most often - more specifically the Amplify, Change Pitch/Speed/Tempo, Fade In/Out, and Noise Removal.  Unfortunately I can't seem to be able to take a screenshot with the menus open, so I'll have to go text-only.

Amplify and Noise Removal are by far the effects I've used the most.  Amplify is pretty straight-forward and self-explanatory - with it you can increase or decrease the volume of the selected audio.  It won't let you go over a certain amount, however - and this amount is different for every selected audio clip.

Noise Removal, on the other hand, is a bit more complicated.  I used to simply select the whole audio strip and set Noise Removal to it's lowest setting, but that's not how it works.  In order to remove noise, it needs a sample of that noise so that it can recognize it in the rest of the audio and remove it.  For a self-recording, like on a podcast or similar, the best way is to select several seconds of silence.  It won't be perfect silence of course, since the microphone picks up any background humming from your PC and anything else going on in the background, but that's the point.  The Noise Removal filter then uses that template and removes the noise from the audio track.
There are now several options and variables that influence how the noise and removed and how much of it, and these are relatively new so I haven't figured out what they do yet.

Fade In/Out is also quite straightforward - I usually use it when editing tracks that start or cut off abruptly, just to make them easier on the ears.  Essentially it takes the selected clip and fades it in/out from/to silence.
The last three effects that I'm going to quickly go over are Speed/Tempo/Pitch.  As you can probably guess, I had a lot of fun with these effects back when I started using Audacity ;)  Nowadays I use Change Tempo the most, since the video editor I currently use doesn't have an audio-speed effect yet.  Basically Tempo changes the speed at which the selected audio plays, while Pitch can take a clip and make it higher or lower-pitched.  Speed, on the other hand, does both at the same time.  Very basic effects, but sometimes quite useful.
There are also other effects like Reverse which I've used from time to time, or Wahwah, but that's pretty much it when it comes to the Effects I know enough about to warrant writing about them.  Like I said there are a lot of effects and the 115 plug-ins that have been added.

Well, I can't think of anything else to say about it, unfortunately.  It's one of my most-used programs, and has been for a few years now - it's been pretty reliable, it's cross-platform, and it's open-source :D

If you have any suggestions on how I could improve this series of posts, or software suggestions, or just general comments, please leave them below!  Thanks!

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