Join Garrick Chow for an in-depth discussion in this video Steps to take before attempting repairs, part of Cleaning and Repairing Audio with Audacity.
- As you probably know, Audacity is an incredibly powerful and robust tool for editing all kinds of audio projects, and being completely free it puts many of the same tools found in much more expensive programs into the hands of anyone who cares to download and install it. But there is one very important thing to keep in mind about editing in Audacity, and that's that Audacity is what is referred to as a destructive editing application. You may have heard the terms destructive and non-destructive before when it comes to editing everything from photos, to videos, to audio. Non-destructive editing refers to a program's ability to apply changes to whatever it is you're editing, while preserving the original file itself, giving you the option to completely remove your changes or only certain changes, and revert your file back to a previous or original state.
Audacity however, is a destructive editor. Just to illustrate this I'm going to go into my exercise files here, and I'll just grab one of the files we'll be using later, and I'll open that in Audacity. So for instance, if I were working in this file and I just made a selection of part of the waveform here, and I went to the Effect menu, and chose to amplify it, and it doesn't really matter what I do here, and maybe I add a fade-in as well. So any changes you make to your audio are made to the audio file itself, and they can't be removed other than with the Undo command. So I can undo the fade-in, and then I can undo the amplify effect.
Audacity does have an unlimited amount of undo's so you can undo all the way back to when you first opened the file. But although you can undo your changes to your files in reverse order, you can't go back and selectively remove an edit you made five steps ago, without first undoing the four edits you applied after it. So therefore if you're going to be doing extensive editing to a recording, I highly suggest saving your projects in steps as you go along, especially if you plan on doing a lot of experimenting with your files. As you make your changes, periodically choose File, Save Project As... and then save a new copy of your project.
By the way, note that you'll see this message that tells you saving your project means you're not saving an audio file, but an Audacity project file. That simply means that you're saving it in a format that can only be read by Audacity, but that's OK because it allows you to preserve things like multiple tracks, instead of saving an audio file where all of your tracks are mixed together. Saving an Audacity project file saves the project file, and a data folder containing all the information Audacity need to continue working on that project. But to get back to my point here, any time you're about to make a major change to your project, you should take a minute, and choose File, Save Project As...
and save a new copy of the project to work on. I'll just choose my Desktop for this example, and maybe I'll create a new folder, and I'll just call this the Compression folder. And you'll probably want to give your project say a progressive naming convention by adding a number at the end, or some other chronological naming method of your choice. That way if you ever edit yourself into a corner, you can go back and reopen the project in one of its earlier states and start again from there. So now I'm seeing this dialog box that says, "Project Depends on Other Audio Files. "Copying these files into your project "will remove this dependency. "This is safer, but needs more disk space." What this means is that because I opened that WAV file, and now I'm saving it as a project, Audacity needs that original WAV file to refer to within this project.
Now we can either choose, "Save without Copying", and Audacity will continue to work on that original file that I first opened, or I can click, "Copy All Files" and Audacity will make a copy of this WAV file to work on, leaving that original file untouched. So if you want to keep an original copy of your file without making any changes to it, you can choose, "Copy All Files (Safer)." If you don't want to see this dialog box again, you can choose, "Whenever a project depends on other files:" you can choose, "Ask me", "Always copy all files", or, "Never copy any files". I'll just leave, "Ask me" selected for now, but I'll choose, "Copy All Files (Safer)".
So now this is an Audacity project, and if I just hide it for a moment, here's that compression folder I just created, and you can see this is the Audacity project file, and this is the data folder that it created containing the audio file and other information it needs. You never have to go into this data folder, and I suggest you stay out of it. But any time you want to open the project, you just double click the project file, and it will open here in Audacity. Now it's telling me it's already open, so I can just click OK. Now it does take a little bit more time this way, but everything I'm going to be showing you in this course, and just about everything you do in Audacity, is a destructive edit.
So it pays to spend a couple of seconds, and the hard drive space, to keep progressive copies of your projects in case you ever need to go back. Now another option you have is to go to Audacity preferences, and here under, "Import / Export", by the way it's Edit Preferences if you're on Windows, and here under, "When importing audio files," you have the choice of, "Make a copy of uncompressed audio files before editing", or, "Read uncompressed audio files "directly from the original." What this means is if I have this option selected, any time I open a WAV file or an AIF file, Audacity will automatically make a copy of that file, which I'll then have to save to a separate location.
That way my original file will remain untouched, and I'll always have a copy to go back to. So if you're worried about ruining an original file, you can come into Preferences and just make sure this is checked. So those are a couple of things you can do to protect your original files as you edit in Audacity. All right, so with that little bit of house-keeping out of the way let's start looking at some ways to clean up audio in Audacity.