Editing Audio in Audacity
Sometimes you will find that you need to edit dialogue in a video or podcast - or to alter part of a soundtrack to make it suitable for your personal use; this is where Audio Editors come in! In this chapter, we will be giving you a brief introduction to of the most popular free audio editors: Audacity.
Note: Audacity is available for Windows as well as Linux
In most of the popular Linux distros, Audacity can be installed from the Software Centre. The screen below shows two Audacity versions available on a Fedora system:
Select the version you require and click "Apply" (-or "Install" on other distros) to begin. Once installed, Fedora gives you the option to run the application. In other distros, simply click on the Audacity icon to start it:
When you run Audacity, the splash dialogue will display giving you useful links to help and tutorials. When you are happy to continue, just click on the "OK" button:
An empty Audacity main window should then display:
To load in an audio file to work on, simply choose:
File → Import → Audio :
Most versions of Audacity that reside in the Software Centre by default, will have support for proprietary audio formats removed. For example, you will see the following message if you try to import an MP3 file into one of these versions:
This version of Audacity was not compiled with MP3 files support
If you need support for MP3 or other proprietary formats, you'll need to go back and install a version of Audacity that has this. Generally, this version is known as Audacity Freeworld - and you can see that it is listed in the section above on Audacity installation - underneath the version we installed. Note that, in our example, the Freeworld version is sourced from RPM Fusion, rather than the Fedora main repository.
Once you have selected your file, Audacity will display a dialogue asking you if you wish to edit a copy of the file, or work on the original file directly: always choose the former (-unless you have a really good reason not to):
If you have a microphone attached to your PC then you can use Audacity to record your speech directly! If you already have a webcam configured (-e.g. for video conferencing) then you can use this as an input device. In addition many PC headphones now include a microphone (-this will provide the best quality usually) and, these days, many laptops now provide an integrated microphone as standard.
In our experience, the audio quality attained using the combination of headphones with a microphone boom (-and noise suppression) recorded via Audacity provides a much superior audio quality than using a webcam - and a more reliable method than using KDEnlive screen capture.
Before you begin - you'll need to make sure that your your microphone is configured. This is normally the same process in all the main distros with slight differences. For example, in Fedora, you configure it via the Fedora Sound menu or the Ubuntu Sound menu - both on the top panel of the desktop. Please see our article on Skype Audio Setup, which shows how to configure audio input.
To begin audio recording, simply click on the "Record" button:
If your microphone is correctly configured, you should see a waveform displayed in the main part of the window (-note this will be a mono signal, unless you have two microphones configured) as you speak:
To stop recording, simply click on the "Stop" button:
To select a section of the audio track, click first on the select tool icon:
Left-click your mouse in the graph area - at the start of the sequence you wish to select (you can fine tune this using the left or right arrow keys); then, holding down the SHIFT key, left-click at the end point.
Alternatively, holding down the SHIFT key, click on the start position then use the arrow keys to highlight the selected area (-whilst keeping the SHIFT key depressed); once the correct area is selected, release the SHIFT key.
The selected area should now be be shown with a lilac background:
If you wish to remove everything outside of the selected area, you can choose:
Edit → Trim :
To check that the selection contains the audio you require, press the SPACE key to play the selected area:
It is not possible to cover all that you can achieve in Audacity here (-check out the "Further Reading" section below if you want to dig deeper) but, once you have a sequence selected, you can do one of two main things:
- Replace it completely with a generated sound from the "Generate" menu:
- Apply an effect (-sound as reverb, speed up, bass enhance, etc) to the selected clip using the available options in the "Effects" menu:
Once your edited audio file sounds as it should, you will need to export it for use in other programs. To export the whole audio file select:
File → Export...
To export just the selected part, choose:
File → Export Selection...
Enter the desired filename and click on the "Save" button to create the final file.
Unless you are supremely confident that your sound clip is now perfect, it does make sense to save your current project before you quit, using:
File → Save
Enter the desired filename and click on the "Save" button to save your project, as an .aup file, for later editing.