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If you need to record live music or narration, or edit the tracks you have ripped with iTunes, you need another audio tool. For simple jobs, there is no better tool than Audacity, which is available free from its web site. (See Figure 6.)

Figure 06

Figure 6 Audacity download page

Audacity, which was developed by a group of volunteers and is distributed under a General Public License, is an open source application for recording and editing sounds. It is available for Mac, Microsoft Windows, and GNU/Linux.

You will also want to download the free LAME MP3 encoder to give Audacity the capability to export MP3 files.

Note that there are different versions of Audacity for Mac OS X and Mac OS 9. The Windows version supports Windows 98, ME, 2000, XP, and later. Sorry, Audacity is not supported on Windows 95 or NT 4.0. Audacity runs best on either platform with at least 64MB RAM and a 300MHz or better processor.

Although it is relatively simple to use, Audacity is a full-featured audio application (see Figure 7).

Figure 07

Figure 7 Audacity application

You can use Audacity to do the following:

  1. Record live audio.
  2. Convert tapes and records into digital recordings or CDs.
  3. Import and edit Ogg Vorbis, MP3, and WAV sound files.
  4. Cut, copy, splice, and mix sounds together.
  5. Change the speed or pitch of a recording.
  6. Remove static, hiss, hum, or other constant background noises.
  7. Alter frequencies with Equalization, FFT Filter, and Bass Boost effects.
  8. Adjust volumes with Compressor, Amplify, and Normalize effects.
  9. Apply a variety of built-in effects including echo, phaser, reverse, and more.

I use Audacity in my Flash work to edit, compress, and export MP3 files directly into the Flash Library.

After converting a track from an audio CD using iTunes, the track is usually much longer than I actually need for my Flash project, so I open it in Audacity for editing and trimming.

Trimming the length of a track in Audacity is a simple procedure. The track is opened in Audacity as a waveform. Highlight the portion of the track you do not want and press the delete key. Presto! The unwanted portion of the wave form is gone(see Figures 8 and 9).

Figure 08

Figure 8 Selected waveform

Figure 09

Figure 9 Deleted waveform

Audacity also contains a full featured set of effects that you can apply to any selected portion of the waveform (see Figure 10). I usually apply dynamic audio fade-ins and fade-outs in my Flash projects with ActionScripting, but you can perform a "hard" fade using Audacity if you want the fade to always occur at the exact same place in the audio track.

Figure 10

Figure 10 Audacity Effects menu

One effect I apply to all my audio files before exporting them into Flash is Normalize, which boosts the overall signal of weakly recorded tracks and diminishes levels for loud tracks without introducing any distortion. Normalizing your audio files helps to avoid large volume changes between different audio files in your project. If you find that you are repeatedly adjusting the volume during playback of your SWF file, normalizing all the audio tracks in Audacity should improve this situation.

You can do much more with Audacity than the basics I am covering here. The interface is simple and well implemented, encouraging experimentation and self-discovery.

Audacity also has a basic but well-written online help section with a Table of Contents, Index, and Search capability.

Figure 11

Figure 11 Audacity help

The last step before exporting a sound file from Audacity is to set its sample rate, sample format and bit rate.

The sample rate defines how many times per second the audio signal is digitally represented. It is measured in hertz (Hz) and is a measurement of the number of frequencies that a file can reproduce. The higher the number, the more accurate the sound sample will be compared with the original signal (also, the larger the file will be). A sample rate of 44,100Hz is equivalent to CD-quality sound.

The sample format, also referred to as bit depth, affects the range of amplitude or volume that the file can capture. A file with a bit depth of 16 has 65,536 amplitude values available to reproduce sounds contained in the file.

Set the default sample format and sample rate from the quality tab of the Audacity Preferences dialog box:

  1. Choose File > Preferences from Audacity’s main menu. The Audacity Preferences dialog box displays.
  2. Select the Quality tab.
  3. Choose the Default Sample Format and Default Sample Rate from their respective drop-down menus (see Figure 12).
Figure 12

Figure 12 Quality tab of the iTunes Preferences dialog box

I recommend using a sample rate of 48000 for DVD-quality audio; 44100 for music with a lot of dynamic range such as classical, opera, or jazz; 22050 for electronic and other music with more limited dynamic range; and 11025 for lectures and narration. If you have a fast-enough computer and enough disk space, Audacity recommends setting your default sample format to 32-bit float while recording and editing, but exporting the final mix as a 16-bit file.

Bit rate compression is a measurement of the amount of data stored for every second of audio. This is in contrast to the sample rate, which is a measurement of the frequency with which the signal is stored. The higher the bit rate, the greater the audio resolution and overall size of the final file. If you want small files, you have to settle for lower audio quality. If you don’t mind larger files, you can go with higher bit rates.

In Audacity, you set compression bit rates from the Preferences dialog box.

  1. Choose File > Preferences from Audacity’s main menu, which displays the Audacity Preferences dialog box.
  2. Select the File Formats tab.
  3. Set the export compression by choosing a value from the Bit Rate drop-down menu located in the MP3 Export Setup section of the tab (see Figure 13).
    Figure 13

    Figure 13 File Formats tab of the iTunes Preferences dialog box

  4. A good strategy to determine the best mix of quality versus file size for a given file is to choose a value in the middle of the drop-down menu, say 64 or 80, and listen to the exported file. If the sound quality is okay for the purpose at hand, go to the next lower setting, export the file, and listen to it again. Keep repeating this procedure, going down the list of options, until the sound quality of the result is unacceptable. At that point, move up one setting to the last acceptable value and then use this bit rate setting in the final exported file.

    Although this procedure takes more time, it guarantees the smallest possible file size while maintaining acceptable audio quality.

The file is now ready to be exported out of Audacity for use in your Flash projects:

  1. Choose File > Export as MP3 from the main menu.
  2. Select a location to save the file and click Save.

You’re done. That is all there is to it!

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