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Chapter 4. Optimizing Your Sound Files

When you have captured your audio source material, there are three critical steps to take before you integrate audio into your web site:

You can perform basic sound editing with any digital audio application that has routine cut, paste, and fade features. The sound-editing application we will refer to in this chapter is Macromedia's SoundEdit 16 (Macintosh and Windows). However, the concepts we discuss are the same for any basic sound editor, including CoolEdit (Windows), Sound Forge by Sonic Foundry (Windows), and Pro Tools by Avid (Macintosh and Windows NT).

Applying digital effects to your sound files is the most creative editing step, but it can also be the most confusing and troublesome. You can, for example, add too many effects and quickly lose track of what you've done to a file or how to backtrack to an earlier state. You can also add subtle effects such as reverb, delay, and equalization, or apply more drastic, sound-altering effects such as pitch-shifting, time expansion, and reverse. Learning which digital effects to use, and how and when to use them, takes practice and experimentation. In this chapter, you'll find guidelines to help fine-tune your application of digital effects.

Web mastering is the final optimization process before you encode your sound files into a web format. Audio files need to be custom-tailored for their respective output mediums: radio, film, television, home stereos, and of course the Internet. In this chapter, we will also discuss the techniques used to prepare sound files for digital delivery, drawing from traditional CD mastering techniques such as normalization and equalization.

By removing unwanted artifacts and glitches, applying the appropriate effects, and properly mastering your sound files, you greatly enhance your web soundtrack or voice-over. This chapter familiarizes you with all three of these techniques which will help bring the overall quality of your sound files up to professional broadcast standards.

4.1. Basic sound editing

After capturing your raw source material, you'll probably have to remove unavoidable, extraneous noises such as pops or clicks, system noise, 60 Hz electrical hum, or throat-clearing noises and coughs.

Properly cleaning up a sound file can be a time-consuming process. To capture the cleanest signal possible, you should start with a recording that has good dynamic range, optimized levels, and little system noise. Remember, the higher the quality of the original recording, the better the final edited version will sound when compressed for web delivery. A few extra minutes of planning in the recording studio can save you hours later in the editing studio.

SoundEdit 16

Macromedia SoundEdit 16 is a common digital audio application used in the multimedia industry. It is often bundled with software packages such as Director Studio. SoundEdit 16 is a stereo two-track editor featuring standard audio effects such as normalization, EQ, reverb, and delay as well as cut and paste features. It also provides support for all major web audio formats. For the latest updates and plug-ins, visit http://www.macromedia.com. Note that audio applications such as SoundForge and CoolEdit perform the same functions as SoundEdit 16.

4.1.3. Removing embedded artifacts

The final and most difficult step at this stage is to remove unwanted artifacts embedded within passages of music or voice-over phrases. Such artifacts must be carefully removed or reduced in volume without affecting the desired sound. In some cases, if the unwanted artifact occupies only a few milliseconds of time, you can simply delete that portion without detecting any major difference in the playback of the sound file. In most cases, however, you will have to settle for reducing the amplitude or volume of the spike or unwanted region to avoid a perceptible gap or glitch.

For longer playing artifacts, here are a few other techniques.

Beware of degradation

Removing embedded artifacts requires a delicate trade-off between allowing for some form of file degradation to fix the error and keeping the original, louder, more noticeable glitch. Regardless, be aware that the process of using volume and EQ to remove unwanted noises overlaying a mix of other sounds causes some form of degradation to your sound file.

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