You can import most sound file formats in either the Windows or Macintosh version of Flash. All major sound file types, such as MP3 and WAV, are compatible on both versions. After you import a sound file into a Flash document, you can edit the resulting .fla file on either platform.

Flash CS3 can import the following sound file formats:

These sound file types are structural or "architecture" based, meaning that they simply indicate the wrapper used to encode digital audio. Each of them can use a variety of compression techniques or a variety of audio codecs. A codec is a compression and decompression module for digital media. Sound and video is encoded (compressed) with a specific technique by an application or device. After it is encoded, it can be played back (decompressed) by a media player that has access to the codec module. In order for a sound file to play on your computer, you must have the audio codec used in that file installed on your system. MP3 files, for example, can be compressed in a variety of bit rates and frequencies, as can WAV and AIF files. Once Flash imports a sound file, the wrapper type (AIF, WAV, AU, and so on) is stripped. Flash simply stores the sound file as generic PCM (Pulse Code Modulation) digital audio. Moreover, Flash converts any imported 8-bit sound file into a 16-bit sound file. For this reason, it's best not to use any precompression or low bit depths on your sound files before you bring them into Flash CS3.

You can decide which sound encoding to use for audio when publishing Flash document files to Flash movie files (.swf). Although the default Publish Settings in Flash CS3 is to export all audio with the MP3 format, you can export sound in several other audio formats. We note the benefits and drawbacks of each format in the list that follows.

Regardless of the format that you choose in your document's Publish Settings for exporting your sounds, you can individually specify a compression scheme for each sound in the Flash document's library. Furthermore, each format has specific options and settings that we'll examine later in this chapter.

Table 15.1 shows the compatibility of Flash's audio export formats with various platforms.

Because sound is different from other types of Flash content, some users find that increasing the layer height of the sound layers eases working with multiple sounds in the timeline. That's because a taller layer height provides a better visual cue due to the unique waveforms of each sound. To increase the layer height for individual layers, follow these steps:

Tip

Your movie's frame rate, as specified in the Document Properties dialog box (Modify

Flash CS3 offers a great organization tool for layers in any timeline: layer folders. To nest sound layers in a layer folder, create a new layer folder and then drag each of the sound layers to the folder. As you drop each layer on the folder, it will nest within the folder.

Event is the default Sync option for all sounds in Flash, so unless you change this default to one of the other options, the sound automatically behaves as an Event sound. Event sounds begin with the keyframe in which they occur and then play independently of the timeline. If an Event sound's duration is longer than the remaining frames of its timeline, it continues to play even though playback on the timeline has stopped. If an Event sound requires considerable time to load, the movie pauses at that keyframe until the sound has loaded completely. Event sounds are the easiest to implement and are useful for background sound scapes and other sounds that don't need to be synced. Again, Event is the default Sync setting in the Sound menu of the Property inspector.

The Start Sync option is similar to an Event option, but with one crucial difference: If any instance of that sound is already playing, then no other instance of that sound can play. In other words, the Start Sync option tells the sound to begin playing only if other instances have finished playing or if it's the first instance of that sound to play. This option is useful if you want to avoid the layering problem we discussed in the previous caution note for Event sounds.

The Stop Sync option is similar to the Start Sync option, except that any and all instances of the selected sound stop playing when the frame containing the Stop Sync option is played. This option comes in handy when you want to mute a specific sound in a crowd of others. For example, if you created a sound mixer with an arrangement of Button instances, you could assign the Stop Sync option to a mute button for each of the sounds in the mixer.

Stream sounds are similar to a traditional soundtrack in a video-editing application. A Stream sound locks to the timeline and has priority over visual content. When you choose a Stream sound, the Flash Player attempts to pace the animation in sync with the sound. However, when animations either get too complex or are run on slower machines, the Flash Player skips — or drops — the frames as needed to stay in sync with the Stream sound. A Stream sound stops when the Playhead reaches the last frame that includes the waveform of the Stream sound; likewise, a Stream sound pauses if the timeline containing the Stream sound is stopped. A Stream sound can be scrubbed; by dragging the Playhead along the layer's frames in the Timeline window, the Stream sound plays in direct relationship to the content as it appears, frame by frame. This is especially useful for lip-sync and coordinating the perfect timing of sound effects with visual events.

To use sound effectively, it's important to understand how Stream sounds work. When a Flash document is published as a Flash movie file (.swf) and the Sync option for a sound is set to Stream, Flash breaks the sound into chunks that are tied to the timeline. The bytes within the movie are arranged according to the linear order of the Main Timeline (that is, Scene 1). As such, if you have a Stream sound that stretches from frames 1 to 100 of the Main Timeline and the movie contains a total of 200 frames, the Stream sound's bytes will be evenly distributed over the first 50 percent of the file's bytes.

In this section, we'll show you how to stop an Event sound using two different methods. The first method uses a Stop sound on a keyframe in the Main Timeline (Scene 1). The second method uses a Button instance with a Stop sound on its Down state.

Now, we'll show you how to play and mute an Event sound by clicking buttons. You can place an Event sound on one Button symbol instance, and then a Stop sound on another Button symbol instance.

You may have noticed that, if you click the Play button repeatedly, new instances of the sound will begin to play, overlapping with the original playing sound instance. Regardless, the Stop Sync option will stop all of them. If you want to prevent the Play button from enabling this type of overlap, go back to the sound keyframe on the Play button and change its Sync option to Start.

You can also stop a single instance of a Stream sound. To do this, simply place an empty keyframe in the sound layer at the point where the sound should stop.

The Bandwidth Profiler also reveals something we touched upon earlier: Stream sounds export only the actual portion of the sound that's used in the timeline. In our example, 60 frames' worth of the atmospheres_1 sound was about 12K (at default MP3 compression, 16 kilobits per second, or Kbps).

You can stop the sounds that are playing in all timelines (including Movie Clips) at any point by doing the following steps in a Flash AS 2.0 document:

The stopAllSounds() action stops only sounds that are playing at the time the action is executed. It will not permanently mute the sound for the duration of the movie. You can proceed to re-initialize any sounds any time after the stopAllSounds() action has executed. If you want to stop playback again, you will have to enable another stopAllSounds() action or use a Stop sound.

This behavior locates a sound item in the Flash movie's library and establishes a reference to that sound, so that the sound can be played later. This behavior can also be used to play the sound.

In practice, you will use this behavior to set up references to any sounds that you wish to use the Play Sound behavior. For example, if you have three sounds in your Library and you want to prepare all three for later use in your Flash movie, you would add three Load Sound from Library behaviors to the first frame of a layer in your Flash document. In the following steps, you learn how to add this behavior to a Flash document.

Note

The audio options for Audio event in the Flash tab of the Publish Settings dialog box (File

This behavior, as the name implies, loads an MP3 file at run time directly from the Flash Player environment. Instead of attaching a sound from the movie's library, this behavior can access an external MP3 file residing on a publicly accessible Web server. Note that "streaming" here means that the MP3 file will begin playback as soon as enough of the file has buffered into the Flash Player.

In the following exercise, you learn how to use this behavior to play an MP3 file from a remote Web server.

As indicated by the previous note, you can specify relative URLs (or file locations) in the Sound Location field for this behavior's parameters. For example, if you save your Flash movie file (.swf) in the same location or folder as your MP3 file, you can simply specify the MP3 filename in the Sound Location field. You can also use relative path notation. For example, /myfile.mp3 would load the myfile.mp3 file located one directory above (that is, the parent folder) the Flash movie's location.

The Play Sound behavior plays a sound that has been set up with the Load Sound from Library or Load streaming MP3 file behavior. Remember that the Load streaming MP3 file behavior automatically begins playback of the MP3 file, and the Load Sound from Library behavior has an optional parameter that automatically begins playback as well. You can use the Play Sound behavior to

In the following steps, you learn how to add a Play Sound movie to a Button instance.

The Play Sound behavior is the first Sound behavior discussed in this section that has different events from which you can choose in the Behaviors panel, as shown in Figure 15.12.

Figure 15.12. The event options available for behaviors attached to buttons

If you prefer the Play Sound behavior to activate with a different mouse event, you can choose another option in the Event combo box.

This behavior inserts the stopAllSounds() function into the code of the selected event handler (that is, a keyframe, a Button instance, or a Movie Clip instance). As we discussed earlier in this chapter, the stopAllSounds() function halts the playback of any and all playing sounds.

In the next exercise, you'll learn how to stop the playback of multiple sounds with the Stop All Sounds behavior.

You may have noticed that if you allow the movie to continue to play, the movie eventually loops back to the first frame and repeats. You can add a stop() action to the last frame of the timeline to prevent the Flash movie from looping.

Tip

To decrease publishing (or testing) time, change the Audio stream compression option to Speech in the Flash tab of the Publish Settings dialog box (File

Flash CS3 has basic sound-editing controls in the Edit Envelope dialog box, which is accessed by clicking the Edit button in the Property inspector. (As you may recall from previous sections, you must first select the keyframe containing the sound, and then open the Property inspector.) The Time In control and the Time Out control, or Control Bars, in Edit Envelope enable you to change the In (start) and Out (end) points of a sound. You use the envelope handles to create custom Fade-in and Fade-out effects. The Edit Envelope dialog box also enables you to edit each sound channel separately if you are working with a stereo (two-channel) sound.

A sound's In point is where the sound starts playing, and a sound's Out point is where the sound finishes. The Time In control and the Time Out control are used for setting or changing a sound's In and Out points. Here's how to do this:

Figure 15.14. The sound-editing tools and options of the Edit Envelope dialog box, which is accessed from the Property inspector

You can apply a handful of preset fades and other effects to a sound by selecting the effect from the Effect menu located in the sound attributes area of the Property inspector. For many uses, the Flash presets will be more than sufficient, but if you find yourself feeling limited, remember that more subtle effects can be created in an external sound editor. We describe Flash's preset effects in detail here:

Audio stream and Audio event have individual compression settings, which can be specified by their respective Set button options. If you click either Set button on the Flash tab, the same Sound Settings dialog box appears — it is identical for both Audio Stream and Audio Event, which means that the same options are offered for both types of sound. The Sound Settings dialog box, shown in various permutations in Figure 15.6, displays numerous settings related to the control of audio quality and audio file size. The type of compression you select governs the specific group of settings that appear.

Figure 15.16. The various options in the Sound Settings dialog box

The specific options that are available in the Sound Settings dialog boxes are always related to the compression, or audio-encoding scheme, selected in the Compression drop-down menu. That's because different compression technologies support different functionalities:

Although this is becoming less of an issue with the desktop versions of the Flash Players, it may still be important to consider that MP3 or audio playback may not be supported by all Flash Players, especially device-based players. You can use Flash Player 6 and higher features in the ActionScript language to check the capabilities of the Flash Player installed on a user's system. Using the System.capabilities object, you can check to see whether an MP3 decoder is installed. The specific property is

System.capabilities.hasMP3

More importantly, though, you can script your movies to check whether the Flash Player has access to general audio output. Some devices with the Flash Player may not have any audio output. This property is

System.capabilities.hasAudio

Audio settings in the Library panel are similar to those we discussed previously for the Publish Settings dialog box. These settings appear in the Sound Properties dialog box, shown in Figure 15.17. To access these settings, either (a) double-click the icon of the sound in the Library; or (b) select the sound as it appears in the Library and (i) click the Properties button, or (ii) choose Properties from the Library panel's options menu; or (c) right-click the sound symbol in the Library and choose Properties.

The top half of the Sound Properties dialog box displays status information about the sound file: To the far left is a window with the waveform of the selected audio; to the right of the waveform is an area that displays the name of the file together with its location, date, sample rate, channels, bit depth, duration, and file size.

The lower half of the dialog box is titled Export Settings. The first setting is a menu used to select the Compression scheme. The Compression options, and the subsequent compression-related options that appear in the other settings, are exactly the same as the sound options of the Publish Settings dialog box we discussed earlier in this chapter.

Figure 15.17. The Sound Properties dialog box enables you to control the compression settings and to precisely balance all other related settings for each individual sound in the Library.

Estimated results are displayed beneath the Export Settings. Here, the estimated final file size (after compression) of the clip is displayed, together with the compression percentage. This is an extremely important tool that is easily overlooked.

The buttons to the right of the Sound Properties dialog box offer the following options:

Fine-tuning your audio in the Sound Properties dialog box of the Library panel has three benefits. Foremost of these benefits is the ability to set specific compressions and optimizations for each individual sound. Another benefit is the Test button. This is an excellent way to audition your audio file and to know what it will sound like when it is exported with different compression schemes and bit rates — hearing is believing. Finally, the estimated results, which display how each setting will affect the compressed file size, is a powerful tool that helps you obtain the desired balance of quality and file size. In contrast, optimizing sounds with the Publish Settings is more of a blind process — it is not only more global, it's also more of a painful trial-and-error method.

One of the coolest things about Flash audio is that you can combine the two methods of controlling sounds, using both the Publish Settings and the Library panel's Sound Properties dialog box to streamline your work flow while still maintaining a relatively high degree of control over sound quality. (This method works best if you already have some experience with sound behavior in Flash.)

For example, let's assume that you have three different Event sounds in your Flash project. Two of these are simple button sounds. You decide that you won't require specialized compression for the sound used with the buttons. So, based on your prior experience of sound behavior in Flash, you go directly to the Publish Settings and set Event sounds to publish as MP3 at 48 Kbps with Best quality.

But the third sound is a loop of background jazz music that you want to be heard at near-CD quality. For this sound, you access the Sound Properties dialog box and try a number of combinations — and test each one — until you find a balance between file size and audio quality that pleases your ears. For example, you may decide to assign this sound to export as an MP3, stereo at 64 Kbps, with Quality set to Best.

Adobe has licensed the Fraunhofer MP3 codec, which supports streaming MP3 with a constant bit rate. However, neither Flash CS3 nor any Flash Player supports Variable Bit Rate (VBR), or VBR MP3, encoding for Stream sounds. VBR MP3 is a variant of MP3 that uses specialized algorithms to vary the bit rate according to the kind of sound that is being compressed. For example, a soprano solo would be accorded a higher bit rate than a crashing drum sequence, resulting in a superior ratio of quality to file size. There are a number of sound applications, such as Apple iTunes and the MP3 creation packs available for Windows Media Player, that export VBR MP3. If you have access to a sound application that exports VBR MP3, you'll be happy to know that you can import your VBR MP3 sound files, which are (theoretically) optimized for file size and quality beyond the compression capabilities of Flash CS3, and that you can maintain the compression of such files by doing the following:

If you choose to use VBR MP3 files in your Flash documents, you may need to test the following options of VBR compression in your MP3 creation software:

You may find that Flash CS3 will give you an import error for some VBR- (and CBR-) encoded MP3 files. If a particular setting creates an MP3 file that can't be imported into Flash CS3, then try another bit rate and/or quality combination. However, we have found that Flash CS3 has inconsistent behavior when it comes to importing MP3 files. For example, you may find that one VBR setting/combination does not work for a particular sound file, but that it works fine for others. Even more strangely, MP3 files that won't import into the Flash CS3 authoring environment will load just fine into Flash Player 6 or higher at runtime via ActionScript.

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It goes without saying that every Internet content creator strives to make every file and data transaction as small and efficient as possible to accommodate the majority of slow network connections in use today. As a Flash designer or developer incorporating sound into your projects, you'll want to properly plan sound usage in an effort to avoid 1MB .swf file downloads.

Table 15.4 explores many of the available network bandwidths that are in use on the Internet. However, as you've likely experienced, it's highly unusual to actually get the full download (or upload) speed out of your network connection. Variables such as network congestion, server load, and phone line conditions affect the quality of your network speed. Using the same formula that Adobe uses to determine approximate download speeds in the Bandwidth Profiler (within Test Movie mode), we calculated estimated bandwidth speeds for the connection speeds shown in Table 15.4. Because Flash CS3 displays compressed sound information in Kbps units, we converted these connection speeds into Kbps bit rates. More important, though, we also provided a 50-percent portion of this bit rate, as you'll likely need to save room for other Flash material, such as vector artwork, bitmap graphics, and animations.

Using Table 15.4 as a guide, try to plan your Flash project for your target audience. Actually, you may have more than one target audience. As such, you may need to develop several versions of your sound assets, with each version targeted to a specific connection speed.

Once you've decided your target audience(s), you can determine the maximum Kbps that your sound files should use. Table 15.5 shows you the bit rates of Raw, Speech, and ADPCM mono sounds. We don't include MP3 bit rates here because they're already calculated (and available) in the Compression menu of the Sound Properties dialog box: 8, 16, 20, 24, 32, 48, 56, 64, 80, 112, 128, and 160 Kbps. In Table 15.5, we show bit rates that are suitable for analog modem connections (14.4, 28.8, 33.6, and 56 Kbps) in bold.

In Tables 15.6 and 15.7, we calculate the file sizes that 1 second of mono (one-channel) sound occupies in a Flash movie file (.swf). Use the values in these tables as multipliers for your sound file's actual length. For example, if you know that you have a 30-second soundtrack file, the final Flash movie file size (containing just the audio) would be about 60K with ADPCM 3-bit, 5 kHz compression. Regardless of the actual content of the digital audio, these encodings will produce consistent file sizes based on length and resolution.

Sometime you may be handed a Flash document file (.fla) that has sound embedded within it and be told that the original sounds have either been lost or are no longer available. Here's how to extract a sound from such a file: