Envelope Points

Once a sound is attached to a frame in Flash ^®, you can use a maximum of 8 envelope points to manipulate that sound. Envelope points (appearing as little squares in the diagram below) are really volume controls that allow you to create effects such as panning, muting, and fading. The left and right channels have their own envelope points allowing the effects just mentioned. To create an envelope point, again represented by a little square, simply click in the channel window on the horizontal line (when you initially open the sound frame properties window). Click and drag the square left or right, up or down to achieve the desired effect. Dragging the envelope point all the way down mutes the sound.



The best use of envelope points is discussed in a tutorial entitled Layering Audio in Flash^® - the killersound technique™. In this discussion they are used to essentially mix several individual sound files together over the timeline. All the individual instrument that make up a song, such as bass, piano, etc, are recorded separately and imported into Flash(tm). Once each and individual instrument is placed in its own layer, we use the envelope points in each instrument or layer to design or mix the song according to our liking. This technique allows for lots of creativity and freedom. You can even build the visual presentation around the music if so desired.

Note that once you start a new instance of the sound, you have another 8 envelope points at your disposal. However, if you attach a sound at a frame and choose to loop the sound several times, you are still limited to the 8 envelope points over the entire conglomeration or loops, not just the first loop of the sound. For example, in the diagram below, the sound is looped 30 times but we only have 8 envelope points to use for the entire 30 loops. Envelope points can also be used to save file size. For example, suppose you wish to include an ambulance siren traveling from the right speaker to the left, beginning with a fade in and ending with a fade out. Generally a siren sounds two tones, a high and a low tone. The inefficient way to use the sound is to take a sound file that emulates the siren. This file may be 10 seconds in length. You can import this sound and attach it to a frame and complete the task. However, if you realize that a siren is made up of two tones or notes that simply repeat at different levels of volume, you can obtain a very small file sounding only the two notes and then, using Flash(tm)'s envelope points, you can create the illusion of the siren fading in and fading out, beginning from the left speaker and going to the right. The diagram below illustrates this point. Note that we have zoomed out immensely to show the entire sound canvas. As you can see we used a very small file and looped it about 30 times. Using this very small file, you manage to obtain a sound that may typically take 10 seconds to play and up to 10 seconds worth of file size.