Granular Control over Audio Values
ActionScript provides granular control over audio streams, including discreet control over audio Channels.
Digital sound distills down to "sampling." Sampling an audio stream 44,100 times per second produces 44,100 discreet sample values, which are stored as numbers. Those numbers may be formatted in 8 bits (a Byte: 256 levels), or in 16 bits (two Bytes: 65,537 levels), or more. The more and larger the numbers, the larger the file size necessary to store the data, and the faster the bitstream necessary to transfer the data conveniently.
A principle known as the Nyquist Frequency postulates that to sufficiently capture data for human sensory consumption (et. al.), a data set must be sampled at roughly twice its frequency. Standardized human aural acuity can sense sound up to nearly 20,000 cycles per second ("Hertz"), so to satisfy the Nyquist Frequency sound should be sampled at around 40,000 Hertz, and in fact, the standard high quality audio sample rate is (in multiples of 11,250 Hertz) 44,100 Hertz. However, not all sound produces such high frequency information, and the sampling frequency may be moderated when superflouous sampling does little but increase the file size. This is very common with telephonic (voice-only) sound. Smaller file sizes and more modest bitrate requirements are appropriate when programming for mobile devices.
For a more in-depth review of audio compression strategies please see the Forensically Fit website.
Flash (ActionScript 3) offers a very robust Sound functionality that includes multiple Channels, Stereo, volume and panning controls ("Transforms"). Because Flash is tremendously adept at both mathematics and drawing it can be used to produce very sophisticated, Channel-specific graphical sound displays and interactive animations-even "Beat Detection" and various psychoacoustic manipulations. The example below is very simple-it simply generates a sort of Histogram for the sound values in the Left Channel of a stereo track of bird songs. More complex displays can be generated, including those as sophisticated as controlling the parameters of Perlin Noise, Fractals, and Particle Generators with the audio data values or their dynamics.
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