Archive for October, 2008

Flash Actionscript 3 Waveform Generation Class

Friday, October 24th, 2008

In my last post, Plotting a Sound Wave in Flash AS3 I detailed a method to use when displaying audio data. The method itself works great, but due to Flash’s frame-based code execution and event processing the user looses input capabilities while the flash player chugs through millions of numbers adding, rounding and comparing. In order to make displaying an audio waveform easier on both the programmer and the user I wrote a class that analyzes a Sound object progressively, and dispatches a special event containing the analyzed data. The class will construct a left and right channel Vector, each containing one data point [a number between 0 and 1] for a given number of windows, between two positions in the sound. The left and right position are measured in samples and two types of analyzation are offered. Here is a demo of the class in action:

Screen Capture of Waveform Plot

Screen Capture of Waveform Plot

The calculated data can be reached incrementally through the WaveformEvent object which is dispatched every frame, or at the end of all analyzation in the Waveform object’s leftChannel and rightChannel properties. The details are listed in the documentation below.

Thanks to the Summit Projects Flash Blog and Thibault Imbert at ByteArray for their posts on the different techniques that went into my class.

Here is the source for my TextMate project: Sources
Documentation: class and event

And here is a Flex version (made in windows): // Thanks dem!
Sources (Flex version)

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