While cleaning up my laptop’s hard drive I found an update to the audio editor I posted here last year. Not radically different, but maybe useful to someone.
Its new feature is the loop function. Toggle the loop button and playback loops between the start marker (S) and the end marker (E). Just like you’d expect.
Next to this single new feature there’s a new waveform display that I really like.
In the old version the waveform shape was rendered by drawing vertical lines next to each other for each pixel from left to right. The new version draws a much nicer vector shape that is less processor intensive as well.
The Flash app
Download the ActionScript source code and files for this project here.
What happens is that for each pixel the maximum and minimum sample value is polled. Those values are stored in two arrays. Then the array of maximums is used to draw the top half of the waveform and the array of minimums for the bottom half. Together the two halves form a filled shape.
Like in the earlier waveform display the render method changes when zoomed in. If the zoom level is high enough (when one pixel represents less than forty samples) the filled shape is replaced by a single line. I find a single line easier for close inspection of an audio signal and most audio editors work like this.
The mouse interaction remains the same as well: Click on the waveform and drag up or down to zoom and left or right to move, and even both at the same time! I still like this behaviour a lot. First saw it in Steinberg WaveLab.
A note: This waveform display works well for audio files of a minute or less in length. The longer the file the less precise the waveform gets. This is because a fixed number of samples is polled for each pixel. If the file is long one pixel represents a lot of audio, and if it’s polled at too large intervals the polling results get less and less precise. I didn’t increase the number of polls because I found that slows down the screen redraws too much.
The audio in this example is Untitled Locked Groove #3 by Snd which appeared on their Systems Medley / Planets 7” from 2000 on City Centre Offices. I listen to their records a lot. Good programming music as well. :-)
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