The Making of a Plug-In: Part 4 (Alpha Version)

After all the work that’s gone into this plug-in, it’s pretty darn cool to see it up and running in a host program!  I’ve been messing around with it a bit in Audacity, just trying out different parameter setting and seeing it all come together.  There’s more work to be done in order to take care of some additional issues that may crop up, but for the most part I have a working alpha version of the Match Envelope plug-in.  I will likely graduate it to beta once I take care of these issues, which isn’t far off, but in the meantime I am providing the alpha version for anyone interested to give it a shot (links at the end of this post).  I also recorded a short little video demonstrating the basic functionality of the plug-in (again, these particular audio files were chosen to illustrate the effect visually):

One of the primary issues that I need to address is differing sample rates between the source and destination audio.  This is something I have yet to try out in code, but I expect some sort of scaling of certain parameters will solve the problem rather than forbidding mixed sample rates (which would be a bit of a pain).

If, for example, we choose a window size of 30ms with the source audio at a sample rate of 44.1kHz, it will contain 1323 samples per window.  If the destination audio’s sample rate is at 48kHz, however, it will contain 1440 samples per window.  There can thus quite easily be a mismatch in the number of windows in an envelope profile between the two audio streams as well as window boundaries not matching up, which will cause the audio files to not sync or match properly.

This brings up another related issue, evident in the UI.  The Envelope Extractor contains the parameter for window duration, but what if the user selects a different value for the source envelope and the destination?  Right now it results in an incorrect match.  Should this be forbidden, or perhaps even ignored by forcing the same window duration on both envelopes?  Or perhaps there is a way to turn it into a feature.  I am undecided on this at the moment and need to do some testing and exploring of various options before addressing this issue.

In addition, I will have to decide on whether implementing user-saved programs is of any use in this plug-in.  Currently this functionality is not supported, but I think it would be a good idea to include some obvious presets, and allow users to save their own.

Other than that, I am excited to share the first distributable version of this plug-in!  The Mac OS X version has been tested on 10.6.8 and 10.8 in Audacity, and the Windows version using Windows 7 in both Audacity and Soundforge.  If you’re interested, give it a try, and though you’re certainly not obligated to, feedback is welcome:

christian@christianfloisand.com

Edit: Beta version available in Downloads

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