Monday, April 9, 2007

Realtime MFCC and LPC analysis

As I said on the previous blog entry, too much things done in CLAM this Easter. We fully dropped Fltk visualization module from the main libraries. Zach Welch (one of the active new commers) ported Voice2Midi to Qt4 and we moved a subset of the Qt3 visualization module to the SMSTools and dropped the rest. (Zach prepared a set of patches to port it to Qt4 but let's wait until the rewrite). All those drops mean that CLAM size has been reduced to a half of its former size: less mainteinance and faster entry for the new developers.

A few examples stopped being functional because they used Fltk Plots. One of them the LPC_example. It compiled by disabling visualization rendered the example useless. I decided to convert it into a Network Editor example.

After some hacking i had this piece of network working.

After some designer and prototyper hacking i got this interface:

Trying to understand the meaning of the LPC I also added a new output the spectral envelope:

So it captures the spectral envelope which is gonna be very useful for the vowel synth.

Then a user asked for realtime MFCC. As we already had the processings but using portless interface, and LPC visualization could be reused for MFCC, i also took this task. The result:

Mixing it all in a single analysis interface

Vowel formants are even more clear in MelSpectrum that in MelCepstrum or the Spectrum it self. Another idea to be used for the Educational Vowel Synth.

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