> misleading to call this "spectral magnitudes" under Bit Allocation on > the > website. (Or are LPC coefficients actually also called spectral > magnitudes?)
The LPC coefficients can be interpreted as conveying the spectral magnitude information, try taking the DFT of the LPC synthesis filter spectra. > In the decoder, a signal is synthesized using the LPC synth filter. No - we use freq domain techniques, see sine.c: synthesise(). > That should > already be audible speech. But since the audio quality of pure LPC > systems is > low (you write of a "mechanical quality" in your thesis), you do the > following > trick: You get the DFT of the LPC-produced signal and extract the > harmonic > amplitudes - but from the RMS for reasons not well understood. You > then apply > the sinusoidal model (ie. "Reverse FFT"?) including phase information > derived > from the voicing bits. Effectively, you are enhancing the LPC > synthesized speech > by correcting the harmonic phases, resulting in increased quality. > > Did I get this right? Not really. The harmonic magnitures are extracted from the LPC synthesis filter spectra, and we also sample the LPC synthesis filter spectra to obtain the dispersive part of the phase spectra. > > PS: Off-topic, but what system did you write your thesis in? Is this > TeX or Troff? > I made a poor decision to use Word, various versions through the 90's. I did use Word basic for some automation. - David _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
