音频信号处理matlab代码

The routines provided here are: melfcc.m - main function for calculating PLP and MFCCs from sound waveforms, supports many options - including Bark scaling (i.e. not just Mel! but cannot do rasta). invmelfcc.m - main function for inverting back from cepstral coefficients to spectrograms and (noise-excited) waveforms, options exactly match melfcc (to invert that processing). rastaplp.m - the original main routine to convert waveform data into a sequence of feature frames. Outputs are both cepstra and spectra features, and options allow for selection of RASTA, PLP, both, or neither. (Cannot do Mel-scaling). m = rastaplp(d,sr,0,ord) is equivalent to m = melfcc(d,sr,'preemph',0,'modelorder',ord,'numcep',ord+1,'dcttype',1,'dither',1,'nbands',ceil(hz2bark(sr/2))+1,'fbtype','bark','usecmp',1); powspec.m - calculate the short-time power spectrum, basically a wrapper around Matlab's specgram. audspec.m - map the power spectrum to an auditory frequency axis, by combining FFT bins into equally-spaced intervals on the Bark axis (or one approximation of it). fft2barkmx.m - function to create the weight matrix that maps FFT bin magnitudes to the Bark frequency axis, used by audspec.m. fft2melmx.m - generates a matrix of weights to convert FFT magnitudes into Mel bands, just like fft2barkmx above. rastafilt.m - filter each frequency band (now in terms of log energy) with the RASTA filter. postaud.m - fix-up the auditory spectrum with equal-loudness weighting and cube-root compression. dolpc.m - convert the auditory spectra directly to LPC coefficients via Levinson-Durbin. lpc2cep.m - convert LPC coefficients directly to cepstral values. lpc2spec.m - convert LPC coefficients back into spectra by sampling the z-plane. spec2cep.m - calculate cepstra by taking the DCT/DFT of the log of a set of spectra. hz2bark.m - convert frequency in Hz to the auditory Bark scale. bark2hz.m - convert back from Bark units to frequency in Hz. hz2mel.m - convert frequency in Hz to the auditory Mel scale (either Slaney's or HTK mapping). mel2hz.m - convert back from Mel units to frequency in Hz. lifter.m - apply (or remove) weighting from cepstral dimensions. deltas.m - calculate delta features over a limited window, just like feacalc/calc_deltas etc. process_options.m - Mark Paskin's utility to parse long 'name', value pair lists (which I found out about through Kevin Murphy's KPMtools), used by melfcc.m. cep2spec.m - inverse of spec2cep, undoes the DCT. invpowspec.m - invert powspec.m i.e. go back from an STFT magnitude to a (noise-excited) time waveform. ispecgram.m - precisely invert the short-time Fourier transform performed by specgram, taking the same argument (but fudges inverting the window at the moment). invaudspec.m - invert audspec i.e. expand the condensed, nonlinear frequency axis to the full FFT detail. Intrinsically lossy, but does its best. invpostaud.m - undo the weighting and compression of postaud, mostly lossless except the very edge bands are lost.