function?[tpitchFRpath]?=?pitchestimate（xfsparam）
%?PITCHESTIMATE?High-accuracy?pitch?estimation
%???[TP]?=?PITCHESTIMATE（XFs）?computes?a?pitch?estimate?P?at?times?T
%???for?the?signal?X?sampled?at?Fs?Hz?using?default?parameters.
%
%???[TP]?=?PITCHESTIMATE（XFsPARAM）?uses?the?parameter?values?specified
%???in?the?parameter?structure?PARAM?which?must?have?the?following?fields
%???（units?in?parentheses?default?values?in?brackets）
%
%??????minpitch???????????minimum?detected?pitch?（Hz）?[75]
%??????maxpitch???????????maximum?detected?pitch?（Hz）?[400]
%??????timestep???????????window?hop?（s）?[0.01]
%??????voicingthreshold???signal?level?required?for?voicing?detection?[0.4]
%??????silencethreshold???signal?level?required?for?silence?detection?[0.05]
%??????maxcandidates??????number?of?pitch?candidates?to?consider?per?frame?[4]
%??????octavecost?????????penalty?for?pitch?halving?[0.04]
%??????voicedunvoicedcost?penalty?for?switching?voiced/unvoiced?between?frames?[0.2]
%??????octavejumpcost?????penalty?for?switching?octaves?between?frames?[0.2]
%
%???The?pitch?estimation?algorithm?is?based?on?the?Praat?pitch?estimator?described
%???in?[1].
%
%???References:
%???[1]??P.?Boersma?“Accurate?Short-Term?Analysis?of?the?Fundamental?Frequency?and
%????????the?Harmonics-to-Noise?Ratio?of?Sampled?Sounds“?IFA?Proceedings?17?1993
%

%?check?number?of?input?arguments
error（nargchk（23nargin））;

%?setup?default?parameter?structure?if?none?specified
if?nargin<3
??%?define?default?algorithm?parameters?see?[1]?for?details
??param.minpitch???????????=?75;???%?Hz
??param.maxpitch???????????=?400;??%?Hz
??param.timestep???????????=?0.02;?%?seconds
??param.voicingthreshold???=?0.4;
??param.silencethreshold???=?0.05;
??param.maxcandidates??????=?4;
??param.octavecost?????????=?0.04;
??param.voicedunvoicedcost?=?0.2;
??param.octavejumpcost?????=?0.2;
end;

%?compute?size?skip?overlap?and?nfft?in?samples
winsize?=?round（fs/（param.minpitch/3））;?%?use?3?for?pitch?detection?use?6?for?HNR
winskip?=?round（param.timestep?*?fs）;
winolap?=?winsize?-?winskip;
winnfft?=?2^nextpow2（winsize?*?1.5）;

%?define?window
win?=?hanning（winsize）;

%?define?vector?to?demean?local?segments
demean?=?ones（winnfft1）;?demean（1）=0;

%?compute?auto-correlation?of?window?and?its?reciprocal
rwin?=?real（ifft（abs（fft（winwinnfft））.^2））;
rwinrecip?=?1./rwin;

%?step?1.?determine?windowed?frames?of?speech
xbuf?=?buffer（xwinsizewinolap‘nodelay‘）;
r?=?diag（sparse（win））?*?xbuf;

%?step?2.?compute?auto-correlation?of?all?segments
r?=?real（ifft（（diag（sparse（demean））*abs（fft（rwinnfft1）））.^2[]1））;

%?step?3.?divide?by?auto-correlation?of?the?window
r?=?diag（sparse（rwinrecip））?*?r;

%?flip?matrix?top/bottom?halves
r?=?fftshift（r1）;

%?define?time?lag?and?time?lags?within?our?pitch?range
tau?=?（-winnfft/2:winnfft/2-1）‘/fs;
mintau?=?1/param.maxpitch;
maxtau?=?1/param.minpitch;
goodtau?=?tau>=mintau?&?tau<=maxtau;