fbana3.m

来自「这是一个用于语音信号处理的工具箱」· M 代码 · 共 134 行

% Function: perform third stage of the Formant Based Linear Prediction Analysis
%           ==> allocate the formants

function  [FF,FB,Froot]=fbana3(signal,basic,cofa,voicetype,nframe);

%retrieve the basic specification
F_len=basic(5);
O_lap=basic(6); 
Order=basic(4);
M_len=F_len-O_lap;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%                                                %%%%%%
%%%%%%%                Formant Allocation              %%%%%%
%%%%%%%                                                %%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 % This step will create the following variables :
 %
 % 	FF = matrix of formant frequency
 %	FB = matrix of formant bandwidth
 %      Froot = matrix of formant roots

FF=zeros(nframe,5);  % matrix for formant frequency
FB=zeros(nframe,5);  % matrix for formant bandwidth
Froot=zeros(nframe,10); % matrix for formant roots

Fmethod=2;

%
% so far, Fmethod==2  produce the best synthetic speech
% 

if Fmethod==1

   %%----------------------------------------------------------------%
   %%                     Fmethod=1                                  %
   %%         Directly split linear prediction frame by frame        %
   %%         coefficients into 5 formant coefficients               %
   %%----------------------------------------------------------------%

   for kf=1:nframe
       cofa1=cofa(kf,:);
       %[fpoly,bpoly,ff,fb]=splitlp3(cofa1); % without pole modification
       [fpoly,bpoly,ff,fb]=splitlp5(cofa1); % with pole modification
       fpoles=roots(fpoly)';
       bpoles=roots(bpoly)'; 
       Froot(kf,:)=fpoles;
       FF(kf,:)=ff;
       FB(kf,:)=fb;
   end

   % smooth the formant track
   [FF,FB,Froot]=smfmtk(FF,FB);

elseif Fmethod==2

   %%----------------------------------------------------------------%
   %%                      Fmethod=2                                 %
   %%  Split linear prediction coefficients into formant and smooth  %
   %%  the formant track at the same time                            %
   %%----------------------------------------------------------------%

   [Froot,FF,FB]=smfrmt1(cofa);

end %% if Fmethod==1

    %%%-----------------------------%
    %%% smoothing the formant track %
    %%%-----------------------------%

 % find error frame
 for kf=1:nframe-1
     rcd(kf)=0; % rcd==0 --> no error ; rcd==-1 --> error
     if voicetype(kf)

        ff=FF(kf,:);
        fb=FB(kf,:);

        % the formant bandwidth is bigger than frequency
        if ~isempty(find( (ff-fb)<0 ))
           rcd(kf)=-1;
        % the second and third bandwidth to formant ratio should not exceed .5
        elseif fb(2)/ff(2)>.5 & fb(3)/ff(3)>.5
           rcd(kf)=-1;
        elseif ff(5)>4600
           rcd(kf)=-1;
        end
     end
 end

 %correct error frame
 for kf=1:nframe-1
    if voicetype(kf) & rcd(kf)==-1
       back=kf-1;
       while rcd(back)==-1
            back=back-1;
       end
       forward=kf+1;
       while rcd(forward)==-1
            forward=forward+1;
       end
       w1=kf-back;
       w2=forward-kf;
       cofb=real(poly(Froot(back,:)));
       coff=real(poly(Froot(forward,:)));
       cofa1=polystab(w1/(w1+w2)*cofb+w2/(w1+w2)*coff);

       rr=roots(cofa1);
       rr=rr(:)';
       rr=rr(imag(rr)>0);
       ff=angle(rr)/pi*5000;
       rad=abs(rr); % pole radius
       tmp=(4*rad-1-rad.^2)./(2*rad);
       fb=acos(tmp)/pi*10000; % formant bandwidth
       [ff,idx]=sort(ff);
       fb=fb(idx);

       if ~isempty(find( (ff-fb)<0 ))
            %zplane(cofa1,[]);pause(1);
           disp('Formant Estimation may not be stable in the following frame!');
            disp(kf)
            Froot(kf,:)=Froot(back,:);
            FF(kf,:)=FF(back,:);
            FB(kf,:)=FB(back,:);
       else
            Froot(kf,:)=[rr conj(rr)];
            FF(kf,:)=ff;
            FB(kf,:)=fb;
       end
    end
 end