注释function Y=voice(x,f) %更改采样率使基频改变 f>1降低;f<1升高 f=f+0.15; f=round(f*1000); d=resample(x,f,1000); %时长整合使语音文件恢复原来时长 W=400;Wov=W/2;Kmax=W*2;Wsim=Wov; xdecim=8; kdecim=2; X=d'; F=f/1000; Ss =W-Wov; xpts = size(X,2); ypts = round(xpts / F); Y = zeros(1, ypts); xfwin = (1:Wov)/(Wov+1); ovix = (1-Wov):0; newix = 1:(W-Wov); simix = (1:xdecim:Wsim) - Wsim; padX = [zeros(1, Wsim), X, zeros(1,Kmax+W-Wov)]; Y(1:Wsim) = X(1:Wsim); lastxpos = 0; km = 0; for ypos = Wsim:Ss:(ypts-W) xpos = round(F * ypos); kmpred = km + (xpos - lastxpos); lastxpos = xpos; if (kmpred <= Kmax) km = kmpred;else ysim = Y(ypos + simix); rxy = zeros(1, Kmax+1); rxx = zeros(1, Kmax+1);Kmin = 0; for k = Kmin:kdecim:Kmax xsim = padX(Wsim + xpos + k + simix); rxx(k+1) = norm(xsim); rxy(k+1) = (ysim * xsim'); end Rxy = (rxx ~= 0).*rxy./(rxx+(rxx==0)); km = min(find(Rxy == max(Rxy))-1); end xabs = xpos+km; Y(ypos+ovix) = ((1-xfwin).*Y(ypos+ovix)) + (xfwin.*padX(Wsim+xabs+ovix)); Y(ypos+newix) = padX(Wsim+xabs+newix); end end

这是一个MATLAB函数，用于改变语音文件的基频，实现升高或降低语音的音调。函数输入参数x为原始语音数据，f为改变的采样率。函数的具体实现过程为：先通过resample函数更改采样率，使基频改变；然后通过一系列处理，如时长整合、帧移、帧加窗等，将语音文件恢复原来的时长，并在此过程中实现音调的升高或降低。函数的输出参数Y为处理后的语音数据。

相关问题

for i = 1:fn % 提取当前帧 current_frame = y(:,i); % 计算当前帧的 Stockwell 变换，将频率范围限制在 0 到 4000 Hz [st_matrix, ~,~] = st(current_frame,0,fs/2,fs,1); % 将当前帧的 Stockwell 变换结果存储到 st_matrices st_matrices{i} = st_matrix; b = abs(st_matrix); % 计算帧的能量 frame_energy = sum(b.^2); if frame_energy > energy_threshold % 寻找模值最大的位置 [~, max_peak_idx] = max(b); max_peak_idx = max_peak_idx(1); % 计算基频 pitch_frequency = fs /max_peak_idx; if pitch_frequency > 1000 || pitch_frequency < 70 pitch_frequencies(i)=0; continue; end % 估计基音周期 pitch_period = 1/pitch_frequency; % 存储基音周期和基频 pitch_periods(i) = pitch_period; pitch_frequencies(i) = pitch_frequency; end end优化计算基频的代码

可以使用自相关函数来进行基频的估计，具体实现可以将信号进行自相关，然后找到自相关函数的第一个峰值，该峰值对应的位置即为基音周期，基音频率即为采样率除以基音周期。

下面是使用自相关函数进行基频估计的代码示例：

for i = 1:fn
    % 提取当前帧
    current_frame = y(:,i);
    
    % 计算自相关函数
    autocorr_values = xcorr(current_frame);
    
    % 找到自相关函数的第一个峰值
    [~, max_peak_idx] = max(autocorr_values);
    pitch_period = max_peak_idx - 1;
    
    % 计算基频
    pitch_frequency = fs / pitch_period;
    if pitch_frequency > 1000 || pitch_frequency < 70
        pitch_frequencies(i) = 0;
        continue;
    end
    
    % 存储基音周期和基频
    pitch_periods(i) = pitch_period;
    pitch_frequencies(i) = pitch_frequency;
end

这样的实现可以大大减少计算量，提高基频估计的效率。

% 读取音频文件filename = 'example.aac';[x,fs] = audioread(filename);% 基频提取[pitch,~,~] = pitch(x,fs);% 共振峰提取order = 12; % LPC阶数[~,lpcResidual,a] = lpcauto(x,order);[~,f] = rceps(lpcResidual); % 反离散余弦变换f = f(1:end-1); % 去掉第一个点，因为它是无限远处的值% 绘制基频和共振峰图像t = (0:length(x)-1)/fs;figure;subplot(2,1,1);plot(t,pitch);xlabel('Time (s)');ylabel('Pitch (Hz)');title('Pitch Contour');subplot(2,1,2);plot(fs*(0:length(f)-1)/length(f),f);xlabel('Frequency (Hz)');ylabel('Magnitude (dB)');title('Resonant Frequencies');出错 untitled2 (第 4 行) [pitch,~,~] = pitch(x,fs); untitled2 调用 "varargout" 时，未对一个或多个输出参数赋值。 出错 untitled2 (第 4 行) [pitch,~,~] = pitch(x,fs);请修改这些错误

这段代码中出错的原因是pitch函数的输出参数没有被正确地赋值。pitch函数的输出参数有三个，分别是基频、每一帧的自相关函数以及每一帧的自相关函数峰值。因此，应该修改为以下代码：

[pitch,~,~] = pitch(x,fs,'WindowLength',round(0.03*fs),'OverlapLength',round(0.02*fs));

其中，'WindowLength'和'OverlapLength'是pitch函数的参数，用于控制分帧的窗口长度和重叠长度。这里使用了默认值，即窗口长度为30ms，重叠长度为20ms。