celp数字话音编码代码
时间: 2024-02-17 22:02:48 浏览: 174
CELP数字话音编码是一个相对复杂的算法,需要大量的数学和信号处理知识才能实现。以下是一个简单的基于MATLAB的CELP编码代码示例,仅供参考:
```matlab
% 读取语音信号
[x, Fs] = audioread('speech.wav');
% 设置CELP编码器参数
frame_length = 20; % 每帧长度(毫秒)
frame_shift = 10; % 帧移(毫秒)
LPC_order = 10; % 线性预测分析阶数
excitation_order = 10; % 激励码本大小
codebook_size = 1024; % 预测系数码本大小
max_iterations = 10; % 最大迭代次数
% 分帧
frame_length = round(frame_length/1000*Fs);
frame_shift = round(frame_shift/1000*Fs);
num_frames = floor((length(x)-frame_length)/frame_shift) + 1;
frames = zeros(num_frames, frame_length);
for i=1:num_frames
frames(i,:) = x((i-1)*frame_shift+1:(i-1)*frame_shift+frame_length);
end
% 初始化CELP编码器
LPC_coeffs = zeros(num_frames, LPC_order+1);
excitation_indices = zeros(num_frames, excitation_order);
codebook_indices = zeros(num_frames, frame_length);
residuals = zeros(num_frames, frame_length);
% 循环编码每一帧
for i=1:num_frames
% 线性预测分析
[LPC_coeffs(i,:), residuals(i,:)] = lpc(frames(i,:), LPC_order);
% 计算激励
excitation = zeros(1, frame_length);
for j=1:excitation_order
[~, idx] = min(sum((repmat(frames(i,:)', 1, codebook_size) ...
- repmat(LPC_coeffs(i,2:end)', 1, codebook_size) ...
.* codebook).^2));
excitation(idx) = 1;
excitation_indices(i,j) = idx;
end
% 计算预测系数
[codebook, ~] = lbg(LPC_coeffs(i,2:end)', codebook_size, max_iterations);
for j=1:frame_length
[~, idx] = min(sum((repmat(frames(i,:)', 1, codebook_size) ...
- repmat(LPC_coeffs(i,2:end)', 1, codebook_size) ...
.* codebook).^2));
codebook_indices(i,j) = idx;
end
% 合成帧
synth_frame = filter([0 -LPC_coeffs(i,2:end)], 1, excitation);
synth_frame = synth_frame + filter(1, [1 -LPC_coeffs(i,2:end)], residuals(i,:));
end
% 保存CELP编码结果
save('speech.celp', 'LPC_coeffs', 'excitation_indices', 'codebook_indices', 'residuals');
% 解码语音信号
load('speech.celp', 'LPC_coeffs', 'excitation_indices', 'codebook_indices', 'residuals');
num_frames = size(LPC_coeffs, 1);
synth_signal = zeros(1, (num_frames-1)*frame_shift+frame_length);
for i=1:num_frames
% 合成激励
excitation = zeros(1, frame_length);
for j=1:excitation_order
excitation(excitation_indices(i,j)) = 1;
end
% 合成预测系数
codebook = lbg(LPC_coeffs(i,2:end)', codebook_size, max_iterations);
for j=1:frame_length
synth_frame = filter([0 -LPC_coeffs(i,2:end)], 1, excitation(j));
synth_frame = synth_frame + filter(1, [1 -LPC_coeffs(i,2:end)], ...
codebook(:,codebook_indices(i,j))');
synth_signal((i-1)*frame_shift+1:(i-1)*frame_shift+frame_length) = ...
synth_signal((i-1)*frame_shift+1:(i-1)*frame_shift+frame_length) + synth_frame;
end
end
% 写入解码结果
audiowrite('speech_decoded.wav', synth_signal, Fs);
```
这个代码示例仅提供了一个基本的CELP编码和解码过程,实际的CELP编码器需要考虑更多的细节和优化,例如使用更高效的搜索算法和码本设计算法等。
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