add_affix.m

国外大学的同志作出来的好程序

function [frames, frames_num]=add_affix(symbols, frame_data_len, prefix, appendix);
%To add the prefix and the appendix;
%
%assume symbols, prefix, appendix are all column vecoters.
if size(symbols, 1)>1 && size(symbols, 2)>2,
    disp('[add_affix]Only input symbols of vectors are supported.');
    return;
end

%trim the symbols
if mod(length(symbols), frame_data_len)~=0,
    tval=mod(length(symbols), frame_data_len);
    if tval<0.1*frame_data_len,
        frames_num=floor(length(symbols)/frame_data_len);
        symbols=symbols(1: frame_data_len*frames_num);
    else
        symbols=[symbols; zeros(frame_data_len-tval, 1)];
    end
end

%normalize all parts
symbols=symbols/max(abs(symbols));
prefix=prefix/max(abs(prefix));
appendix=appendix/max(abs(appendix));

%reshape the symbols into matrix
frames_num=floor(length(symbols)/frame_data_len);
frame_matrix=reshape(symbols, frame_data_len, frames_num);

%add prefix and appendix
prefix_matrix=repmat(prefix, 1, frames_num);
appendix_matrix=repmat(appendix, 1, frames_num);

frames=[prefix_matrix; frame_matrix; appendix_matrix];

%make frames a column vector
frames=frames(:);