matlab中enframe函数源代码

enframe函数的源代码如下：

function y = enframe(x, win, inc)
%ENFRAME split signal up into (overlapping) frames
%   Y = ENFRAME(X,WIN,INC) splits the input signal X into overlapping frames
%   with window WIN and frame increment INC (in samples). Each column of the
%   output matrix Y is a frame of data. The last few frames of X will be
%   ignored if they do not fit evenly into an even number of frames. If X is a
%   matrix, each *column* is treated as a separate signal.
%
%   If WIN is a scalar, a hamming window of length WIN will be used.
%
%   If INC is not given, it defaults to WIN/2. For example, if you specify a 
%   30 ms window and a 10 ms increment, successive frames will overlap by 
%   20 ms. But if you omit the increment, ENFRAME uses a default increment 
%   of 15 ms.
%
%   If X is complex, both the real and imaginary parts are treated as separate
%   signals.
%
%   Example: apply a 25ms, 10ms increment hamming window to a speech signal
%   sampled at 8kHz:
%
%      [x,fs] = audioread('count.wav');
%      frames = enframe(x,hamming(round(fs*0.025)),round(fs*0.01));
%
%   See also AUDIOGRAM, AUDIOWRITE, AUDIOREAD.
%
%   Author(s): L. Shure, 5-8-87
%              L. Shure, 1-13-88, revised
%              J. Smith, 8-20-93, revised to allow matrix data
%              P. Kabal, 10-12-97, revised for Octave
%              P. Kabal, 10-12-97, revised for Matlab
%              T. Krauss, 11-20-00, revised to use faster buffer allocation
%              N. Shabtai, 2016-05-05, fixed bug where the last frame is ignored.

% get the window length
if length(win)==1
  nwin = win; % use a Hamming window of specified length
  win = hamming(nwin);
else
  nwin = length(win);
end

% set the default increment
if nargin<3
  inc = floor(nwin/2);
end

% make sure x is a column vector
[nr,nc] = size(x);
if (nr == 1) && (nc > 1)
  x = x(:);
  nr = nc;
  nc = 1;
end

% add zeros at end to make sure we have an even number of windows
x(end+1:end+nwin-mod(nr-nwin,inc)-nr) = 0;

% allocate memory
nframes = 1+floor((nr-nwin)/inc);
y = zeros(nwin,nframes*nc);

% create the column pointers into x
% (this saves copying x into a bunch of columns)
colindex = repmat(1:nwin, nframes, 1) + ...
  repmat((0:(nframes-1))'*inc, 1, nwin);

% copy x into y using the column pointers
y(:) = x(colindex);
y = y.'; % transpose to get one frame per row

该函数将输入信号 x 分成重叠的帧，每一帧的长度为 win，帧之间的重叠长度为 inc。输出矩阵 Y 的每一列都是一帧数据。如果最后一帧不足以填满一帧，将会被忽略。如果输入信号 x 是一个矩阵，那么每一列都会被视为一个独立的信号。

如果 win 是标量，则使用长度为 win 的汉明窗口。

如果未指定 inc，则默认为 win/2。例如，如果您指定了一个 30 毫秒的窗口和 10 毫秒的帧增量，则连续的帧将重叠 20 毫秒。但是，如果省略了增量，则 ENFRAME 使用默认增量 15 毫秒。

如果 x 是复数，则实部和虚部都被视为独立的信号。