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Hi. I hope there's someone who can help me with this. I am relatively new to DSP and Matlab. I have a data sequence (essentially obtained by wavread from a speech wav file). What I need to do now is to block the data into frames of 30ms long, and then overlap them (20ms of overlap). Does anyone have any suggestion on how I should approach this?

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--- wrote: > Hi. I hope there's someone who can help me with > this. I am relatively > new to DSP and Matlab. > > I have a data sequence (essentially obtained by > wavread from a speech > wav file). What I need to do now is to block the > data into frames of > 30ms long, and then overlap them (20ms of overlap). > > Does anyone have any suggestion on how I should > approach this? > Hi, It seems that your problem is asimple one althohgh it frased in acomplicated way. I assume you havs a long sequence of data that you want to cut into equally long segments and than show it on a graph with some given overlap. Suppose the total number of data points is N and each segment is n long. The segmentation is done by: Mseg=reshape(Data,n,floor(N/n)); To plot it so that each on is starting k points after the start of the previous segment you have to make a loop. *Code* X=1:n; Q=k; % shift Col=['r','b','g','c','y','m','k'] %colors vector for k=1:floor(N/n) K=mod(k,7)+1; plot(X,Mseg(:,k),'color',Col(K)); hold on X=X+Q; end drawnow *End* Joe BSTEX - Equation viewer for Matlab http://www.geocities.com/bstex2001 __________________________________________________

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If you are using the Signal Processing Toolbox, try using BUFFER. Here is the help: >> help buffer BUFFER Buffer a signal vector into a matrix of data frames. Y = BUFFER(X,N) partitions signal vector X into nonoverlapping data segments (frames) of length N. Each data frame occupies one column in the output matrix, resulting in a matrix with N rows. Y = BUFFER(X,N,P) specifies an integer value P which controls the amount of overlap or underlap in the buffered data frames. - If P>0, there will be P samples of data from the end of one frame (column) that will be repeated at the start of the next data frame. - If P<0, the buffering operation will skip P samples of data after each frame, effectively skipping over data in X, and thus reducing the buffer "frame rate". - If empty or omitted, P is assumed to be zero (no overlap or underlap). Y = BUFFER(X,N,P,OPT) specifies an optional parameter OPT used in the case of overlap or underlap buffering. - If P>0 (overlap), OPT specifies an initial condition vector with length equal to the overlap, P. If empty or omitted, the initial condition is assumed to be zeros(P,1). Alternatively, OPT can be set to 'nodelay' which removes initial conditions from the output and starts buffering at the first data sample in X. - If P<0 (underlap), OPT specifies a scalar offset indicating the number of initial data samples in X to skip. The offset must be in the range [0, -P], where P<0. If empty or omitted, the offset is zero. Y = BUFFER(X, ...) returns a matrix of data frames, one frame per column. If X does not contain a multiple of (N-P) samples, zeros will be appended to the last frame as needed. [Y,Z] = BUFFER(X, ...) forces Y to contain only complete frames of data, and returns any remaining samples (i.e., a partial frame) in vector Z. The orientation of vector Z will be the same as X. Z will be an empty vector if the length of X is a multiple of (N-P). [Y,Z,OPT] = BUFFER(X, ...) returns an options argument OPT which can be used in the next call to BUFFER, and is primarily intended for use in continuous buffering applications. EXAMPLE: Buffering with overlap. Buffer an entire signal vector into 8-sample frames, each frame overlapping the previous one by 4 samples. x = 1:18; % Example input data to be buffered y = buffer(x, 8, 4); % Create overlapping buffer matrix EXAMPLE: Buffering with underlap. Buffer an entire signal vector into 8-sample frames, skipping 4 samples between frames. Return any partial buffer separately. x = 1:40; % Example input data to be buffered [y,z] = buffer(x, 8, -4); % Return last partial frame in z HTH, Bill D. Joe Sababa <joesababa@ya To: , hoo.com> cc: Subject: Re: [matlab] Framing and overlapping of data sequences 12/04/2001 04:25 PM --- wrote: > Hi. I hope there's someone who can help me with > this. I am relatively > new to DSP and Matlab. > > I have a data sequence (essentially obtained by > wavread from a speech > wav file). What I need to do now is to block the > data into frames of > 30ms long, and then overlap them (20ms of overlap). > > Does anyone have any suggestion on how I should > approach this? > Hi, It seems that your problem is asimple one althohgh it frased in acomplicated way. I assume you havs a long sequence of data that you want to cut into equally long segments and than show it on a graph with some given overlap. Suppose the total number of data points is N and each segment is n long. The segmentation is done by: Mseg=reshape(Data,n,floor(N/n)); To plot it so that each on is starting k points after the start of the previous segment you have to make a loop. *Code* X=1:n; Q=k; % shift Col=['r','b','g','c','y','m','k'] %colors vector for k=1:floor(N/n) K=mod(k,7)+1; plot(X,Mseg(:,k),'color',Col(K)); hold on X=X+Q; end drawnow *End* Joe BSTEX - Equation viewer for Matlab http://www.geocities.com/bstex2001 __________________________________________________ _____________________________________ /groups.php3

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