read and write data from .mat file

I have a .mat file containing matrix of size 8x3800000.

I need to read 8x980 matrix twice at a time, process it(overlap add technique of convolution) and write back the processed data into a new file.

That is, at a time my RAM should hold only 2x(8x980) data blocks.

How can I do it efficiently? Please help me with the relevant syntax.

Thank you.

Answer 1

[Wayne King]

Do you have the DSP System Toolbox? You can use dsp.MatFileReader

For example:

filename = [tempname '.mat'];  % Create variable name
originalData = rand(100,4);
save(filename,'originalData','-v7.3'); % Write to MAT file
H =  dsp.MatFileReader(filename,'VariableName',...
   'originalData','SamplesPerFrame', 25); 
Y = step(H);

Each time step() is called you get 25x4 out of the 100x4 matrix.

[zozo]

I have DSP System Toolbox but donot have dsp.MatFileReader.

[Wayne King]

This is in R2012a. Are you able to update?

[zozo]

how can I update? I have R2011b currently.

[Wayne King]

You have to contact MathWorks for that. If your version of MATLAB is on maintenance, you should be able to just download R2012a. I don't know what your licensing situation is, so contact MW.

[zozo]

How can I only write data into file sequencially after processing? For example: At first, I have two blocks of length 1024, I overlap(44 samples in head and tail) and add them, then save(write) the first 1024 in a file. Then I do the same for 2nd and 3rd blocks and save the 2nd block behind the first block (and so on..) How can I do this?