Wednesday, 20 November 2013

How to handles Text file, Excel file and Audio file in MATLAB?



AIM: Study and Implementation of file handling
            1. Text files handling
            2. Excel files handling
3. Audio file handling

THEORY:
1. Text files Handling:
Generally we use text files and for doing various documents. We can directly read text files in Matlab.
Syntax:


For reading text file:
Fid = fopen (‘Text file name.txt’, ’r’);
Var = fscanf (Fid,’%c or %d’);
Fclose (Fid)
For Writing text file:
Var = ‘Any text Matter’;
Fid = fopen (‘Text file name.txt’, ’w’);
fprintf (Fid,’%c or %d’,var);
Fclose (Fid)

2. Excel files Handling:

Excel file consist of cells we can directly access that cells for doing various operations.
Syntax:


For reading file:
[num, txt] = xlsread(‘excel file name.xlsx’);
For Writing file:
Var =’Text matter’;
Xlswrite(Var)





3. Audio files Handling

Audio file reading in Matlab is interesting process. Generally wave file are easily readable in Matlab. So aim of this experiments is
1. How to read audio file in Matlab?
2. How to play audio files in Matlab?
3. How to write audio files in Matlab?

1. Reading Audio file:
Syntax:


y = wavread(filename)
[y, Fs, nbits] = wavread(filename)
[...] = wavread(filename, N)
[...] = wavread(filename,[N1 N2])
y = wavread(filename, fmt)
siz = wavread(filename,'size')
[y, fs, nbits, opts] = wavread(...)

Description:
y = wavread(filename) loads a WAVE file specified by filename, returning the sampled data in y. The filename input is a string enclosed in single quotes. The .wav extension is appended if no extension is given.
[y, Fs, nbits] = wavread(filename) returns the sample rate (Fs) in Hertz and the number of bits per sample (nbits) used to encode the data in the file.
[...] = wavread(filename, N) returns only the first N samples from each channel in the file.
[...] = wavread(filename,[N1 N2]) returns only samples N1 through N2 from each channel in the file.
y = wavread(filename, fmt) specifies the data type format of y used to represent samples read from the file. fmt can be either of the following values.

2. Playing Audio files:
Syntax:
wavplay(y,Fs)
wavplay(...,'mode')

Description:
wavplay(y,Fs) plays the audio signal stored in the vector y on a PC-based audio output device. You specify the audio signal sampling rate with the integer Fs in samples per second. The default value for Fs is 11025 Hz (samples per second). wavplay supports only 1- or 2-channel (mono or stereo) audio signals.
wavplay(...,'mode') specifies how wavplay interacts with the command line, according to the string 'mode'

3. Writing Audio file:
Syntax:
wavwrite(y,filename)
wavwrite(y,Fs,filename)
wavwrite(y,Fs,N,filename)

Description:
wavwrite(y,filename) writes the data stored in the variable y to a WAVE file called filename. The filename input is a string enclosed in single quotes. The data has a sample rate of 8000 Hz and is assumed to be 16-bit. Each column of the data represents a separate channel. Therefore, stereo data should be specified as a matrix with two columns.
wavwrite(y,Fs,filename) writes the data stored in the variable y to a WAVE file called filename. The data has a sample rate of Fs Hz and is assumed to be 16-bit.
wavwrite(y,Fs,N,filename) writes the data stored in the variable y to a WAVE file called filename. The data has a sample rate of Fs Hz and is N-bit, where N is 8, 16, 24, or 32.

PROCEDURE:
1. First create one text and one excel file in current directory.
2. Read that text and excel files in Matlab using above syntax.
3. For writing purpose create variables which contains some text and use that text to writing purpose using above syntax.

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