SndFile

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SndFile

SndFile – SndFile data type

Constructor

L = fopen(file-name,mode=’string’,xdr=boolean,swap=boolean)

Parameters

mode: The argument mode is a string beginning with one of the following sequences
- : open text file for reading. The stream is positioned at the beginning of the file.
- truncate file to zero length or create text file for writing. The stream is positioned at the beginning of the file.
- open for appending (writing at end of file). The file is created if it does not exist. The stream is positioned at the end of the file.
The mode string can also include the letter b as a last character. Adding the b is used if you do I/O to a binary file (but note that The b is ignored on all POSIX conforming systems, including Linux).
swap If true then byte swaping is forced when using the mget and mput functions.
xdr If true then reading and writing is used using xdr.

Description
The SndFile data type is used for file I/O operations.

Operations on SndFile objects

attributes

frames: number of frames in the sound file.
samplerate: signal sample rate.
channels: number of channels.
format: format of sound file.
sections: number of sections.
seekable: returns a boolean if the file seekable ?

methods

F.close[] closes sound file.
F.error[] gets error code of last error raised.
F.strerror[] gets error message of last error raised
F.error_number[err] get error message associated to error number.
A=F.read[n] reads n frames from sound file and returns the result in a numeric matrix of size mxn where m is the number of channels of file
F.seek[n,tag] sets the file position indicator for the stream pointed to by stream. The new position, measured in bytes, is obtained by adding offset bytes n to the position specified by tag. tag can be set to "set", or "cur", or "end", the offset is relative to the start of the file, the current position indicator, or end-of-file, respectively.
F.write[A] write data in sound file from numerical matrix A. the number of rows of A must be equal to number of channels of file.

functions

sndfile opens a sound file.
play(A,job plays a matrix assuming that the samplerate is 22050. The function must be called with job equal to 1 to initialize, to 2 to play and to 3 to close the sound channel.

Examples

rate=22050;n=3;t=linspace(0,n,n*rate); 
x1=sin(2*%pi*220*t); 
x2=sin(2*%pi*440*t); 
x3=sin(2*%pi*660*t); 
x=x1+0.5*x2+0.25*x3; 
F=sndfile('test.wav',mode='w',samplerate=22050,channels=1); 
F.write[x]; 
F.close[]; 
F=sndfile('test.wav',mode='r'); 
F.format 
F.frames