diff options
| author | Lorry <lorry@roadtrain.codethink.co.uk> | 2012-07-18 20:35:05 +0100 |
|---|---|---|
| committer | Lorry <lorry@roadtrain.codethink.co.uk> | 2012-07-18 20:35:05 +0100 |
| commit | aceb1f30497619786f1827e4c65992b890a07410 (patch) | |
| tree | ce33ac9d0d076a8ec4f993e614cf71a4d5daa7e7 /doc/octave.html | |
| download | libsndfile-aceb1f30497619786f1827e4c65992b890a07410.tar.gz | |
Tarball conversion
Diffstat (limited to 'doc/octave.html')
| -rw-r--r-- | doc/octave.html | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/doc/octave.html b/doc/octave.html new file mode 100644 index 0000000..525b7ae --- /dev/null +++ b/doc/octave.html @@ -0,0 +1,118 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<HTML> + +<HEAD> + <TITLE> + libsndfile and GNU Octave + </TITLE> + <META NAME="Author" CONTENT="Erik de Castro Lopo (erikd AT mega-nerd DOT com)"> + <LINK REL="stylesheet" HREF="libsndfile.css" TYPE="text/css" MEDIA="all"> + <LINK REL="stylesheet" HREF="print.css" TYPE="text/css" MEDIA="print"> +</HEAD> + +<BODY> + +<BR> +<H1><B>libsndfile and GNU Octave</B></H1> +<P> + <A HREF="http://www.octave.org/">GNU Octave</A> is a high-level interactive + language for numerical computations. + There are currently two development streams, a stable 2.0.X series and a + development 2.1.X series. + Octave reads and writes data in binary formats that were originally developed + for + <A HREF="http://www.mathworks.com/">MATLAB</A>. + Version 2.0.X of Octave uses binary data files compatible with MATLAB + version 4.2 while Octave 2.1.X uses binary data files compatible + with MATLAB version 5.0 as well as being able to read the older MATLAB 4.2 + format. +</P> +<P> + From version 1.0.1 of libsndfile onwards, libsndfile has the ability of reading + and writing a small subset of the binary data files used by both versions + of GNU Octave. + This gives people using GNU Octave for audio based work an easy method of + moving audio data between GNU Octave and other programs which use libsndfile. +</P> +<P> + For instance it is now possible to do the following: +</P> + + <UL> + <LI> Load a WAV file into a sound file editor such as + <A HREF="http://www.metadecks.org/software/sweep/">Sweep</A>. + <LI> Save it as a MAT4 file. + <LI> Load the data into Octave for manipulation. + <LI> Save the modified data. + <LI> Reload it in Sweep. + </UL> +<P> + Another example would be using the MAT4 or MAT5 file formats as a format which + can be easily loaded into Octave for viewing/analyzing as well as a format + which can be played with command line players such as the one included with + libsndfile. +</P> + +<H2><B>Details</B></H2> +<P> + Octave, like most programming languages, uses variables to store data, and + Octave variables can contain both arrays and matrices. + It is also able to store one or more of these variables in a file. + When reading Octave files, libsndfile expects a file to contain two + variables and their associated data. + The first variable should contain a variable holding the file sample rate + while the second variable contains the audio data. +</P> +<P> + For example, to generate a sine wave and store it as a binary file which + is compatible with libsndfile, do the following: +</P> +<PRE> + octave:1 > samplerate = 44100 ; + octave:2 > wavedata = sin ((0:1023)*2*pi/1024) ; + octave:3 > save sine.mat samplerate wavedata +</PRE> + +<P> + The process of reading and writing files compatible with libsndfile can be + made easier by use of two Octave script files : +</P> +<PRE> + octave:4 > [data fs] = sndfile_load ("sine.mat") ; + octave:5 > sndfile_save ("sine2.mat", data, fs) ; +</PRE> +<P> + In addition, libsndfile contains a command line program which which is able + to play the correct types of Octave files. + Using this command line player <B>sndfile-play</B> and a third Octave script + file allows Octave data to be played from within Octave on any of the platforms + which <B>sndfile-play</B> supports (at the moment: Linux, MacOS X, Solaris and + Win32). +</P> +<PRE> + octave:6 > sndfile_play (data, fs) ; +</PRE> +<P> + These three Octave scripts are installed automatically in Octave's site + script directory when libsndfile is installed (except on Win32) ie when + libsndfile is being installed into /usr/local, the Octave scripts will + be installed in /usr/local/share/octave/site/m/. +</P> + +<P> + There are some other Octave scripts for audio to be found + <A HREF="http://octave.sourceforge.net/index/audio.html">here</A>. +</P> + +<BR> +<!-- ========================================================================= --> + +<HR> +<P> + The libsndfile home page is here : + <A HREF="http://www.mega-nerd.com/libsndfile/"> + http://www.mega-nerd.com/libsndfile/</A>. +</P> + +</BODY> +</HTML> |