2007-05-14 09:55:24 +00:00
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML>
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<HEAD>
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<TITLE>
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2009-12-02 09:23:51 +00:00
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The libsndfile API
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2007-05-14 09:55:24 +00:00
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</TITLE>
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2004-02-13 11:55:42 +00:00
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<META NAME="Author" CONTENT="Erik de Castro Lopo (erikd AT mega-nerd DOT com)">
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2007-05-14 09:55:24 +00:00
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<META NAME="Description" CONTENT="The libsndfile API.">
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<META NAME="Keywords" CONTENT="WAV AIFF AU libsndfile sound audio dsp Linux">
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2009-11-30 08:00:42 +00:00
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<LINK REL="stylesheet" HREF="libsndfile.css" TYPE="text/css" MEDIA="all">
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<LINK REL="stylesheet" HREF="print.css" TYPE="text/css" MEDIA="print">
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2007-05-14 09:55:24 +00:00
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</HEAD>
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2004-04-25 13:09:52 +00:00
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<BODY>
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2007-05-14 09:55:24 +00:00
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<BR>
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<H1><B>libsndfile</B></H1>
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<P>
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2004-06-21 22:49:08 +00:00
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Libsndfile is a library designed to allow the reading and writing of many
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different sampled sound file formats (such as MS Windows WAV and the Apple/SGI
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AIFF format) through one standard library interface.
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2007-05-14 09:55:24 +00:00
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</P>
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<!-- pepper -->
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<P>
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2004-02-14 03:02:56 +00:00
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During read and write operations, formats are seamlessly converted between the
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format the application program has requested or supplied and the file's data
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format. The application programmer can remain blissfully unaware of issues
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such as file endian-ness and data format. See <A HREF="#note1">Note 1</A> and
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2004-09-22 08:03:38 +00:00
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<A HREF="#note2">Note 2</A>.
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</P>
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<!-- pepper -->
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<P>
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2004-06-21 22:49:08 +00:00
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Every effort is made to keep these documents up-to-date, error free and
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unambiguous.
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However, since maintaining the documentation is the least fun part of working
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2014-07-01 20:33:05 +00:00
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on libsndfile, these docs can and do fall behind the behaviour of the library.
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2010-01-07 10:04:35 +00:00
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If any errors, omissions or ambiguities are found, please notify me (erikd)
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at mega-nerd dot com.
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</P>
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<!-- pepper -->
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2009-03-19 09:36:54 +00:00
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<P>
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To supplement this reference documentation, there are simple example programs
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included in the source code tarball.
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The test suite which is also part of the source code tarball is also a good
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place to look for the correct usage of the library functions.
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</P>
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<!-- pepper -->
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<P>
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<B> Finally, if you think there is some feature missing from libsndfile, check that
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it isn't already implemented (and documented)
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<A HREF="command.html">here</A>.
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</B>
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</P>
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2009-12-02 09:23:51 +00:00
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<H2><B>Synopsis</B></H2>
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<P>
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2005-11-13 11:07:52 +00:00
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The functions of libsndfile are defined as follows:
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</P>
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<!-- pepper -->
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<PRE>
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#include <stdio.h>
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#include <sndfile.h>
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SNDFILE* <A HREF="#open">sf_open</A> (const char *path, int mode, SF_INFO *sfinfo) ;
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SNDFILE* <A HREF="#open">sf_wchar_open</A> (LPCWSTR wpath, int mode, SF_INFO *sfinfo) ;
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SNDFILE* <A HREF="#open_fd">sf_open_fd</A> (int fd, int mode, SF_INFO *sfinfo, int close_desc) ;
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2011-03-15 09:55:20 +00:00
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SNDFILE* <A HREF="#open_virtual">sf_open_virtual</A> (SF_VIRTUAL_IO *sfvirtual, int mode, SF_INFO *sfinfo, void *user_data) ;
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int <A HREF="#check">sf_format_check</A> (const SF_INFO *info) ;
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sf_count_t <A HREF="#seek">sf_seek</A> (SNDFILE *sndfile, sf_count_t frames, int whence) ;
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2008-05-10 09:19:06 +00:00
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int <A HREF="command.html">sf_command</A> (SNDFILE *sndfile, int cmd, void *data, int datasize) ;
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int <A HREF="#error">sf_error</A> (SNDFILE *sndfile) ;
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const char* <A HREF="#error">sf_strerror</A> (SNDFILE *sndfile) ;
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const char* <A HREF="#error">sf_error_number</A> (int errnum) ;
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int <A HREF="#error">sf_perror</A> (SNDFILE *sndfile) ;
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int <A HREF="#error">sf_error_str</A> (SNDFILE *sndfile, char* str, size_t len) ;
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int <A HREF="#close">sf_close</A> (SNDFILE *sndfile) ;
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2005-07-31 00:40:59 +00:00
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void <A HREF="#write_sync">sf_write_sync</A> (SNDFILE *sndfile) ;
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sf_count_t <A HREF="#read">sf_read_short</A> (SNDFILE *sndfile, short *ptr, sf_count_t items) ;
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sf_count_t <A HREF="#read">sf_read_int</A> (SNDFILE *sndfile, int *ptr, sf_count_t items) ;
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sf_count_t <A HREF="#read">sf_read_float</A> (SNDFILE *sndfile, float *ptr, sf_count_t items) ;
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sf_count_t <A HREF="#read">sf_read_double</A> (SNDFILE *sndfile, double *ptr, sf_count_t items) ;
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sf_count_t <A HREF="#readf">sf_readf_short</A> (SNDFILE *sndfile, short *ptr, sf_count_t frames) ;
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sf_count_t <A HREF="#readf">sf_readf_int</A> (SNDFILE *sndfile, int *ptr, sf_count_t frames) ;
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sf_count_t <A HREF="#readf">sf_readf_float</A> (SNDFILE *sndfile, float *ptr, sf_count_t frames) ;
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sf_count_t <A HREF="#readf">sf_readf_double</A> (SNDFILE *sndfile, double *ptr, sf_count_t frames) ;
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sf_count_t <A HREF="#write">sf_write_short</A> (SNDFILE *sndfile, short *ptr, sf_count_t items) ;
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sf_count_t <A HREF="#write">sf_write_int</A> (SNDFILE *sndfile, int *ptr, sf_count_t items) ;
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sf_count_t <A HREF="#write">sf_write_float</A> (SNDFILE *sndfile, float *ptr, sf_count_t items) ;
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sf_count_t <A HREF="#write">sf_write_double</A> (SNDFILE *sndfile, double *ptr, sf_count_t items) ;
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sf_count_t <A HREF="#writef">sf_writef_short</A> (SNDFILE *sndfile, short *ptr, sf_count_t frames) ;
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sf_count_t <A HREF="#writef">sf_writef_int</A> (SNDFILE *sndfile, int *ptr, sf_count_t frames) ;
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sf_count_t <A HREF="#writef">sf_writef_float</A> (SNDFILE *sndfile, float *ptr, sf_count_t frames) ;
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sf_count_t <A HREF="#writef">sf_writef_double</A> (SNDFILE *sndfile, double *ptr, sf_count_t frames) ;
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sf_count_t <A HREF="#raw">sf_read_raw</A> (SNDFILE *sndfile, void *ptr, sf_count_t bytes) ;
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sf_count_t <A HREF="#raw">sf_write_raw</A> (SNDFILE *sndfile, void *ptr, sf_count_t bytes) ;
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const char* <A HREF="#string">sf_get_string</A> (SNDFILE *sndfile, int str_type) ;
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int <A HREF="#string">sf_set_string</A> (SNDFILE *sndfile, int str_type, const char* str) ;
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2020-08-23 06:27:58 +00:00
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const char* <A HREF="#version_string">sf_set_string</A> (void) ;
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int <A HREF="#current_byterate">sf_current_byterate</A> (SNDFILE *sndfile) ;
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int <A HREF="#set_chunk">sf_set_chunk</A> (SNDFILE * sndfile, const SF_CHUNK_INFO * chunk_info) ;
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SF_CHUNK_ITERATOR * <A HREF="#get_chunk_iterator">sf_get_chunk_iterator</A> (SNDFILE * sndfile, const SF_CHUNK_INFO * chunk_info) ;
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SF_CHUNK_ITERATOR * <A HREF="#next_chunk_iterator">sf_next_chunk_iterator</A> (SF_CHUNK_ITERATOR * iterator) ;
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int <A HREF="#get_chunk_size">sf_get_chunk_size</A> (const SF_CHUNK_ITERATOR * it, SF_CHUNK_INFO * chunk_info) ;
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int <A HREF="#get_chunk_data">sf_get_chunk_data</A> (const SF_CHUNK_ITERATOR * it, SF_CHUNK_INFO * chunk_info) ;
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</PRE>
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<!-- pepper -->
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<P>
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SNDFILE* is an anonymous pointer to data which is private to the library.
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</P>
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<A NAME="open"></A>
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<H2><B>File Open Function</B></H2>
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<PRE>
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SNDFILE* sf_open (const char *path, int mode, SF_INFO *sfinfo) ;
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</PRE>
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2015-03-17 08:56:59 +00:00
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<P>
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The sf_open() function opens the sound file at the specified path.
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The filename is byte encoded, but may be utf-8 on Linux, while on Mac OS X it
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will use the filesystem character set.
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On Windows, there is also a Windows specific sf_wchar_open() that takes a
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UTF16_BE encoded filename.
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</P>
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<PRE>
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SNDFILE* sf_wchar_open (LPCWSTR wpath, int mode, SF_INFO *sfinfo) ;
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</PRE>
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2007-05-14 09:55:24 +00:00
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<P>
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The SF_INFO structure is for passing data between the calling function and the library
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when opening a file for reading or writing. It is defined in sndfile.h as follows:
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</P>
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<!-- pepper -->
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<PRE>
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typedef struct
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{ sf_count_t frames ; /* Used to be called samples. */
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int samplerate ;
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int channels ;
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int format ;
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int sections ;
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int seekable ;
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} SF_INFO ;
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</PRE>
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<P>
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The mode parameter for this function can be any one of the following three values:
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</P>
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<!-- pepper -->
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<PRE>
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SFM_READ - read only mode
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SFM_WRITE - write only mode
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SFM_RDWR - read/write mode
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</PRE>
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<P>
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When opening a file for read, the <b>format</B> field should be set to zero before
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calling sf_open().
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The only exception to this is the case of RAW files where the caller has to set
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the samplerate, channels and format fields to valid values.
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All other fields of the structure are filled in by the library.
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</P>
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<!-- pepper -->
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<P>
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When opening a file for write, the caller must fill in structure members samplerate,
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channels, and format.
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</P>
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<!-- pepper -->
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<P>
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2004-06-21 22:49:08 +00:00
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The format field in the above SF_INFO structure is made up of the bit-wise OR of a
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major format type (values between 0x10000 and 0x08000000), a minor format type
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(with values less than 0x10000) and an optional endian-ness value.
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The currently understood formats are listed in sndfile.h as follows and also include
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bitmasks for separating major and minor file types.
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Not all combinations of endian-ness and major and minor file types are valid.
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</P>
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<!-- pepper -->
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<PRE>
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enum
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{ /* Major formats. */
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SF_FORMAT_WAV = 0x010000, /* Microsoft WAV format (little endian). */
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SF_FORMAT_AIFF = 0x020000, /* Apple/SGI AIFF format (big endian). */
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SF_FORMAT_AU = 0x030000, /* Sun/NeXT AU format (big endian). */
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SF_FORMAT_RAW = 0x040000, /* RAW PCM data. */
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SF_FORMAT_PAF = 0x050000, /* Ensoniq PARIS file format. */
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SF_FORMAT_SVX = 0x060000, /* Amiga IFF / SVX8 / SV16 format. */
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SF_FORMAT_NIST = 0x070000, /* Sphere NIST format. */
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SF_FORMAT_VOC = 0x080000, /* VOC files. */
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SF_FORMAT_IRCAM = 0x0A0000, /* Berkeley/IRCAM/CARL */
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SF_FORMAT_W64 = 0x0B0000, /* Sonic Foundry's 64 bit RIFF/WAV */
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SF_FORMAT_MAT4 = 0x0C0000, /* Matlab (tm) V4.2 / GNU Octave 2.0 */
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SF_FORMAT_MAT5 = 0x0D0000, /* Matlab (tm) V5.0 / GNU Octave 2.1 */
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SF_FORMAT_PVF = 0x0E0000, /* Portable Voice Format */
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SF_FORMAT_XI = 0x0F0000, /* Fasttracker 2 Extended Instrument */
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SF_FORMAT_HTK = 0x100000, /* HMM Tool Kit format */
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SF_FORMAT_SDS = 0x110000, /* Midi Sample Dump Standard */
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SF_FORMAT_AVR = 0x120000, /* Audio Visual Research */
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SF_FORMAT_WAVEX = 0x130000, /* MS WAVE with WAVEFORMATEX */
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SF_FORMAT_SD2 = 0x160000, /* Sound Designer 2 */
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SF_FORMAT_FLAC = 0x170000, /* FLAC lossless file format */
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SF_FORMAT_CAF = 0x180000, /* Core Audio File format */
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SF_FORMAT_WVE = 0x190000, /* Psion WVE format */
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SF_FORMAT_OGG = 0x200000, /* Xiph OGG container */
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SF_FORMAT_MPC2K = 0x210000, /* Akai MPC 2000 sampler */
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SF_FORMAT_RF64 = 0x220000, /* RF64 WAV file */
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/* Subtypes from here on. */
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SF_FORMAT_PCM_S8 = 0x0001, /* Signed 8 bit data */
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SF_FORMAT_PCM_16 = 0x0002, /* Signed 16 bit data */
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SF_FORMAT_PCM_24 = 0x0003, /* Signed 24 bit data */
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SF_FORMAT_PCM_32 = 0x0004, /* Signed 32 bit data */
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SF_FORMAT_PCM_U8 = 0x0005, /* Unsigned 8 bit data (WAV and RAW only) */
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SF_FORMAT_FLOAT = 0x0006, /* 32 bit float data */
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SF_FORMAT_DOUBLE = 0x0007, /* 64 bit float data */
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SF_FORMAT_ULAW = 0x0010, /* U-Law encoded. */
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SF_FORMAT_ALAW = 0x0011, /* A-Law encoded. */
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SF_FORMAT_IMA_ADPCM = 0x0012, /* IMA ADPCM. */
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|
|
SF_FORMAT_MS_ADPCM = 0x0013, /* Microsoft ADPCM. */
|
|
|
|
|
|
|
|
|
|
SF_FORMAT_GSM610 = 0x0020, /* GSM 6.10 encoding. */
|
2020-08-04 11:52:58 +00:00
|
|
|
SF_FORMAT_VOX_ADPCM = 0x0021, /* OKI / Dialogix ADPCM */
|
|
|
|
|
|
|
|
|
|
SF_FORMAT_NMS_ADPCM_16 = 0x0022, /* 16kbs NMS G721-variant encoding. */
|
|
|
|
|
SF_FORMAT_NMS_ADPCM_24 = 0x0023, /* 24kbs NMS G721-variant encoding. */
|
|
|
|
|
SF_FORMAT_NMS_ADPCM_32 = 0x0024, /* 32kbs NMS G721-variant encoding. */
|
2004-06-21 22:49:08 +00:00
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
SF_FORMAT_G721_32 = 0x0030, /* 32kbs G721 ADPCM encoding. */
|
|
|
|
|
SF_FORMAT_G723_24 = 0x0031, /* 24kbs G723 ADPCM encoding. */
|
|
|
|
|
SF_FORMAT_G723_40 = 0x0032, /* 40kbs G723 ADPCM encoding. */
|
2004-06-21 22:49:08 +00:00
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
SF_FORMAT_DWVW_12 = 0x0040, /* 12 bit Delta Width Variable Word encoding. */
|
|
|
|
|
SF_FORMAT_DWVW_16 = 0x0041, /* 16 bit Delta Width Variable Word encoding. */
|
|
|
|
|
SF_FORMAT_DWVW_24 = 0x0042, /* 24 bit Delta Width Variable Word encoding. */
|
|
|
|
|
SF_FORMAT_DWVW_N = 0x0043, /* N bit Delta Width Variable Word encoding. */
|
2004-06-21 22:49:08 +00:00
|
|
|
|
2005-07-13 02:48:52 +00:00
|
|
|
SF_FORMAT_DPCM_8 = 0x0050, /* 8 bit differential PCM (XI only) */
|
|
|
|
|
SF_FORMAT_DPCM_16 = 0x0051, /* 16 bit differential PCM (XI only) */
|
|
|
|
|
|
2010-10-10 03:13:39 +00:00
|
|
|
SF_FORMAT_VORBIS = 0x0060, /* Xiph Vorbis encoding. */
|
2020-08-04 11:52:58 +00:00
|
|
|
SF_FORMAT_OPUS = 0x0064, /* Xiph/Skype Opus encoding. */
|
|
|
|
|
|
|
|
|
|
SF_FORMAT_ALAC_16 = 0x0070, /* Apple Lossless Audio Codec (16 bit). */
|
|
|
|
|
SF_FORMAT_ALAC_20 = 0x0071, /* Apple Lossless Audio Codec (20 bit). */
|
|
|
|
|
SF_FORMAT_ALAC_24 = 0x0072, /* Apple Lossless Audio Codec (24 bit). */
|
|
|
|
|
SF_FORMAT_ALAC_32 = 0x0073, /* Apple Lossless Audio Codec (32 bit). */
|
2010-10-10 03:13:39 +00:00
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
/* Endian-ness options. */
|
2004-06-21 22:49:08 +00:00
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
SF_ENDIAN_FILE = 0x00000000, /* Default file endian-ness. */
|
|
|
|
|
SF_ENDIAN_LITTLE = 0x10000000, /* Force little endian-ness. */
|
|
|
|
|
SF_ENDIAN_BIG = 0x20000000, /* Force big endian-ness. */
|
|
|
|
|
SF_ENDIAN_CPU = 0x30000000, /* Force CPU endian-ness. */
|
2004-06-21 22:49:08 +00:00
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
SF_FORMAT_SUBMASK = 0x0000FFFF,
|
|
|
|
|
SF_FORMAT_TYPEMASK = 0x0FFF0000,
|
|
|
|
|
SF_FORMAT_ENDMASK = 0x30000000
|
|
|
|
|
} ;
|
|
|
|
|
</PRE>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
|
|
|
|
Every call to sf_open() should be matched with a call to sf_close() to free up
|
2004-02-14 03:02:56 +00:00
|
|
|
memory allocated during the call to sf_open().
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
2009-12-02 09:23:51 +00:00
|
|
|
On success, the sf_open function returns a non-NULL pointer which should be
|
2004-06-21 22:49:08 +00:00
|
|
|
passed as the first parameter to all subsequent libsndfile calls dealing with
|
2007-05-14 09:55:24 +00:00
|
|
|
that audio file.
|
2004-02-14 03:02:56 +00:00
|
|
|
On fail, the sf_open function returns a NULL pointer.
|
2010-11-11 09:02:14 +00:00
|
|
|
An explanation of the error can obtained by passing NULL to
|
|
|
|
|
<A HREF="#error">sf_strerror</A>.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<A NAME="open_fd"></A>
|
|
|
|
|
<H3><B>File Descriptor Open</B></H3>
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
SNDFILE* sf_open_fd (int fd, int mode, SF_INFO *sfinfo, int close_desc) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
2010-05-04 09:36:21 +00:00
|
|
|
<P>
|
|
|
|
|
<b>Note:</b> On Microsoft Windows, this function does not work if the
|
|
|
|
|
application and the libsndfile DLL are linked to different versions of the
|
|
|
|
|
Microsoft C runtime DLL.
|
|
|
|
|
</P>
|
2007-05-14 09:55:24 +00:00
|
|
|
<P>
|
2004-06-21 22:49:08 +00:00
|
|
|
The second open function takes a file descriptor of a file that has already been
|
|
|
|
|
opened.
|
|
|
|
|
Care should be taken to ensure that the mode of the file represented by the
|
2007-05-14 09:55:24 +00:00
|
|
|
descriptor matches the mode argument.
|
|
|
|
|
This function is useful in the following circumstances:
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<UL>
|
|
|
|
|
<LI>Opening temporary files securely (ie use the tmpfile() to return a
|
|
|
|
|
FILE* pointer and then using fileno() to retrieve the file descriptor
|
|
|
|
|
which is then passed to libsndfile).
|
|
|
|
|
<LI>Opening files with file names using OS specific character encodings
|
|
|
|
|
and then passing the file descriptor to sf_open_fd().
|
2004-06-21 22:49:08 +00:00
|
|
|
<LI>Opening sound files embedded within larger files.
|
2007-05-14 09:55:24 +00:00
|
|
|
<A HREF="embedded_files.html">More info</A>.
|
|
|
|
|
</UL>
|
|
|
|
|
|
|
|
|
|
<P>
|
|
|
|
|
Every call to sf_open_fd() should be matched with a call to sf_close() to free up
|
2020-09-07 14:27:13 +00:00
|
|
|
memory allocated during the call to sf_open_fd().
|
2004-06-01 11:15:25 +00:00
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>
|
|
|
|
|
When sf_close() is called, the file descriptor is only closed if the <B>close_desc</B>
|
|
|
|
|
parameter was TRUE when the sf_open_fd() function was called.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>
|
2009-12-02 09:23:51 +00:00
|
|
|
On success, the sf_open_fd function returns a non-NULL pointer which should be
|
2004-06-21 22:49:08 +00:00
|
|
|
passed as the first parameter to all subsequent libsndfile calls dealing with
|
2007-05-14 09:55:24 +00:00
|
|
|
that audio file.
|
2004-02-14 03:02:56 +00:00
|
|
|
On fail, the sf_open_fd function returns a NULL pointer.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
2011-03-15 09:55:20 +00:00
|
|
|
<A NAME="open_virtual"></A>
|
|
|
|
|
<h3><b>Virtual File Open Function</b></h3>
|
|
|
|
|
<pre>
|
|
|
|
|
SNDFILE* sf_open_virtual (SF_VIRTUAL_IO *sfvirtual, int mode, SF_INFO *sfinfo, void *user_data) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Opens a soundfile from a virtual file I/O context which is provided
|
|
|
|
|
by the caller. This is usually used to interface libsndfile to a stream or buffer
|
|
|
|
|
based system. Apart from the sfvirtual and the user_data parameters this function behaves
|
|
|
|
|
like <a href="#open">sf_open</a>.
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
<pre>
|
|
|
|
|
typedef struct
|
|
|
|
|
{ sf_vio_get_filelen get_filelen ;
|
|
|
|
|
sf_vio_seek seek ;
|
|
|
|
|
sf_vio_read read ;
|
|
|
|
|
sf_vio_write write ;
|
|
|
|
|
sf_vio_tell tell ;
|
|
|
|
|
} SF_VIRTUAL_IO ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Libsndfile calls the callbacks provided by the SF_VIRTUAL_IO structure when opening, reading
|
|
|
|
|
and writing to the virtual file context. The user_data pointer is a user defined context which
|
|
|
|
|
will be available in the callbacks.
|
|
|
|
|
</p>
|
|
|
|
|
<pre>
|
|
|
|
|
typedef sf_count_t (*sf_vio_get_filelen) (void *user_data) ;
|
|
|
|
|
typedef sf_count_t (*sf_vio_seek) (sf_count_t offset, int whence, void *user_data) ;
|
|
|
|
|
typedef sf_count_t (*sf_vio_read) (void *ptr, sf_count_t count, void *user_data) ;
|
|
|
|
|
typedef sf_count_t (*sf_vio_write) (const void *ptr, sf_count_t count, void *user_data) ;
|
|
|
|
|
typedef sf_count_t (*sf_vio_tell) (void *user_data) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<h4>sf_vio_get_filelen</h4>
|
|
|
|
|
<pre>
|
|
|
|
|
typedef sf_count_t (*sf_vio_get_filelen) (void *user_data) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
The virtual file contex must return the length of the virtual file in bytes.<br>
|
|
|
|
|
</p>
|
|
|
|
|
<h4>sf_vio_seek</h4>
|
|
|
|
|
<pre>
|
|
|
|
|
typedef sf_count_t (*sf_vio_seek) (sf_count_t offset, int whence, void *user_data) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
The virtual file context must seek to offset using the seek mode provided by whence which is one of<br>
|
|
|
|
|
</p>
|
|
|
|
|
<pre>
|
|
|
|
|
SEEK_CUR
|
|
|
|
|
SEEK_SET
|
|
|
|
|
SEEK_END
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
The return value must contain the new offset in the file.
|
|
|
|
|
</p>
|
|
|
|
|
<h4>sf_vio_read</h4>
|
|
|
|
|
<pre>
|
|
|
|
|
typedef sf_count_t (*sf_vio_read) (void *ptr, sf_count_t count, void *user_data) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
The virtual file context must copy ("read") "count" bytes into the
|
|
|
|
|
buffer provided by ptr and return the count of actually copied bytes.
|
|
|
|
|
</p>
|
|
|
|
|
<h4>sf_vio_write</h4>
|
|
|
|
|
<pre>
|
|
|
|
|
typedef sf_count_t (*sf_vio_write) (const void *ptr, sf_count_t count, void *user_data) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
The virtual file context must process "count" bytes stored in the
|
|
|
|
|
buffer passed with ptr and return the count of actually processed bytes.<br>
|
|
|
|
|
</p>
|
|
|
|
|
<h4>sf_vio_tell</h4>
|
|
|
|
|
<pre>
|
|
|
|
|
typedef sf_count_t (*sf_vio_tell) (void *user_data) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Return the current position of the virtual file context.<br>
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
<A NAME="check"></A>
|
|
|
|
|
<BR><H2><B>Format Check Function</B></H2>
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
int sf_format_check (const SF_INFO *info) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
|
|
|
|
This function allows the caller to check if a set of parameters in the SF_INFO struct
|
|
|
|
|
is valid before calling sf_open (SFM_WRITE).
|
|
|
|
|
</P>
|
|
|
|
|
<P>
|
|
|
|
|
sf_format_check returns TRUE if the parameters are valid and FALSE otherwise.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<A NAME="seek"></A>
|
|
|
|
|
<BR><H2><B>File Seek Functions</B></H2>
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
sf_count_t sf_seek (SNDFILE *sndfile, sf_count_t frames, int whence) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
|
|
|
|
<P>
|
|
|
|
|
The file seek functions work much like lseek in unistd.h with the exception that
|
2004-06-21 22:49:08 +00:00
|
|
|
the non-audio data is ignored and the seek only moves within the audio data section of
|
|
|
|
|
the file.
|
2007-05-14 09:55:24 +00:00
|
|
|
In addition, seeks are defined in number of (multichannel) frames.
|
2004-06-21 22:49:08 +00:00
|
|
|
Therefore, a seek in a stereo file from the current position forward with an offset
|
2007-05-14 09:55:24 +00:00
|
|
|
of 1 would skip forward by one sample of both channels.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>
|
|
|
|
|
like lseek(), the whence parameter can be any one of the following three values:
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
SEEK_SET - The offset is set to the start of the audio data plus offset (multichannel) frames.
|
|
|
|
|
SEEK_CUR - The offset is set to its current location plus offset (multichannel) frames.
|
|
|
|
|
SEEK_END - The offset is set to the end of the data plus offset (multichannel) frames.
|
|
|
|
|
</PRE>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
2004-06-21 22:49:08 +00:00
|
|
|
Internally, libsndfile keeps track of the read and write locations using separate
|
|
|
|
|
read and write pointers.
|
|
|
|
|
If a file has been opened with a mode of SFM_RDWR, bitwise OR-ing the standard whence
|
|
|
|
|
values above with either SFM_READ or SFM_WRITE allows the read and write pointers to
|
2007-05-14 09:55:24 +00:00
|
|
|
be modified separately.
|
|
|
|
|
If the SEEK_* values are used on their own, the read and write pointers are
|
|
|
|
|
both modified.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>
|
2004-06-21 22:49:08 +00:00
|
|
|
Note that the frames offset can be negative and in fact should be when SEEK_END is used for the
|
|
|
|
|
whence parameter.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
<P>
|
|
|
|
|
sf_seek will return the offset in (multichannel) frames from the start of the audio data
|
2004-02-14 03:02:56 +00:00
|
|
|
or -1 if an error occured (ie an attempt is made to seek beyond the start or end of the file).
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<A NAME="error"></A>
|
|
|
|
|
<H2><BR><B>Error Reporting Functions</B></H2>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
int sf_error (SNDFILE *sndfile) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
<P>
|
|
|
|
|
This function returns the current error number for the given SNDFILE.
|
|
|
|
|
The error number may be one of the following:
|
|
|
|
|
</P>
|
|
|
|
|
<PRE>
|
|
|
|
|
enum
|
|
|
|
|
{ SF_ERR_NO_ERROR = 0,
|
2005-07-13 02:48:52 +00:00
|
|
|
SF_ERR_UNRECOGNISED_FORMAT = 1,
|
|
|
|
|
SF_ERR_SYSTEM = 2,
|
|
|
|
|
SF_ERR_MALFORMED_FILE = 3,
|
|
|
|
|
SF_ERR_UNSUPPORTED_ENCODING = 4
|
2007-05-14 09:55:24 +00:00
|
|
|
} ;
|
|
|
|
|
</PRE>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
|
|
|
|
or any one of many other internal error values.
|
|
|
|
|
Applications should only test the return value against error values defined in
|
2004-06-21 22:49:08 +00:00
|
|
|
<sndfile.h> as the internal error values are subject to change at any
|
2007-05-14 09:55:24 +00:00
|
|
|
time.
|
|
|
|
|
For errors not in the above list, the function sf_error_number() can be used to
|
|
|
|
|
convert it to an error string.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
const char* sf_strerror (SNDFILE *sndfile) ;
|
|
|
|
|
const char* sf_error_number (int errnum) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
|
|
|
|
<P>
|
2004-06-21 22:49:08 +00:00
|
|
|
The error functions sf_strerror() and sf_error_number() convert the library's internal
|
|
|
|
|
error enumerations into text strings.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
<PRE>
|
|
|
|
|
int sf_perror (SNDFILE *sndfile) ;
|
|
|
|
|
int sf_error_str (SNDFILE *sndfile, char* str, size_t len) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
|
|
|
|
<P>
|
2004-02-14 03:02:56 +00:00
|
|
|
The functions sf_perror() and sf_error_str() are deprecated and will be dropped
|
2007-05-14 09:55:24 +00:00
|
|
|
from the library at some later date.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<A NAME="close"></A>
|
|
|
|
|
<H2><BR><B>File Close Function</B></H2>
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
int sf_close (SNDFILE *sndfile) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
2004-02-14 03:02:56 +00:00
|
|
|
The close function closes the file, deallocates its internal buffers and returns
|
|
|
|
|
0 on success or an error value otherwise.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
2005-07-31 00:40:59 +00:00
|
|
|
<BR>
|
|
|
|
|
|
|
|
|
|
<A NAME="write_sync"></A>
|
|
|
|
|
<H2><BR><B>Write Sync Function</B></H2>
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
void sf_write_sync (SNDFILE *sndfile) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
|
|
|
|
If the file is opened SFM_WRITE or SFM_RDWR, call the operating system's function
|
2005-08-24 22:35:33 +00:00
|
|
|
to force the writing of all file cache buffers to disk. If the file is opened
|
2005-07-31 00:40:59 +00:00
|
|
|
SFM_READ no action is taken.
|
|
|
|
|
</P>
|
|
|
|
|
<BR>
|
|
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
|
|
|
|
|
<A NAME="read"></A>
|
2016-04-11 09:52:42 +00:00
|
|
|
<H2><BR><B>File Read Functions</B></H2>
|
2007-05-14 09:55:24 +00:00
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
sf_count_t sf_read_short (SNDFILE *sndfile, short *ptr, sf_count_t items) ;
|
|
|
|
|
sf_count_t sf_read_int (SNDFILE *sndfile, int *ptr, sf_count_t items) ;
|
|
|
|
|
sf_count_t sf_read_float (SNDFILE *sndfile, float *ptr, sf_count_t items) ;
|
|
|
|
|
sf_count_t sf_read_double (SNDFILE *sndfile, double *ptr, sf_count_t items) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
|
|
|
|
<A NAME="readf"></A>
|
|
|
|
|
<PRE>
|
|
|
|
|
sf_count_t sf_readf_short (SNDFILE *sndfile, short *ptr, sf_count_t frames) ;
|
|
|
|
|
sf_count_t sf_readf_int (SNDFILE *sndfile, int *ptr, sf_count_t frames) ;
|
|
|
|
|
sf_count_t sf_readf_float (SNDFILE *sndfile, float *ptr, sf_count_t frames) ;
|
|
|
|
|
sf_count_t sf_readf_double (SNDFILE *sndfile, double *ptr, sf_count_t frames) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
2016-04-11 09:52:42 +00:00
|
|
|
The file read functions fill the array pointed to by ptr with the
|
|
|
|
|
requested number of items or frames.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
2016-04-11 09:52:42 +00:00
|
|
|
<P>
|
|
|
|
|
For the frames-count functions, the frames parameter specifies the number
|
|
|
|
|
of frames. A frame is just a block of samples, one for each
|
|
|
|
|
channel. <B>Care must be taken to ensure that there is enough space
|
|
|
|
|
in the array pointed to by ptr, to take (frames * channels) number of
|
|
|
|
|
items (shorts, ints, floats or doubles).
|
2007-05-14 09:55:24 +00:00
|
|
|
</B></P>
|
|
|
|
|
|
|
|
|
|
<P>
|
2016-04-11 09:52:42 +00:00
|
|
|
For the items-count functions, the items parameter must be an integer product
|
|
|
|
|
of the number of channels or an error will occur. Here, an item is just a
|
|
|
|
|
sample.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
2004-06-21 22:49:08 +00:00
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
<P>
|
2016-04-11 09:52:42 +00:00
|
|
|
Note: The only difference between the "items" and "frames" versions of
|
|
|
|
|
each read function is the units in which the object count is specified
|
|
|
|
|
- calling sf_readf_short with a count argument of N, on a SNDFILE with
|
|
|
|
|
C channels, is the same as calling sf_read_short with a count argument
|
|
|
|
|
of N*C. The buffer pointed to by "ptr" should be the same number of
|
|
|
|
|
bytes in each case.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
2016-04-11 09:52:42 +00:00
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
2016-04-11 09:52:42 +00:00
|
|
|
Note: The data type used by the calling program and the data format of
|
|
|
|
|
the file do not need to be the same. For instance, it is possible to
|
|
|
|
|
open a 16 bit PCM encoded WAV file and read the data using
|
|
|
|
|
sf_read_float(). The library seamlessly converts between the two
|
|
|
|
|
formats on-the-fly. See
|
2007-05-14 09:55:24 +00:00
|
|
|
<A HREF="#note1">Note 1</A>.
|
|
|
|
|
</P>
|
2016-04-11 09:52:42 +00:00
|
|
|
<!-- pepper -->
|
2007-05-14 09:55:24 +00:00
|
|
|
<P>
|
2016-04-11 09:52:42 +00:00
|
|
|
The sf_read_XXXX and sf_readf_XXXX functions return the number of
|
|
|
|
|
items or frames read, respectively. Unless the end of the file was
|
|
|
|
|
reached during the read, the return value should equal the number of
|
|
|
|
|
objects requested. Attempts to read beyond the end of the file will
|
|
|
|
|
not result in an error but will cause the read functions to return
|
|
|
|
|
less than the number of objects requested or 0 if already at the end
|
2020-08-26 07:44:46 +00:00
|
|
|
of the file. When the buffer is not is not completely filled, unused
|
|
|
|
|
buffer space is filled by zeroes.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
2004-06-21 22:49:08 +00:00
|
|
|
|
2016-04-11 09:52:42 +00:00
|
|
|
<A NAME="write"></A>
|
|
|
|
|
<H2><BR><B>File Write Functions</B></H2>
|
2007-05-14 09:55:24 +00:00
|
|
|
|
2016-04-11 09:52:42 +00:00
|
|
|
<PRE>
|
|
|
|
|
sf_count_t sf_write_short (SNDFILE *sndfile, short *ptr, sf_count_t items) ;
|
|
|
|
|
sf_count_t sf_write_int (SNDFILE *sndfile, int *ptr, sf_count_t items) ;
|
|
|
|
|
sf_count_t sf_write_float (SNDFILE *sndfile, float *ptr, sf_count_t items) ;
|
|
|
|
|
sf_count_t sf_write_double (SNDFILE *sndfile, double *ptr, sf_count_t items) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
|
|
|
|
<A NAME="writef"></A>
|
2007-05-14 09:55:24 +00:00
|
|
|
<PRE>
|
|
|
|
|
sf_count_t sf_writef_short (SNDFILE *sndfile, short *ptr, sf_count_t frames) ;
|
|
|
|
|
sf_count_t sf_writef_int (SNDFILE *sndfile, int *ptr, sf_count_t frames) ;
|
|
|
|
|
sf_count_t sf_writef_float (SNDFILE *sndfile, float *ptr, sf_count_t frames) ;
|
|
|
|
|
sf_count_t sf_writef_double (SNDFILE *sndfile, double *ptr, sf_count_t frames) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
|
|
|
|
<P>
|
2016-04-11 09:52:42 +00:00
|
|
|
The file write functions write the data in the array pointed to by ptr to the file.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
2016-04-11 09:52:42 +00:00
|
|
|
|
|
|
|
|
<P>
|
|
|
|
|
For items-count functions, the items parameter specifies the size of
|
|
|
|
|
the array and must be an integer product of the number of channels or
|
|
|
|
|
an error will occur.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>
|
|
|
|
|
For the frames-count functions, the array is expected to be large enough
|
|
|
|
|
to hold a number of items equal to the product of frames and the
|
|
|
|
|
number of channels.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>As with the read functions <A HREF="#read">above</A>, the only
|
|
|
|
|
difference in the items and frames version of each write function is
|
|
|
|
|
the units in which the buffer size is specified. Again, the data type
|
|
|
|
|
used by the calling program and the data format of the file do not
|
|
|
|
|
need to be the same (<A HREF="#note1">Note 1</A>).
|
|
|
|
|
</P>
|
|
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
<P>
|
2016-04-11 09:52:42 +00:00
|
|
|
The sf_write_XXXX and sf_writef_XXXX functions respectively return the
|
|
|
|
|
number of items or frames written (which should be the same as the
|
|
|
|
|
items or frames parameter).
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
2004-06-21 22:49:08 +00:00
|
|
|
|
2016-04-11 09:52:42 +00:00
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
<A NAME="raw"></A>
|
|
|
|
|
<H2><BR><B>Raw File Read and Write Functions</B></H2>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<PRE>
|
|
|
|
|
sf_count_t sf_read_raw (SNDFILE *sndfile, void *ptr, sf_count_t bytes) ;
|
|
|
|
|
sf_count_t sf_write_raw (SNDFILE *sndfile, void *ptr, sf_count_t bytes) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
2010-01-05 06:54:25 +00:00
|
|
|
<P>
|
|
|
|
|
<b>Note:</b> Unless you are writing an external decoder/encode that uses
|
|
|
|
|
libsndfile to handle the file headers, you should not be using these
|
|
|
|
|
functions.
|
|
|
|
|
</P>
|
|
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
<P>
|
2004-02-14 03:02:56 +00:00
|
|
|
The raw read and write functions read raw audio data from the audio file (not to be
|
2004-06-21 22:49:08 +00:00
|
|
|
confused with reading RAW header-less PCM files). The number of bytes read or written
|
|
|
|
|
must always be an integer multiple of the number of channels multiplied by the number
|
2007-05-14 09:55:24 +00:00
|
|
|
of bytes required to represent one sample from one channel.
|
|
|
|
|
</P>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
2004-06-21 22:49:08 +00:00
|
|
|
The raw read and write functions return the number of bytes read or written (which
|
|
|
|
|
should be the same as the bytes parameter).
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>
|
|
|
|
|
<B>
|
2004-06-21 22:49:08 +00:00
|
|
|
Note : The result of using of both regular reads/writes and raw reads/writes on
|
2007-05-14 09:55:24 +00:00
|
|
|
compressed file formats other than SF_FORMAT_ALAW and SF_FORMAT_ULAW is undefined.
|
|
|
|
|
</B>
|
|
|
|
|
</P>
|
|
|
|
|
|
2008-05-10 09:19:06 +00:00
|
|
|
<p>
|
|
|
|
|
See also : <a href="command.html#SFC_RAW_NEEDS_ENDSWAP">SFC_RAW_NEEDS_ENDSWAP</a>
|
|
|
|
|
</p>
|
|
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
<A NAME="string"></A>
|
|
|
|
|
<H2><BR><B>Functions for Reading and Writing String Data</B></H2>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
const char* sf_get_string (SNDFILE *sndfile, int str_type) ;
|
|
|
|
|
int sf_set_string (SNDFILE *sndfile, int str_type, const char* str) ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
|
|
|
|
<P>
|
2004-06-21 22:49:08 +00:00
|
|
|
These functions allow strings to be set on files opened for write and to be
|
2004-02-14 03:02:56 +00:00
|
|
|
retrieved from files opened for read where supported by the given file type.
|
2007-05-14 09:55:24 +00:00
|
|
|
The <B>str_type</B> parameter can be any one of the following string types:
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<PRE>
|
|
|
|
|
enum
|
|
|
|
|
{ SF_STR_TITLE,
|
|
|
|
|
SF_STR_COPYRIGHT,
|
|
|
|
|
SF_STR_SOFTWARE,
|
|
|
|
|
SF_STR_ARTIST,
|
|
|
|
|
SF_STR_COMMENT,
|
2011-06-23 09:34:33 +00:00
|
|
|
SF_STR_DATE,
|
|
|
|
|
SF_STR_ALBUM,
|
|
|
|
|
SF_STR_LICENSE,
|
|
|
|
|
SF_STR_TRACKNUMBER,
|
|
|
|
|
SF_STR_GENRE
|
2007-05-14 09:55:24 +00:00
|
|
|
} ;
|
|
|
|
|
</PRE>
|
|
|
|
|
|
|
|
|
|
<P>
|
2009-12-02 09:23:51 +00:00
|
|
|
The sf_get_string() function returns the specified string if it exists and a
|
2007-05-14 09:55:24 +00:00
|
|
|
NULL pointer otherwise.
|
2004-06-21 22:49:08 +00:00
|
|
|
In addition to the string ids above, SF_STR_FIRST (== SF_STR_TITLE) and
|
|
|
|
|
SF_STR_LAST (always the same as the highest numbers string id) are also
|
|
|
|
|
available to allow iteration over all the available string ids.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>
|
|
|
|
|
The sf_set_string() function sets the string data.
|
2004-06-21 22:49:08 +00:00
|
|
|
It returns zero on success and non-zero on error.
|
2007-05-14 09:55:24 +00:00
|
|
|
The error code can be converted to a string using sf_error_number().
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>
|
2015-03-17 08:56:59 +00:00
|
|
|
Strings passed to and retrieved from these two functions are assumed to be
|
|
|
|
|
utf-8.
|
|
|
|
|
However, while formats like Ogg/Vorbis and FLAC fully support utf-8, others
|
|
|
|
|
like WAV and AIFF officially only support ASCII.
|
|
|
|
|
Writing utf-8 strings to WAV and AIF files with libsndfile will work when read
|
|
|
|
|
back with libsndfile, but may not work with other programs.
|
|
|
|
|
</P>
|
2007-05-14 09:55:24 +00:00
|
|
|
|
2015-03-17 08:56:59 +00:00
|
|
|
<P>
|
|
|
|
|
The suggested method of dealing with tags retrived using sf_get_string() is to
|
|
|
|
|
assume they are utf-8.
|
|
|
|
|
Similarly if you have a string in some exotic format like utf-16, it should be
|
|
|
|
|
encoded to utf-8 before being written using libsndfile.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
2020-08-23 06:27:58 +00:00
|
|
|
<div id="version_string">
|
|
|
|
|
<h2>Function for retrieving library version</h2>
|
|
|
|
|
<pre>
|
|
|
|
|
const char * sf_version_string (void) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Return the library version string.
|
|
|
|
|
</p>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div id="current_byterate">
|
|
|
|
|
<h2>Function for retrieving current byterate</h2>
|
|
|
|
|
<pre>
|
|
|
|
|
int sf_current_byterate (SNDFILE *sndfile) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Return the current byterate at this point in the file. The byte rate in this
|
|
|
|
|
case is the number of bytes per second of audio data. For instance, for a
|
|
|
|
|
stereo, 18 bit PCM encoded file with an 16kHz sample rate, the byte rate
|
|
|
|
|
would be 2 (stereo) * 2 (two bytes per sample) * 16000 => 64000 bytes/sec.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
For some file formats the returned value will be accurate and exact, for some
|
|
|
|
|
it will be a close approximation, for some it will be the average bitrate for
|
|
|
|
|
the whole file and for some it will be a time varying value that was accurate
|
|
|
|
|
when the file was most recently read or written.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
To get the bitrate, multiple this value by 8.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
<code>sf_current_byterate</code> returns byte per second or -1 if byterate is
|
|
|
|
|
unknown.
|
|
|
|
|
</p>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div id="chunk">
|
|
|
|
|
<h2>Functions to get and set chunks from within a sound file</h2>
|
|
|
|
|
<p>
|
|
|
|
|
These functions allow the getting and setting of chunks within a sound file
|
|
|
|
|
(for those formats which allow it).
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
These functions fail safely. Specifically, they will not allow you to overwrite
|
|
|
|
|
existing chunks or add extra versions of format specific reserved chunks but
|
|
|
|
|
should allow you to retrieve any and all chunks (may not be implemented for
|
|
|
|
|
all chunks or all file formats).
|
|
|
|
|
</p>
|
|
|
|
|
<div id="set_chunk">
|
|
|
|
|
<h3>sf_set_chunk</h3>
|
|
|
|
|
<pre>
|
|
|
|
|
int sf_set_chunk (SNDFILE * sndfile, const SF_CHUNK_INFO * chunk_info) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Set the specified chunk info (must be done before any audio data is written
|
|
|
|
|
to the file). This will fail for format specific reserved chunks.
|
|
|
|
|
The <code>chunk_info->data</code> pointer must be valid until the file is
|
|
|
|
|
closed.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
The <code>SF_CHUNK_INFO</code> struct is documented as follows:
|
|
|
|
|
</p>
|
|
|
|
|
<pre>
|
|
|
|
|
struct SF_CHUNK_INFO
|
|
|
|
|
{ char id [64] ; /* The chunk identifier. */
|
|
|
|
|
unsigned id_size ; /* The size of the chunk identifier. */
|
|
|
|
|
unsigned datalen ; /* The size of that data. */
|
|
|
|
|
void *data ; /* Pointer to the data. */
|
|
|
|
|
} ;
|
|
|
|
|
|
|
|
|
|
typedef struct SF_CHUNK_INFO SF_CHUNK_INFO ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
<code>sf_set_chunk</code> returns <code>SF_ERR_NO_ERROR</code> on success or
|
|
|
|
|
non-zero on failure.
|
|
|
|
|
</p>
|
|
|
|
|
</div>
|
|
|
|
|
<div id="get_chunk_iterator">
|
|
|
|
|
<h3>sf_get_chunk_iterator</h3>
|
|
|
|
|
<pre>
|
|
|
|
|
SF_CHUNK_ITERATOR *
|
|
|
|
|
sf_get_chunk_iterator (SNDFILE * sndfile, const SF_CHUNK_INFO * chunk_info) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Get an iterator for all chunks matching <code>chunk_info</code>.
|
|
|
|
|
</p>
|
|
|
|
|
<p><code>SF_CHUNK_ITERATOR</code> is an opaque structure to an iterator over
|
|
|
|
|
the all chunks of a given id and defined as follows:</p>
|
|
|
|
|
<pre>
|
|
|
|
|
typedef struct SF_CHUNK_ITERATOR SF_CHUNK_ITERATOR ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>The iterator will point to the first chunk matching <code>chunk_info</code>.
|
|
|
|
|
Chunks are matching, if (<code>chunk_info->id</code>) matches the first (
|
|
|
|
|
<code>chunk_info->id_size</code>) bytes of a chunk found in the
|
|
|
|
|
<code>SNDFILE*</code> handle. If <code>chunk_info</code> is <code>NULL</code>,
|
|
|
|
|
an iterator to all chunks in the <code>SNDFILE*</code> handle is returned. The
|
|
|
|
|
values of <code>chunk_info->datalen</code> and <code>chunk_info->data</code>
|
|
|
|
|
are ignored. If no matching chunks are found in the sndfile, <code>NULL</code>
|
|
|
|
|
is returned.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
The returned iterator will stay valid until one of the following occurs:
|
|
|
|
|
</p>
|
|
|
|
|
<ol type="a">
|
|
|
|
|
<li>The sndfile is closed.</li>
|
|
|
|
|
<li>A new chunk is added using <a href="#set_chunk"><code>sf_set_chunk()</code>
|
|
|
|
|
</a>.</li>
|
|
|
|
|
<li>Another chunk iterator function is called on the same <code>SNDFILE*</code>
|
|
|
|
|
handle that causes the iterator to be modified.</li>
|
|
|
|
|
</ol>
|
|
|
|
|
<p>The memory for the iterator belongs to the SNDFILE* handle and is freed when
|
|
|
|
|
<a href="#close">sf_close()</code></a> is called.</p>
|
|
|
|
|
</div>
|
|
|
|
|
<div id="next_chunk_iterator">
|
|
|
|
|
<h3>sf_next_chunk_iterator</h3>
|
|
|
|
|
<pre>
|
|
|
|
|
sf_next_chunk_iterator (SF_CHUNK_ITERATOR * iterator) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Iterate through chunks by incrementing the iterator.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
Increments the iterator and returns a handle to the new one. After this call,
|
|
|
|
|
iterator will no longer be valid, and you must use the newly returned handle
|
|
|
|
|
from now on. The returned handle can be used to access the next chunk matching
|
|
|
|
|
the criteria as defined in <a href="#get_chunk_iterator"><code>
|
|
|
|
|
sf_get_chunk_iterator()</code></a>. If iterator points to the last chunk, this
|
|
|
|
|
will free all resources associated with iterator and return <code>NULL</code>.
|
|
|
|
|
The returned iterator will stay valid until <code>sf_get_next_chunk_iterator
|
|
|
|
|
</code> is called again, the sndfile is closed or a new chunk us added.
|
|
|
|
|
</p>
|
|
|
|
|
</div>
|
|
|
|
|
<div id="get_chunk_size">
|
|
|
|
|
<h3>sf_get_chunk_size</h3>
|
|
|
|
|
<pre>
|
|
|
|
|
int
|
|
|
|
|
sf_get_chunk_size (const SF_CHUNK_ITERATOR * it, SF_CHUNK_INFO * chunk_info) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Get the size of the specified chunk.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
If the specified chunk exists, the size will be returned in the <code>datalen
|
|
|
|
|
</code> field of the <code>SF_CHUNK_INFO</code> struct. Additionally, the id of
|
|
|
|
|
the chunk will be copied to the <code>id</code> field of the <code>
|
|
|
|
|
SF_CHUNK_INFO</code> struct and it's <code>id_size</code> field will be updated
|
|
|
|
|
accordingly.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
If the chunk doesn't exist <code>chunk_info->datalen</code> will be zero, and
|
|
|
|
|
the <code>id</code> and <code>id_size</code> fields will be undefined.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
The function will return <code>SF_ERR_NO_ERROR</code> on success or non-zero on
|
|
|
|
|
failure.
|
|
|
|
|
</p>
|
|
|
|
|
</div>
|
|
|
|
|
<div id="get_chunk_data">
|
|
|
|
|
<h3>sf_get_chunk_data</h3>
|
|
|
|
|
<pre>
|
|
|
|
|
int
|
|
|
|
|
sf_get_chunk_data (const SF_CHUNK_ITERATOR * it, SF_CHUNK_INFO * chunk_info) ;
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
Get the specified chunk data.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
If the specified chunk exists, up to <code>chunk_info->datalen</code> bytes of
|
|
|
|
|
the chunk data will be copied into the <code>chunk_info->data</code> buffer
|
|
|
|
|
(allocated by the caller) and the <code>chunk_info->datalen</code> field
|
|
|
|
|
updated to reflect the size of the data. The <code>id</code> and <code>id_size
|
|
|
|
|
</code> field will be updated according to the retrieved chunk. If the chunk
|
|
|
|
|
doesn't exist <code>chunk_info->datalen</code> will be zero, and the <code>id
|
|
|
|
|
</code> and <code>id_size</code> fields will be undefined.
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
The function will return <code>SF_ERR_NO_ERROR</code> on success or non-zero on
|
|
|
|
|
failure.
|
|
|
|
|
</p>
|
|
|
|
|
</div>
|
|
|
|
|
</div>
|
|
|
|
|
|
2007-05-14 09:55:24 +00:00
|
|
|
<HR>
|
|
|
|
|
|
|
|
|
|
<A NAME="note1"></A>
|
|
|
|
|
<H2><BR><B>Note 1</B></H2>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
2014-07-01 20:33:05 +00:00
|
|
|
When converting between integer PCM formats of differing size
|
|
|
|
|
(e.g. using sf_read_int() to read a 16 bit PCM encoded WAV file)
|
|
|
|
|
libsndfile obeys one simple rule:
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P CLASS=indent_block>
|
2004-06-21 22:49:08 +00:00
|
|
|
Whenever integer data is moved from one sized container to another sized container,
|
|
|
|
|
the most significant bit in the source container will become the most significant bit
|
|
|
|
|
in the destination container.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<P>
|
|
|
|
|
When converting between integer data and floating point data, different rules apply.
|
2004-06-21 22:49:08 +00:00
|
|
|
The default behaviour when reading floating point data (sf_read_float() or
|
|
|
|
|
sf_read_double ()) from a file with integer data is normalisation. Regardless of
|
|
|
|
|
whether data in the file is 8, 16, 24 or 32 bit wide, the data will be read as
|
2007-05-14 09:55:24 +00:00
|
|
|
floating point data in the range [-1.0, 1.0]. Similarly, data in the range [-1.0, 1.0]
|
|
|
|
|
will be written to an integer PCM file so that a data value of 1.0 will be the largest
|
|
|
|
|
allowable integer for the given bit width. This normalisation can be turned on or off
|
|
|
|
|
using the <A HREF="command.html">sf_command</A> interface.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<A NAME="note2"></A>
|
|
|
|
|
<H2><BR><B>Note 2</B></H2>
|
|
|
|
|
|
|
|
|
|
<P>
|
2004-06-21 22:49:08 +00:00
|
|
|
Reading a file containg floating point data (allowable with WAV, AIFF, AU and other
|
2005-08-24 22:35:33 +00:00
|
|
|
file formats) using integer read methods (sf_read_short() or sf_read_int()) can
|
|
|
|
|
produce unexpected results.
|
|
|
|
|
For instance the data in the file may have a maximum absolute value < 1.0 which
|
|
|
|
|
would mean that all sample values read from the file will be zero.
|
|
|
|
|
In order to read these files correctly using integer read methods, it is recommended
|
|
|
|
|
that you use the
|
|
|
|
|
<A HREF="command.html">sf_command</A>
|
2009-12-02 09:23:51 +00:00
|
|
|
interface, a command of
|
2006-02-20 02:13:10 +00:00
|
|
|
<A HREF="command.html#SFC_SET_SCALE_FLOAT_INT_READ">SFC_SET_SCALE_FLOAT_INT_READ</A>
|
2005-08-24 22:35:33 +00:00
|
|
|
and a parameter of SF_TRUE to force correct scaling.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<HR>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<P>
|
2004-06-21 22:49:08 +00:00
|
|
|
The libsndfile home page is
|
2020-10-05 07:11:47 +00:00
|
|
|
<A HREF="http://libsndfile.github.io/libsndfile/">here</A>.
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
<P>
|
2020-09-19 05:38:08 +00:00
|
|
|
Version : 1.0.30
|
2007-05-14 09:55:24 +00:00
|
|
|
</P>
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
<!-- pepper -->
|
|
|
|
|
|
|
|
|
|
</BODY>
|
|
|
|
|
</HTML>
|
