+++ /dev/null
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
-<HTML>
-
-<HEAD>
- <TITLE>
- The libsndfile API
- </TITLE>
- <META NAME="Author" CONTENT="Erik de Castro Lopo (erikd AT mega-nerd DOT com)">
- <META NAME="Description" CONTENT="The libsndfile API.">
- <META NAME="Keywords" CONTENT="WAV AIFF AU libsndfile sound audio dsp Linux">
- <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</B></H1>
-<P>
- Libsndfile is a library designed to allow the reading and writing of many
- different sampled sound file formats (such as MS Windows WAV and the Apple/SGI
- AIFF format) through one standard library interface.
-</P>
-<!-- pepper -->
-<P>
- During read and write operations, formats are seamlessly converted between the
- format the application program has requested or supplied and the file's data
- format. The application programmer can remain blissfully unaware of issues
- such as file endian-ness and data format. See <A HREF="#note1">Note 1</A> and
- <A HREF="#note2">Note 2</A>.
-</P>
-<!-- pepper -->
-<P>
- Every effort is made to keep these documents up-to-date, error free and
- unambiguous.
- However, since maintaining the documentation is the least fun part of working
- on libsndfile, these docs can and do fall behind the behaviour of library.
- If any errors, omissions or ambiguities are found, please notify me (erikd)
- at mega-nerd dot com.
-</P>
-<!-- pepper -->
-<P>
- To supplement this reference documentation, there are simple example programs
- included in the source code tarball.
- The test suite which is also part of the source code tarball is also a good
- place to look for the correct usage of the library functions.
-</P>
-<!-- pepper -->
-<P>
- <B> Finally, if you think there is some feature missing from libsndfile, check that
- it isn't already implemented (and documented)
- <A HREF="command.html">here</A>.
- </B>
-</P>
-
-<H2><B>Synopsis</B></H2>
-<P>
-The functions of libsndfile are defined as follows:
-</P>
-<!-- pepper -->
-<PRE>
- #include <stdio.h>
- #include <sndfile.h>
-
- SNDFILE* <A HREF="#open">sf_open</A> (const char *path, int mode, SF_INFO *sfinfo) ;
- SNDFILE* <A HREF="#open_fd">sf_open_fd</A> (int fd, int mode, SF_INFO *sfinfo, int close_desc) ;
- SNDFILE* <A HREF="#open_virtual">sf_open_virtual</A> (SF_VIRTUAL_IO *sfvirtual, int mode, SF_INFO *sfinfo, void *user_data) ;
- int <A HREF="#check">sf_format_check</A> (const SF_INFO *info) ;
-
- sf_count_t <A HREF="#seek">sf_seek</A> (SNDFILE *sndfile, sf_count_t frames, int whence) ;
-
- int <A HREF="command.html">sf_command</A> (SNDFILE *sndfile, int cmd, void *data, int datasize) ;
-
- int <A HREF="#error">sf_error</A> (SNDFILE *sndfile) ;
- const char* <A HREF="#error">sf_strerror</A> (SNDFILE *sndfile) ;
- const char* <A HREF="#error">sf_error_number</A> (int errnum) ;
-
- int <A HREF="#error">sf_perror</A> (SNDFILE *sndfile) ;
- int <A HREF="#error">sf_error_str</A> (SNDFILE *sndfile, char* str, size_t len) ;
-
- int <A HREF="#close">sf_close</A> (SNDFILE *sndfile) ;
- void <A HREF="#write_sync">sf_write_sync</A> (SNDFILE *sndfile) ;
-
- sf_count_t <A HREF="#read">sf_read_short</A> (SNDFILE *sndfile, short *ptr, sf_count_t items) ;
- sf_count_t <A HREF="#read">sf_read_int</A> (SNDFILE *sndfile, int *ptr, sf_count_t items) ;
- sf_count_t <A HREF="#read">sf_read_float</A> (SNDFILE *sndfile, float *ptr, sf_count_t items) ;
- sf_count_t <A HREF="#read">sf_read_double</A> (SNDFILE *sndfile, double *ptr, sf_count_t items) ;
-
- sf_count_t <A HREF="#readf">sf_readf_short</A> (SNDFILE *sndfile, short *ptr, sf_count_t frames) ;
- sf_count_t <A HREF="#readf">sf_readf_int</A> (SNDFILE *sndfile, int *ptr, sf_count_t frames) ;
- sf_count_t <A HREF="#readf">sf_readf_float</A> (SNDFILE *sndfile, float *ptr, sf_count_t frames) ;
- sf_count_t <A HREF="#readf">sf_readf_double</A> (SNDFILE *sndfile, double *ptr, sf_count_t frames) ;
-
- sf_count_t <A HREF="#write">sf_write_short</A> (SNDFILE *sndfile, short *ptr, sf_count_t items) ;
- sf_count_t <A HREF="#write">sf_write_int</A> (SNDFILE *sndfile, int *ptr, sf_count_t items) ;
- sf_count_t <A HREF="#write">sf_write_float</A> (SNDFILE *sndfile, float *ptr, sf_count_t items) ;
- sf_count_t <A HREF="#write">sf_write_double</A> (SNDFILE *sndfile, double *ptr, sf_count_t items) ;
-
- sf_count_t <A HREF="#writef">sf_writef_short</A> (SNDFILE *sndfile, short *ptr, sf_count_t frames) ;
- sf_count_t <A HREF="#writef">sf_writef_int</A> (SNDFILE *sndfile, int *ptr, sf_count_t frames) ;
- sf_count_t <A HREF="#writef">sf_writef_float</A> (SNDFILE *sndfile, float *ptr, sf_count_t frames) ;
- sf_count_t <A HREF="#writef">sf_writef_double</A> (SNDFILE *sndfile, double *ptr, sf_count_t frames) ;
-
- sf_count_t <A HREF="#raw">sf_read_raw</A> (SNDFILE *sndfile, void *ptr, sf_count_t bytes) ;
- sf_count_t <A HREF="#raw">sf_write_raw</A> (SNDFILE *sndfile, void *ptr, sf_count_t bytes) ;
-
- const char* <A HREF="#string">sf_get_string</A> (SNDFILE *sndfile, int str_type) ;
- int <A HREF="#string">sf_set_string</A> (SNDFILE *sndfile, int str_type, const char* str) ;
-
-</PRE>
-<!-- pepper -->
-<P>
-SNDFILE* is an anonymous pointer to data which is private to the library.
-</P>
-
-
-<A NAME="open"></A>
-<H2><B>File Open Function</B></H2>
-
-<PRE>
- SNDFILE* sf_open (const char *path, int mode, SF_INFO *sfinfo) ;
-</PRE>
-
-<P>
-The SF_INFO structure is for passing data between the calling function and the library
-when opening a file for reading or writing. It is defined in sndfile.h as follows:
-</P>
-<!-- pepper -->
-<PRE>
- typedef struct
- { sf_count_t frames ; /* Used to be called samples. */
- int samplerate ;
- int channels ;
- int format ;
- int sections ;
- int seekable ;
- } SF_INFO ;
-</PRE>
-
-<P>
-The mode parameter for this function can be any one of the following three values:
-</P>
-<!-- pepper -->
-<PRE>
- SFM_READ - read only mode
- SFM_WRITE - write only mode
- SFM_RDWR - read/write mode
-</PRE>
-
-<P>
-When opening a file for read, the <b>format</B> field should be set to zero before
-calling sf_open().
-The only exception to this is the case of RAW files where the caller has to set
-the samplerate, channels and format fields to valid values.
-All other fields of the structure are filled in by the library.
-</P>
-<!-- pepper -->
-<P>
-When opening a file for write, the caller must fill in structure members samplerate,
-channels, and format.
-</P>
-<!-- pepper -->
-<P>
-The format field in the above SF_INFO structure is made up of the bit-wise OR of a
-major format type (values between 0x10000 and 0x08000000), a minor format type
-(with values less than 0x10000) and an optional endian-ness value.
-The currently understood formats are listed in sndfile.h as follows and also include
-bitmasks for separating major and minor file types.
-Not all combinations of endian-ness and major and minor file types are valid.
-</P>
-<!-- pepper -->
-<PRE>
- enum
- { /* Major formats. */
- SF_FORMAT_WAV = 0x010000, /* Microsoft WAV format (little endian). */
- SF_FORMAT_AIFF = 0x020000, /* Apple/SGI AIFF format (big endian). */
- SF_FORMAT_AU = 0x030000, /* Sun/NeXT AU format (big endian). */
- SF_FORMAT_RAW = 0x040000, /* RAW PCM data. */
- SF_FORMAT_PAF = 0x050000, /* Ensoniq PARIS file format. */
- SF_FORMAT_SVX = 0x060000, /* Amiga IFF / SVX8 / SV16 format. */
- SF_FORMAT_NIST = 0x070000, /* Sphere NIST format. */
- SF_FORMAT_VOC = 0x080000, /* VOC files. */
- SF_FORMAT_IRCAM = 0x0A0000, /* Berkeley/IRCAM/CARL */
- SF_FORMAT_W64 = 0x0B0000, /* Sonic Foundry's 64 bit RIFF/WAV */
- SF_FORMAT_MAT4 = 0x0C0000, /* Matlab (tm) V4.2 / GNU Octave 2.0 */
- SF_FORMAT_MAT5 = 0x0D0000, /* Matlab (tm) V5.0 / GNU Octave 2.1 */
- SF_FORMAT_PVF = 0x0E0000, /* Portable Voice Format */
- SF_FORMAT_XI = 0x0F0000, /* Fasttracker 2 Extended Instrument */
- SF_FORMAT_HTK = 0x100000, /* HMM Tool Kit format */
- SF_FORMAT_SDS = 0x110000, /* Midi Sample Dump Standard */
- SF_FORMAT_AVR = 0x120000, /* Audio Visual Research */
- SF_FORMAT_WAVEX = 0x130000, /* MS WAVE with WAVEFORMATEX */
- SF_FORMAT_SD2 = 0x160000, /* Sound Designer 2 */
- SF_FORMAT_FLAC = 0x170000, /* FLAC lossless file format */
- SF_FORMAT_CAF = 0x180000, /* Core Audio File format */
- SF_FORMAT_WVE = 0x190000, /* Psion WVE format */
- SF_FORMAT_OGG = 0x200000, /* Xiph OGG container */
- SF_FORMAT_MPC2K = 0x210000, /* Akai MPC 2000 sampler */
- SF_FORMAT_RF64 = 0x220000, /* RF64 WAV file */
-
- /* Subtypes from here on. */
-
- SF_FORMAT_PCM_S8 = 0x0001, /* Signed 8 bit data */
- SF_FORMAT_PCM_16 = 0x0002, /* Signed 16 bit data */
- SF_FORMAT_PCM_24 = 0x0003, /* Signed 24 bit data */
- SF_FORMAT_PCM_32 = 0x0004, /* Signed 32 bit data */
-
- SF_FORMAT_PCM_U8 = 0x0005, /* Unsigned 8 bit data (WAV and RAW only) */
-
- SF_FORMAT_FLOAT = 0x0006, /* 32 bit float data */
- SF_FORMAT_DOUBLE = 0x0007, /* 64 bit float data */
-
- SF_FORMAT_ULAW = 0x0010, /* U-Law encoded. */
- SF_FORMAT_ALAW = 0x0011, /* A-Law encoded. */
- SF_FORMAT_IMA_ADPCM = 0x0012, /* IMA ADPCM. */
- SF_FORMAT_MS_ADPCM = 0x0013, /* Microsoft ADPCM. */
-
- SF_FORMAT_GSM610 = 0x0020, /* GSM 6.10 encoding. */
- SF_FORMAT_VOX_ADPCM = 0x0021, /* Oki Dialogic ADPCM encoding. */
-
- 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. */
-
- 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. */
-
- SF_FORMAT_DPCM_8 = 0x0050, /* 8 bit differential PCM (XI only) */
- SF_FORMAT_DPCM_16 = 0x0051, /* 16 bit differential PCM (XI only) */
-
- SF_FORMAT_VORBIS = 0x0060, /* Xiph Vorbis encoding. */
-
- /* Endian-ness options. */
-
- 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. */
-
- 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
-memory allocated during the call to sf_open().
-</P>
-<!-- pepper -->
-<P>
-On success, the sf_open function returns a non-NULL pointer which should be
-passed as the first parameter to all subsequent libsndfile calls dealing with
-that audio file.
-On fail, the sf_open function returns a NULL pointer.
-An explanation of the error can obtained by passing NULL to
- <A HREF="#error">sf_strerror</A>.
-</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>
-
-<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>
-<P>
-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
-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().
- <LI>Opening sound files embedded within larger files.
- <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
-memory allocated during the call to sf_open().
-</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.
-</P>
-
-<P>
-On success, the sf_open_fd function returns a non-NULL pointer which should be
-passed as the first parameter to all subsequent libsndfile calls dealing with
-that audio file.
-On fail, the sf_open_fd function returns a NULL pointer.
-</P>
-
-<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>
-
-
-<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
-the non-audio data is ignored and the seek only moves within the audio data section of
-the file.
-In addition, seeks are defined in number of (multichannel) frames.
-Therefore, a seek in a stereo file from the current position forward with an offset
-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>
-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
-be modified separately.
-If the SEEK_* values are used on their own, the read and write pointers are
-both modified.
-</P>
-
-<P>
-Note that the frames offset can be negative and in fact should be when SEEK_END is used for the
-whence parameter.
-</P>
-<P>
-sf_seek will return the offset in (multichannel) frames from the start of the audio data
-or -1 if an error occured (ie an attempt is made to seek beyond the start or end of the file).
-</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,
- SF_ERR_UNRECOGNISED_FORMAT = 1,
- SF_ERR_SYSTEM = 2,
- SF_ERR_MALFORMED_FILE = 3,
- SF_ERR_UNSUPPORTED_ENCODING = 4
- } ;
-</PRE>
-<!-- pepper -->
-<P>
-or any one of many other internal error values.
-Applications should only test the return value against error values defined in
-<sndfile.h> as the internal error values are subject to change at any
-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>
-The error functions sf_strerror() and sf_error_number() convert the library's internal
-error enumerations into text strings.
-</P>
-<PRE>
- int sf_perror (SNDFILE *sndfile) ;
- int sf_error_str (SNDFILE *sndfile, char* str, size_t len) ;
-</PRE>
-
-<P>
-The functions sf_perror() and sf_error_str() are deprecated and will be dropped
-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>
-The close function closes the file, deallocates its internal buffers and returns
-0 on success or an error value otherwise.
-</P>
-<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
-to force the writing of all file cache buffers to disk. If the file is opened
-SFM_READ no action is taken.
-</P>
-<BR>
-
-
-<A NAME="read"></A>
-<H2><BR><B>File Read Functions (Items)</B></H2>
-
-<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>
-
-<P>
-The file read items functions fill the array pointed to by ptr with the requested
-number of items. The items parameter must be an integer product of the number
-of channels or an error will occur.
-</P>
-<!-- pepper -->
-<P>
-It is important to note that 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
-<A HREF="#note1">Note 1</A>.
-</P>
-<!-- pepper -->
-<P>
-The sf_read_XXXX functions return the number of items read.
-Unless the end of the file was reached during the read, the return value should
-equal the number of items requested.
-Attempts to read beyond the end of the file will not result in an error but will
-cause the sf_read_XXXX functions to return less than the number of items requested
-or 0 if already at the end of the file.
-</P>
-
-<A NAME="readf"></A>
-<H2><BR><B>File Read Functions (Frames)</B></H2>
-
-<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>
-The file read frames functions fill the array pointed to by ptr with the requested
-number of frames of data. The array must be large enough to hold the product of
-frames and the number of channels.
-</P>
-
-<P><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).
-</B></P>
-
-<P>
-The sf_readf_XXXX functions return the number of frames read.
-Unless the end of the file was reached during the read, the return value should equal
-the number of frames requested.
-Attempts to read beyond the end of the file will not result in an error but will cause
-the sf_readf_XXXX functions to return less than the number of frames requested or 0 if
-already at the end of the file.
-</P>
-
-<A NAME="write"></A>
-<H2><BR><B>File Write Functions (Items)</B></H2>
-
-<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>
-
-<P>
-The file write items functions write the data in the array pointed to by ptr to the file.
-The items parameter must be an integer product of the number of channels or an error
-will occur.
-</P>
-<!-- pepper -->
-<P>
-It is important to note that 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 write the data using sf_write_float(). The library
-seamlessly converts between the two formats on-the-fly. See
-<A HREF="#note1">Note 1</A>.
-</P>
-<P>
-The sf_write_XXXX functions return the number of items written (which should be the
-same as the items parameter).
-</P>
-
-<A NAME="writef"></A>
-<H2><BR><B>File Write Functions (Frames)</B></H2>
-
-<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>
-The file write frames functions write the data in the array pointed to by ptr to the file.
-The array must be large enough to hold the product of frames and the number of channels.
-</P>
-<P>
-The sf_writef_XXXX functions return the number of frames written (which should be the
-same as the frames parameter).
-</P>
-
-<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>
-
-<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>
-
-<P>
-The raw read and write functions read raw audio data from the audio file (not to be
-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
-of bytes required to represent one sample from one channel.
-</P>
-<!-- pepper -->
-<P>
-The raw read and write functions return the number of bytes read or written (which
-should be the same as the bytes parameter).
-</P>
-
-<P>
-<B>
-Note : The result of using of both regular reads/writes and raw reads/writes on
-compressed file formats other than SF_FORMAT_ALAW and SF_FORMAT_ULAW is undefined.
-</B>
-</P>
-
-<p>
-See also : <a href="command.html#SFC_RAW_NEEDS_ENDSWAP">SFC_RAW_NEEDS_ENDSWAP</a>
-</p>
-
-<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>
-These functions allow strings to be set on files opened for write and to be
-retrieved from files opened for read where supported by the given file type.
-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,
- SF_STR_DATE,
- SF_STR_ALBUM,
- SF_STR_LICENSE,
- SF_STR_TRACKNUMBER,
- SF_STR_GENRE
- } ;
-</PRE>
-
-<P>
-The sf_get_string() function returns the specified string if it exists and a
-NULL pointer otherwise.
-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.
-</P>
-
-<P>
-The sf_set_string() function sets the string data.
-It returns zero on success and non-zero on error.
-The error code can be converted to a string using sf_error_number().
-</P>
-
-
-<P>
-
-</P>
-
-<HR>
-
-<A NAME="note1"></A>
-<H2><BR><B>Note 1</B></H2>
-<!-- pepper -->
-<P>
-When converting between integer PCM formats of differing size (ie using sf_read_int()
-to read a 16 bit PCM encoded WAV file) libsndfile obeys one simple rule:
-</P>
-
-<P CLASS=indent_block>
-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.
-</P>
-
-<P>
-When converting between integer data and floating point data, different rules apply.
-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
-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>
-Reading a file containg floating point data (allowable with WAV, AIFF, AU and other
-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>
-interface, a command of
- <A HREF="command.html#SFC_SET_SCALE_FLOAT_INT_READ">SFC_SET_SCALE_FLOAT_INT_READ</A>
-and a parameter of SF_TRUE to force correct scaling.
-</P>
-<!-- pepper -->
-<HR>
-<!-- pepper -->
-<P>
- The libsndfile home page is
- <A HREF="http://www.mega-nerd.com/libsndfile/">here</A>.
-</P>
-<P>
-Version : 1.0.25
-</P>
-<!-- pepper -->
-<!-- pepper -->
-<!-- pepper -->
-<!-- pepper -->
-
-</BODY>
-</HTML>
projects / Faustine.git / blobdiff