+++ /dev/null
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- <TITLE>
- libsndfile : the sf_command function.
- </TITLE>
- <META NAME="Author" CONTENT="Erik de Castro Lopo (erikd AT mega-nerd DOT com)">
- <!-- Another version at the bottom of the page. -->
- <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>
-
-<H1><B>sf_command</B></H1>
-<PRE>
-
- int sf_command (SNDFILE *sndfile, int cmd, void *data, int datasize) ;
-</PRE>
-<P>
- This function allows the caller to retrieve information from or change aspects of the
- library behaviour.
- Examples include retrieving a string containing the library version or changing the
- scaling applied to floating point sample data during read and write.
- Most of these operations are performed on a per-file basis.
-</P>
-<P>
- The cmd parameter is a integer identifier which is defined in <sndfile.h>.
- All of the valid command identifiers have names begining with "SFC_".
- Data is passed to and returned from the library by use of a void pointer.
- The library will not read or write more than datasize bytes from the void pointer.
- For some calls no data is required in which case data should be NULL and datasize
- may be used for some other purpose.
-</P>
-<P>
- The available commands are as follows:
-</P>
-
-<CENTER>
-<TABLE BORDER="0" WIDTH="90%" CELLPADDING="4">
-<TR>
- <TD><A HREF="#SFC_GET_LIB_VERSION">SFC_GET_LIB_VERSION</A></TD>
- <TD>Retrieve the version of the library.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_GET_LOG_INFO">SFC_GET_LOG_INFO</A></TD>
- <TD>Retrieve the internal per-file operation log.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_CALC_SIGNAL_MAX">SFC_CALC_SIGNAL_MAX</A></TD>
- <TD>Retrieve the measured maximum signal value.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_CALC_NORM_SIGNAL_MAX">SFC_CALC_NORM_SIGNAL_MAX</A></TD>
- <TD>Retrieve the measured normalised maximum signal value.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_CALC_MAX_ALL_CHANNELS">SFC_CALC_MAX_ALL_CHANNELS</A></TD>
- <TD>Calculate peaks for all channels.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_CALC_NORM_MAX_ALL_CHANNELS">SFC_CALC_NORM_MAX_ALL_CHANNELS</A></TD>
- <TD>Calculate normalised peaks for all channels.</TD>
-</TR>
-
-<TR>
- <TD><A HREF="#SFC_SET_NORM_FLOAT">SFC_SET_NORM_FLOAT</A></TD>
- <TD>Modify the normalisation behaviour of the floating point reading and writing functions.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_SET_NORM_DOUBLE">SFC_SET_NORM_DOUBLE</A></TD>
- <TD>Modify the normalisation behaviour of the double precision floating point reading and writing functions.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_GET_NORM_FLOAT">SFC_GET_NORM_FLOAT</A></TD>
- <TD>Retrieve the current normalisation behaviour of the floating point reading and writing functions.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_GET_NORM_DOUBLE">SFC_GET_NORM_DOUBLE</A></TD>
- <TD>Retrieve the current normalisation behaviour of the double precision floating point reading and writing functions.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_GET_SIMPLE_FORMAT_COUNT">SFC_GET_SIMPLE_FORMAT_COUNT</A></TD>
- <TD>Retrieve the number of simple formats supported by libsndfile.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_GET_SIMPLE_FORMAT">SFC_GET_SIMPLE_FORMAT</A></TD>
- <TD>Retrieve information about a simple format.</TD>
-</TR>
-
-<TR>
- <TD><A HREF="#SFC_GET_FORMAT_INFO">SFC_GET_FORMAT_INFO</A></TD>
- <TD>Retrieve information about a major or subtype format.</TD>
-</TR>
-
-<TR>
- <TD><A HREF="#SFC_GET_FORMAT_MAJOR_COUNT">SFC_GET_FORMAT_MAJOR_COUNT</A></TD>
- <TD>Retrieve the number of major formats.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_GET_FORMAT_MAJOR">SFC_GET_FORMAT_MAJOR</A></TD>
- <TD>Retrieve information about a major format type.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_GET_FORMAT_SUBTYPE_COUNT">SFC_GET_FORMAT_SUBTYPE_COUNT</A></TD>
- <TD>Retrieve the number of subformats.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_GET_FORMAT_SUBTYPE">SFC_GET_FORMAT_SUBTYPE</A></TD>
- <TD>Retrieve information about a subformat.</TD>
-</TR>
-
-<TR>
- <TD><A HREF="#SFC_SET_ADD_PEAK_CHUNK">SFC_SET_ADD_PEAK_CHUNK</A></TD>
- <TD>Switch the code for adding the PEAK chunk to WAV and AIFF files on or off.</TD>
-</TR>
-
-<TR>
- <TD><A HREF="#SFC_UPDATE_HEADER_NOW">SFC_UPDATE_HEADER_NOW</A></TD>
- <TD>Used when a file is open for write, this command will update the file
- header to reflect the data written so far.</TD>
-</TR>
-<TR>
- <TD><A HREF="#SFC_SET_UPDATE_HEADER_AUTO">SFC_SET_UPDATE_HEADER_AUTO</A></TD>
- <TD>Used when a file is open for write, this command will cause the file header
- to be updated after each write to the file.</TD>
-</TR>
-
-<TR>
- <TD><A HREF="#SFC_FILE_TRUNCATE">SFC_FILE_TRUNCATE</A></TD>
- <TD>Truncate a file open for write or for read/write.</TD>
-</TR>
-
-<TR>
- <TD><A HREF="#SFC_SET_RAW_START_OFFSET">SFC_SET_RAW_START_OFFSET</A></TD>
- <TD>Change the data start offset for files opened up as SF_FORMAT_RAW.</TD>
-</TR>
-
-
-
-<!--
-<TR>
- <TD><A HREF="#add-dither">add dither</A></TD>
- <TD>Add dither to output on write.</TD>
-</TR>
--->
-</TABLE>
-</CENTER>
-
-<BR><BR>
-
-<HR>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_LIB_VERSION"></A>
-<H2><BR><B>SFC_GET_LIB_VERSION</B></H2>
-<P>
-Retrieve the version of the library as a string.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : Not used
- cmd : SFC_GET_LIB_VERSION
- data : A pointer to a char buffer
- datasize : The size of the the buffer
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- char buffer [128] ;
- sf_command (NULL, SFC_GET_LIB_VERSION, buffer, sizeof (buffer)) ;
-</PRE>
-
-<DL>
-<DT>Return value:</DT>
- <DD><DD>This call will return the length of the retrieved version string.
-</DL>
-<DL>
-<DT>Notes:</DT>
-<DD>
-The string returned in the buffer passed to this function will not overflow
-the buffer and will always be null terminated .
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_LOG_INFO"></A>
-<H2><BR><B>SFC_GET_LOG_INFO</B></H2>
-<P>
-Retrieve the log buffer generated when opening a file as a string. This log
-buffer can often contain a good reason for why libsndfile failed to open a
-particular file.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_GET_LOG_INFO
- data : A pointer to a char buffer
- datasize : The size of the the buffer
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- char buffer [2048] ;
- sf_command (sndfile, SFC_GET_LOG_INFO, buffer, sizeof (buffer)) ;
-</PRE>
-
-<DL>
-<DT>Return value:</DT>
- <DD><DD>This call will return the length of the retrieved version string.
-</DL>
-<DL>
-<DT>Notes:</DT>
-<DD>
-The string returned in the buffer passed to this function will not overflow
-the buffer and will always be null terminated .
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_CALC_SIGNAL_MAX"></A>
-<H2><BR><B>SFC_CALC_SIGNAL_MAX</B></H2>
-<P>
-Retrieve the measured maximum signal value. This involves reading through
-the whole file which can be slow on large files.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_CALC_SIGNAL_MAX
- data : A pointer to a double
- datasize : sizeof (double)
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- double max_val ;
- sf_command (sndfile, SFC_CALC_SIGNAL_MAX, &max_val, sizeof (max_val)) ;
-</PRE>
-
-<DL>
-<DT>Return value:</DT>
- <DD><DD>Zero on success, non-zero otherwise.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_CALC_NORM_SIGNAL_MAX"></A>
-<H2><BR><B>SFC_CALC_NORM_SIGNAL_MAX</B></H2>
-<P>
-Retrieve the measured normailised maximum signal value. This involves reading
-through the whole file which can be slow on large files.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_CALC_NORM_SIGNAL_MAX
- data : A pointer to a double
- datasize : sizeof (double)
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- double max_val ;
- sf_command (sndfile, SFC_CALC_NORM_SIGNAL_MAX, &max_val, sizeof (max_val)) ;
-</PRE>
-
-<DL>
-<DT>Return value:</DT>
- <DD><DD>Zero on success, non-zero otherwise.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_CALC_MAX_ALL_CHANNELS"></A>
-<H2><BR><B>SFC_CALC_MAX_ALL_CHANNELS</B></H2>
-<P>
-Calculate peaks for all channels. This involves reading through
-the whole file which can be slow on large files.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_CALC_MAX_ALL_CHANNELS
- data : A pointer to a double
- datasize : sizeof (double) * number_of_channels
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- double peaks [number_of_channels] ;
- sf_command (sndfile, SFC_CALC_MAX_ALL_CHANNELS, peaks, sizeof (peaks)) ;
-</PRE>
-<DL>
-<DT>Return value:</DT>
- <DD>Zero if peaks have been calculated successfully and non-zero otherwise.
-</DL>
-
-
-<!-- ========================================================================= -->
-<A NAME="SFC_CALC_NORM_MAX_ALL_CHANNELS"></A>
-<H2><BR><B>SFC_CALC_NORM_MAX_ALL_CHANNELS</B></H2>
-<P>
-Calculate normalised peaks for all channels. This involves reading through
-the whole file which can be slow on large files.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_CALC_NORM_MAX_ALL_CHANNELS
- data : A pointer to a double
- datasize : sizeof (double) * number_of_channels
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- double peaks [number_of_channels] ;
- sf_command (sndfile, SFC_CALC_NORM_MAX_ALL_CHANNELS, peaks, sizeof (peaks)) ;
-</PRE>
-<DL>
-<DT>Return value:</DT>
- <DD>Zero if peaks have been calculated successfully and non-zero otherwise.
-</DL>
-
-
-
-
-
-<!-- ========================================================================= -->
-<!--
-<A NAME="read-text"></A>
-<H2><BR><B>Read text</B></H2>
-<P>
-Many sound file formats contain allow the inclusion of a text string describing the nature
-of the file. If a file contains such a string, this functions will return it to the caller.
-</P>
-<P>
-It should be noted that the way the string is added to the file is file format dependant
-but that any string added with <A HREF="#write-text">write text</A> will be returned by
-<A HREF="#read-text">read text</A>.
-</P>
-<P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : The text string "read text".
- data : A pointer to a char buffer.
- datasize : The size of the the buffer.
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- char buffer [128] ;
- sf_command (sndfile, "read text", buffer, sizeof (buffer)) ;
-</PRE>
-<DL>
-<DT>Return value:</DT>
-<DD>If a text string is found, this call will return the length of the retrieved text
- string.
- <DD>If no text string is found, zero will be returned and the first element in the
- buffer will be set to the null character.
-<DT>Notes:</DT>
-<DD>The string returned in the buffer passed to this function will not overflow
- the buffer and will be correctly null terminated .
-</DL>
-
-<A NAME="write-text"></A>
-<H2><BR><B>Write text</B></H2>
-<P>
-Add a text string to a file. The text string added can be retrieved when the file is
-read using <A HREF="#read-text">read text</A>.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : The text string "write text".
- data : A pointer to the string to be added.
- datasize : Not used.
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- char text = "The sound of one hand clapping." ;
- sf_command (sndfile, "write text", text, strlen (text)) ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>If the current file format allows the addition of text strings, the string will
- be added and the length of the string will be returned.
- <DD>If the file format does not allow the addition of text strings zero will be returned.
- <DD>If this function is called after the file is openned but before
-</DL>
--->
-
-
-<!-- ========================================================================= -->
-<A NAME="SFC_SET_NORM_FLOAT"></A>
-<H2><BR><B>SFC_SET_NORM_FLOAT</B></H2>
-<P>
-This command only affects data read from or written to using the floating point functions:
-</P>
-<PRE>
- size_t <A HREF="api.html#read">sf_read_float</A> (SNDFILE *sndfile, float *ptr, size_t items) ;
- size_t <A HREF="api.html#readf">sf_readf_float</A> (SNDFILE *sndfile, float *ptr, size_t frames) ;
-
- size_t <A HREF="api.html#write">sf_write_float</A> (SNDFILE *sndfile, float *ptr, size_t items) ;
- size_t <A HREF="api.html#writef">sf_writef_float</A> (SNDFILE *sndfile, float *ptr, size_t frames) ;
-</PRE>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_SET_NORM_FLOAT
- data : NULL
- datasize : SF_TRUE or SF_FALSE
-</PRE>
-<P>
-For read operations setting normalisation to SF_TRUE means that the data from all
-subsequent reads will be be normalised to the range [-1.0, 1.0].
-</P>
-<P>
-For write operations, setting normalisation to SF_TRUE means than all data supplied
-to the float write functions should be in the range [-1.0, 1.0] and will be scaled
-for the file format as necessary.
-</P>
-<P>
-For both cases, setting normalisation to SF_FALSE means that no scaling will take place.
-</P>
-<P>
-Example:
-</P>
-<PRE>
- sf_command (sndfile, SFC_SET_NORM_FLOAT, NULL, SF_TRUE) ;
-
- sf_command (sndfile, SFC_SET_NORM_FLOAT, NULL, SF_FALSE) ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>Returns 1 on success or 0 for failure.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_SET_NORM_DOUBLE"></A>
-<H2><BR><B>SFC_SET_NORM_DOUBLE</B></H2>
-<P>
-This command only affects data read from or written to using the double precision
-floating point functions:
-</P>
-<PRE>
- size_t <A HREF="api.html#read">sf_read_double</A> (SNDFILE *sndfile, double *ptr, size_t items) ;
- size_t <A HREF="api.html#readf">sf_readf_double</A> (SNDFILE *sndfile, double *ptr, size_t frames) ;
-
- size_t <A HREF="api.html#write">sf_write_double</A> (SNDFILE *sndfile, double *ptr, size_t items) ;
- size_t <A HREF="api.html#writef">sf_writef_double</A> (SNDFILE *sndfile, double *ptr, size_t frames) ;
-</PRE>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_SET_NORM_DOUBLE
- data : NULL
- datasize : SF_TRUE or SF_FALSE
-</PRE>
-<P>
-For read operations setting normalisation to SF_TRUE means that the data
-from all subsequent reads will be be normalised to the range [-1.0, 1.0].
-</P>
-<P>
-For write operations, setting normalisation to SF_TRUE means than all data supplied
-to the double write functions should be in the range [-1.0, 1.0] and will be scaled
-for the file format as necessary.
-</P>
-<P>
-For both cases, setting normalisation to SF_FALSE means that no scaling will take place.
-</P>
-<P>
-Example:
-</P>
-<PRE>
- sf_command (sndfile, SFC_SET_NORM_DOUBLE, NULL, SF_TRUE) ;
-
- sf_command (sndfile, SFC_SET_NORM_DOUBLE, NULL, SF_FALSE) ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>Returns 1 on success or 0 for failure.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_NORM_FLOAT"></A>
-<H2><BR><B>SFC_GET_NORM_FLOAT</B></H2>
-<P>
-Retrieve the current float normalisation mode.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_GET_NORM_FLOAT
- data : NULL
- datasize : anything
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- normalisation = sf_command (sndfile, SFC_GET_NORM_FLOAT, NULL, 0) ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>Returns TRUE if normaisation is on and FALSE otherwise.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_NORM_DOUBLE"></A>
-<H2><BR><B>SFC_GET_NORM_DOUBLE</B></H2>
-<P>
-Retrieve the current float normalisation mode.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_GET_NORM_DOUBLE
- data : NULL
- datasize : anything
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- normalisation = sf_command (sndfile, SFC_GET_NORM_DOUBLE, NULL, 0) ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>Returns TRUE if normalisation is on and FALSE otherwise.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_SIMPLE_FORMAT_COUNT"></A>
-<H2><BR><B>SFC_GET_SIMPLE_FORMAT_COUNT</B></H2>
-<P>
-Retrieve the number of simple formats supported by libsndfile.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : Not used.
- cmd : SFC_GET_SIMPLE_FORMAT_COUNT
- data : a pointer to an int
- datasize : sizeof (int)
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- int count ;
- sf_command (sndfile, SFC_GET_SIMPLE_FORMAT_COUNT, &count, sizeof (int)) ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>0
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_SIMPLE_FORMAT"></A>
-<H2><BR><B>SFC_GET_SIMPLE_FORMAT</B></H2>
-<P>
-Retrieve information about a simple format.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : Not used.
- cmd : SFC_GET_SIMPLE_FORMAT
- data : a pointer to an SF_FORMAT_INFO struct
- datasize : sizeof (SF_FORMAT_INFO)
-</PRE>
-<P>
-The SF_FORMAT_INFO struct is defined in <sndfile.h> as:
-</P>
-<PRE>
- typedef struct
- { int format ;
- const char *name ;
- const char *extension ;
- } SF_FORMAT_INFO ;
-</PRE>
-<P>
-When sf_command() is called with SF_GET_SIMPLE_FORMAT, the value of the format
-field should be the format number (ie 0 <= format <= count value obtained using
-SF_GET_SIMPLE_FORMAT_COUNT).
-</P>
-<P>
-Example:
-</P>
-<PRE>
- SF_FORMAT_INFO format_info ;
- int k, count ;
-
- sf_command (sndfile, SFC_GET_SIMPLE_FORMAT_COUNT, &count, sizeof (int)) ;
-
- for (k = 0 ; k < count ; k++)
- { format_info.format = k ;
- sf_command (sndfile, SFC_GET_SIMPLE_FORMAT, &format_info, sizeof (format_info)) ;
- printf ("%08x %s %s\n", format_info.format, format_info.name, format_info.extension) ;
- } ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>0 on success and non-zero otherwise.
- <DD>The value of the format field of the SF_FORMAT_INFO struct will be an value which
- can be placed in the format field of an SF_INFO struct when a file is to be opened
- for write.
- <DD>The name field will contain a char* pointer to the name of the string ie "WAV (Microsoft 16 bit PCM)".
- <DD>The extention field will contain the most commonly used file extension for that file type.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_FORMAT_INFO"></A>
-<H2><BR><B>SFC_GET_FORMAT_INFO</B></H2>
-<P>
-Retrieve information about a major or subtype format.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : Not used.
- cmd : SFC_GET_FORMAT_INFO
- data : a pointer to an SF_FORMAT_INFO struct
- datasize : sizeof (SF_FORMAT_INFO)
-</PRE>
-<P>
-The SF_FORMAT_INFO struct is defined in <sndfile.h> as:
-</P>
-<PRE>
- typedef struct
- { int format ;
- const char *name ;
- const char *extension ;
- } SF_FORMAT_INFO ;
-</PRE>
-<P>
-When sf_command() is called with SF_GET_FORMAT_INFO, the format field is
-examined and if (format & SF_FORMAT_TYPEMASK) is a valid format then the struct
-is filled in with information about the given major type.
-If (format & SF_FORMAT_TYPEMASK) is FALSE and (format & SF_FORMAT_SUBMASK) is a
-valid subtype format then the struct is filled in with information about the given
-subtype.
-</P>
-<P>
-Example:
-</P>
-<PRE>
- SF_FORMAT_INFO format_info ;
-
- format_info.format = SF_FORMAT_WAV ;
- sf_command (sndfile, SFC_GET_FORMAT_INFO, &format_info, sizeof (format_info)) ;
- printf ("%08x %s %s\n", format_info.format, format_info.name, format_info.extension) ;
-
- format_info.format = SF_FORMAT_ULAW ;
- sf_command (sndfile, SFC_GET_FORMAT_INFO, &format_info, sizeof (format_info)) ;
- printf ("%08x %s\n", format_info.format, format_info.name) ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>0 on success and non-zero otherwise.
-</DL>
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_FORMAT_MAJOR_COUNT"></A>
-<H2><BR><B>SFC_GET_FORMAT_MAJOR_COUNT</B></H2>
-<P>
-Retrieve the number of major formats.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : Not used.
- cmd : SFC_GET_FORMAT_MAJOR_COUNT
- data : a pointer to an int
- datasize : sizeof (int)
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- int count ;
- sf_command (sndfile, SFC_GET_FORMAT_MAJOR_COUNT, &count, sizeof (int)) ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>0
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_FORMAT_MAJOR"></A>
-<H2><BR><B>SFC_GET_FORMAT_MAJOR</B></H2>
-<P>
-Retrieve information about a major format type.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : Not used.
- cmd : SFC_GET_FORMAT_MAJOR
- data : a pointer to an SF_FORMAT_INFO struct
- datasize : sizeof (SF_FORMAT_INFO)
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- SF_FORMAT_INFO format_info ;
- int k, count ;
-
- sf_command (sndfile, SFC_GET_FORMAT_MAJOR_COUNT, &count, sizeof (int)) ;
-
- for (k = 0 ; k < count ; k++)
- { format_info.format = k ;
- sf_command (sndfile, SFC_GET_FORMAT_MAJOR, &format_info, sizeof (format_info)) ;
- printf ("%08x %s %s\n", format_info.format, format_info.name, format_info.extension) ;
- } ;
-</PRE>
-<P>
-For a more comprehensive example, see the program list_formats.c in the examples/
-directory of the libsndfile source code distribution.
-</P>
-<DL>
-<DT>Return value: </DT>
- <DD>0 on success and non-zero otherwise.
- <DD>The value of the format field will one of the major format identifiers suc as SF_FORMAT_WAV
- SF_FORMAT_AIFF.
- <DD>The name field will contain a char* pointer to the name of the string ie "WAV (Microsoft)".
- <DD>The extention field will contain the most commonly used file extension for that file type.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_FORMAT_SUBTYPE_COUNT"></A>
-<H2><BR><B>SFC_GET_FORMAT_SUBTYPE_COUNT</B></H2>
-<P>
-Retrieve the number of subformats.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : Not used.
- cmd : SFC_GET_FORMAT_SUBTYPE_COUNT
- data : a pointer to an int
- datasize : sizeof (int)
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- int count ;
- sf_command (sndfile, SFC_GET_FORMAT_SUBTYPE_COUNT, &count, sizeof (int)) ;
-</PRE>
-<DL>
-<DT>Return value: </DT>
- <DD>0
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_GET_FORMAT_SUBTYPE"></A>
-<H2><BR><B>SFC_GET_FORMAT_SUBTYPE</B></H2>
-<P>
-Retrieve information about a subformat.
-</P>
-<P>
-Parameters:
-</P>
-<PRE>
- sndfile : Not used.
- cmd : SFC_GET_FORMAT_SUBTYPE
- data : a pointer to an SF_FORMAT_INFO struct
- datasize : sizeof (SF_FORMAT_INFO)
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- SF_FORMAT_INFO format_info ;
- int k, count ;
-
- sf_command (sndfile, SFC_GET_FORMAT_SUBTYPE_COUNT, &count, sizeof (int)) ;
-
- /* Retrieve all the subtypes supported by the WAV format. */
- for (k = 0 ; k < count ; k++)
- { format_info.format = k ;
- sf_command (sndfile, SFC_GET_FORMAT_SUBTYPE, &format_info, sizeof (format_info)) ;
- if (! sf_format_check (format.info | SF_FORMAT_WAV))
- continue ;
- printf ("%08x %s\n", format_info.format, format_info.name) ;
- } ;
-</PRE>
-<P>
-For a more comprehensive example, see the program list_formats.c in the examples/
-directory of the libsndfile source code distribution.
-</P>
-<DL>
-<DT>Return value: </DT>
- <DD>0 on success and non-zero otherwise.
- <DD>The value of the format field will one of the major format identifiers such as SF_FORMAT_WAV
- SF_FORMAT_AIFF.
- <DD>The name field will contain a char* pointer to the name of the string; for instance
- "WAV (Microsoft)" or "AIFF (Apple/SGI)".
- <DD>The extention field will be a NULL pointer.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_SET_ADD_PEAK_CHUNK"></A>
-<H2><BR><B>SFC_SET_ADD_PEAK_CHUNK</B></H2>
-<P>
-By default, WAV and AIFF files which contain floating point data (subtype SF_FORMAT_FLOAT
-or SF_FORMAT_DOUBLE) have a PEAK chunk.
-By using this command, the addition of a PEAK chunk can be turned on or off.
-</P>
-<P>
-Note : This call must be made before any data is written to the file.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_SET_ADD_PEAK_CHUNK
- data : Not used (should be NULL)
- datasize : TRUE or FALSE.
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- /* Turn on the PEAK chunk. */
- sf_command (sndfile, SFC_SET_ADD_PEAK_CHUNK, NULL, SF_TRUE) ;
-
- /* Turn off the PEAK chunk. */
- sf_command (sndfile, SFC_SET_ADD_PEAK_CHUNK, NULL, SF_FALSE) ;
-</PRE>
-<DL>
-<DT>Return value:</DT>
-<DD>Returns SF_TRUE if the peak chunk will be written after this call.
-<DD>Returns SF_FALSE if the peak chunk will not be written after this call.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_UPDATE_HEADER_NOW"></A>
-<H2><BR><B>SFC_UPDATE_HEADER_NOW</B></H2>
-<P>
-The header of an audio file is normally written by libsndfile when the file is
-closed using <B>sf_close()</B>.
-</P>
-<P>
-There are however situations where large files are being generated and it would
-be nice to have valid data in the header before the file is complete.
-Using this command will update the file header to reflect the amount of data written
-to the file so far.
-Other programs opening the file for read (before any more data is written) will
-then read a valid sound file header.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_UPDATE_HEADER_NOW
- data : Not used (should be NULL)
- datasize : Not used.
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- /* Update the header now. */
- sf_command (sndfile, SFC_UPDATE_HEADER_NOW, NULL, 0) ;
-</PRE>
-<DL>
-<DT>Return value:</DT>
-<DD>0
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_SET_UPDATE_HEADER_AUTO"></A>
-<H2><BR><B>SFC_SET_UPDATE_HEADER_AUTO</B></H2>
-<P>
-Similar to SFC_UPDATE_HEADER_NOW but updates the header at the end of every call
-to the <B>sf_write*</B> functions.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_UPDATE_HEADER_NOW
- data : Not used (should be NULL)
- datasize : SF_TRUE or SF_FALSE
-</PRE>
-<P>
-Example:
-</P>
-<PRE>
- /* Turn on auto header update. */
- sf_command (sndfile, SFC_SET_UPDATE_HEADER_AUTO, NULL, SF_TRUE) ;
-
- /* Turn off auto header update. */
- sf_command (sndfile, SFC_SET_UPDATE_HEADER_AUTO, NULL, SF_FALSE) ;
-</PRE>
-<DL>
-<DT>Return value:</DT>
-<DD>TRUE if auto update header is now on; FALSE otherwise.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_FILE_TRUNCATE"></A>
-<H2><BR><B>SFC_FILE_TRUNCATE</B></H2>
-<P>
-Truncate a file open for write or for read/write.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_FILE_TRUNCATE
- data : A pointer to an sf_count_t.
- datasize : sizeof (sf_count_t)
-</PRE>
-
-<P>
-Truncate the file to the number of frames specified by the sf_count_t pointed
-to by data.
-After this command, both the read and the write pointer will be
-at the new end of the file.
-This command will fail (returning non-zero) if the requested truncate position
-is beyond the end of the file.
-</P>
-<P>
-Example:
-</P>
-<PRE>
- /* Truncate the file to a length of 20 frames. */
- sf_count_t frames = 20 ;
- sf_command (sndfile, SFC_FILE_TRUNCATE, &frames, sizeof (frames)) ;
-</PRE>
-<DL>
-<DT>Return value:</DT>
- <DD>Zero on sucess, non-zero otherwise.
-</DL>
-
-<!-- ========================================================================= -->
-<A NAME="SFC_SET_RAW_START_OFFSET"></A>
-<H2><BR><B>SFC_SET_RAW_START_OFFSET</B></H2>
-<P>
-Change the data start offset for files opened up as SF_FORMAT_RAW.
-</P>
-<P>
-Parameters:
-<PRE>
- sndfile : A valid SNDFILE* pointer
- cmd : SFC_SET_RAW_START_OFFSET
- data : A pointer to an sf_count_t.
- datasize : sizeof (sf_count_t)
-</PRE>
-
-<P>
-For a file opened as format SF_FORMAT_RAW, set the data offset to the value
-given by data.
-</P>
-<P>
-Example:
-</P>
-<PRE>
- /* Reset the data offset to 5 bytes from the start of the file. */
- sf_count_t offset = 5 ;
- sf_command (sndfile, SFC_SET_RAW_START_OFFSET, &offset, sizeof (offset)) ;
-</PRE>
-<DL>
-<DT>Return value:</DT>
- <DD>Zero on sucess, non-zero otherwise.
-</DL>
-
-<!-- ========================================================================= -->
-
-<HR>
-<P>
- The libsndfile home page is here :
- <A HREF="http://www.mega-nerd.com/libsndfile/">
- http://www.mega-nerd.com/libsndfile/</A>.
-<BR>
-Version : 1.0.25
-</P>
-
-</BODY>
-</HTML>
projects / Faustine.git / blobdiff