TABLE OF CONTENTS sndfile.library/--background-- sndfile.library/SF_GetLibVersion sndfile.library/SF_OpenRead sndfile.library/SF_OpenWrite sndfile.library/SF_Close sndfile.library/SF_ReadRaw sndfile.library/SF_WriteRaw sndfile.library/SF_ReadChar sndfile.library/SF_WriteChar sndfile.library/SF_ReadShort sndfile.library/SF_WriteShort sndfile.library/SF_ReadInt sndfile.library/SF_WriteInt sndfile.library/SF_ReadDouble sndfile.library/SF_WriteDouble sndfile.library/SF_ReadFChar sndfile.library/SF_WriteFChar sndfile.library/SF_ReadFShort sndfile.library/SF_WriteFShort sndfile.library/SF_ReadFInt sndfile.library/SF_WriteFInt sndfile.library/SF_ReadFDouble sndfile.library/SF_WriteFDouble sndfile.library/SF_Seek sndfile.library/SF_FormatCheck sndfile.library/SF_SignalMax sndfile.library/SF_GetHeaderInfo sndfile.library/SF_ErrorStr sndfile.library/--background-- PURPOSE This shared library is derived from from Erik de Castro Lopo's excellent libsndfile link library. 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. CAPABILITIES Libsndfile is currently capable of reading and writing the following sound file formats: o Microsoft WAV 8, 16, 24 and 32 bit integer PCM. o Microsoft 32 bit floating point PCM. o Microsoft IMA/DVI ADPCM WAV format (16 bits per sample compressed to 4 bits per sample). o Microsoft ADPCM WAV format (16 bits per sample compressed to 4 bits per sample). o Microsoft 8 bit A-law an u-law formats (16 bits per sample compressed to 8 bits per sample). o Microsoft WAV files using GSM 6.10 encoding. o Apple/SGI AIFF and AIFC uncompressed 8, 16, 24 and 32 bit integer PCM. o Sun/NeXT AU/SND format (big endian 8, 16, 24 and 32 bit PCM, 8 bit u-law and 8 bit A-law). o Dec AU format (little endian 8, 16, 24 and 32 bit PCM, 8 bit u-law and 8 bit A-law). o RAW header-less PCM files of 8 (signed and unsigned), 16, 24 and 32 bits. The 16, 24 and 32 bit files may be big or little endian byte ordering. o Amiga uncompressed IFF / 8SVX / 16SV PCM files (8 and 16 bit). o Ensoniq PARIS big and little endian, 16 and 24 bit PCM files (.PAF). More information can be obtained here: http://www.zip.com.au/~erikd/libsndfile/ SYNOPSIS The functions of sndfile.library are almost identical to those of libsndfile with the following exceptions: o Different capitalization (f.ex. sf_readf_int() == SF_ReadFInt()). o There's no SF_PError() (because of the way libraries work), see example in SF_ErrorStr() doc on how to emulate this. o SF_SignalMax() returns a pointer to double instead of double. Any libsndfile program can be made to use sndfile.library by linking with one of the included linklibs that are appropriate to your compiler/options. The functions of libsndfile are defined as follows: SNDFILE* sf_open_read (const char *path, SF_INFO *sfinfo) ; SNDFILE* sf_open_write (const char *path, const SF_INFO *sfinfo) ; int sf_perror (SNDFILE *sndfile) ; int sf_error_str (SNDFILE *sndfile, char* str, size_t len) ; int sf_error_number (int errnum, char* str, size_t len) ; size_t sf_get_header_info (SNDFILE *sndfile, char* buffer, size_t bufferlen, size_t offset) ; size_t sf_get_lib_version (char* buffer, size_t bufferlen) ; int sf_format_check (const SF_INFO *info) ; double sf_signal_max (SNDFILE *sndfile) ; off_t sf_seek (SNDFILE *sndfile, off_t frames, int whence) ; size_t sf_read_raw (SNDFILE *sndfile, void *ptr, size_t bytes) ; size_t sf_write_raw (SNDFILE *sndfile, void *ptr, size_t bytes) ; size_t sf_read_short (SNDFILE *sndfile, short *ptr, size_t items) ; size_t sf_read_int (SNDFILE *sndfile, int *ptr, size_t items) ; size_t sf_read_double (SNDFILE *sndfile, double *ptr, size_t items, int normalize) ; size_t sf_readf_short (SNDFILE *sndfile, short *ptr, size_t frames) ; size_t sf_readf_int (SNDFILE *sndfile, int *ptr, size_t frames) ; size_t sf_readf_double (SNDFILE *sndfile, double *ptr, size_t frames, int normalize) ; size_t sf_write_short (SNDFILE *sndfile, short *ptr, size_t items) ; size_t sf_write_int (SNDFILE *sndfile, int *ptr, size_t items) ; size_t sf_write_double (SNDFILE *sndfile, double *ptr, size_t items, int normalize) ; size_t sf_writef_short (SNDFILE *sndfile, short *ptr, size_t frames) ; size_t sf_writef_int (SNDFILE *sndfile, int *ptr, size_t frames) ; size_t sf_writef_double (SNDFILE *sndfile, double *ptr, size_t frames, int normalize) ; int sf_close (SNDFILE *sndfile) ; SNDFILE* is an anonymous pointer to data which is private to the library. The SF_INFO structure is for passing data between the calling function and the library when opening a file for read or writing. It is defined in sndfile.h as follows: typedef struct { int samplerate ; int samples ; int channels ; int pcmbitwidth ; int format ; int sections ; int seekable ; } SF_INFO ; The format field in the above structure is made up of the bit-wise OR of a major format type with a value of 0x10000 or greater and a minor format type with a value less than 0x10000. The currently understood formats are listed in sndfile.h as follows and also includes two bitmasks for separating major and minor file types. Not all combinations of major and minor file types are valid. enum { SF_FORMAT_WAV = 0x10000, /* Microsoft WAV format (big endian). */ SF_FORMAT_AIFF = 0x20000, /* Apple/SGI AIFF format (little endian). */ SF_FORMAT_AU = 0x30000, /* Sun/NeXT AU format (big endian). */ SF_FORMAT_AULE = 0x40000, /* DEC AU format (little endian). */ SF_FORMAT_RAW = 0x50000, /* RAW PCM data. */ SF_FORMAT_PAF = 0x60000, /* Ensoniq PARIS file format. */ SF_FORMAT_SVX = 0x70000, /* Amiga IFF / SVX8 / SV16 format. */ SF_FORMAT_NIST = 0x80000, /* Sphere NIST format. */ SF_FORMAT_PCM = 0x0001, /* PCM data in 8, 16, 24 or 32 bits. */ SF_FORMAT_FLOAT = 0x0002, /* 32 bit floats. */ SF_FORMAT_ULAW = 0x0003, /* U-Law encoded. */ SF_FORMAT_ALAW = 0x0004, /* A-Law encoded. */ SF_FORMAT_IMA_ADPCM = 0x0005, /* IMA ADPCM. */ SF_FORMAT_MS_ADPCM = 0x0006, /* Microsoft ADPCM. */ SF_FORMAT_PCM_BE = 0x0007, /* Big endian PCM data. */ SF_FORMAT_PCM_LE = 0x0008, /* Little endian PCM data. */ SF_FORMAT_PCM_S8 = 0x0009, /* Signed 8 bit PCM. */ SF_FORMAT_PCM_U8 = 0x000A, /* Unsigned 8 bit PCM. */ SF_FORMAT_PCM_BE = 0x0007, /* RAW PCM (big endian). */ SF_FORMAT_PCM_LE = 0x0008, /* RAW PCM (little endian). */ SF_FORMAT_RAW_S8 = 0x0009, /* Signed 8 bit RAW PCM. */ SF_FORMAT_RAW_U8 = 0x000A, /* Unsigned 8 bit RAW PCM. */ SF_FORMAT_SVX_FIB = 0x000B, /* SVX Fibonacci Delta encoding. */ SF_FORMAT_SVX_EXP = 0x000C, /* SVX Exponential Delta encoding. */ SF_FORMAT_GSM610 = 0x000D, /* GSM 6.10 encoding. */ SF_FORMAT_G721_32 = 0x000E, /* 32kbs G721 ADPCM encoding. */ SF_FORMAT_G723_24 = 0x000F, /* 24kbs G723 ADPCM encoding. */ SF_FORMAT_SUBMASK = 0xFFFF, SF_FORMAT_TYPEMASK = 0x7FFF0000 } ; sndfile.library/SF_GetLibVersion sndfile.library/SF_GetLibVersion NAME SF_GetLibVersion - Get the library version string. SYNOPSIS length = SF_GetLibVersion(buffer, bufferlen) A0 D0 size_t SF_GetLibVersion(char *, size_t); FUNCTION Fill in the provided buffer with the library version string. NOTE EXAMPLE size_t len; char buf[256]; len = SF_GetLibVersion(buf, sizeof(buf)); printf("Length: %d String: %s\n", len, buf); INPUTS buffer - pointer to a buffer that the version string will be put in. bufferlen - maximum length of version string (size of buffer). RESULT length - length of actual string returned. SEE ALSO sndfile.library/SF_OpenRead sndfile.library/SF_OpenRead NAME SF_OpenRead - Open the specified file for read. SYNOPSIS sfptr = SF_OpenRead(path, wfinfo) A0 A1 SNDFILE* SF_OpenRead(const char *, SF_INFO *); FUNCTION Open the specified file for read and fill in SF_INFO structure. NOTE When RAW files are opened, the SF_INFO structure will be used to determine bitwidth etc, so always fill in some defaults... EXAMPLE SNDFILE *sfptr; SF_INFO wfinfo; wfinfo.seekable = TRUE; wfinfo.samplerate = 44100; wfinfo.pcmbitwidth = 16; wfinfo.channels = 2; wfinfo.format = SF_FORMAT_RAW_BE; sfptr = SF_OpenRead("Work:Test.aiff", &wfinfo); INPUTS path - full path to inputfile. wfinfo - pointer to SF_INFO structure. RESULT sfptr - pointer to use in all subsequent sndfile-operations on file. NULL on error. SEE ALSO SF_OpenWrite() sndfile.library/SF_OpenWrite sndfile.library/SF_OpenWrite NAME SF_OpenWrite - Open the specified file for write. SYNOPSIS sfptr = SF_OpenWrite(path, wfinfo) A0 A1 SNDFILE* SF_OpenWrite(const char *, const SF_INFO *); FUNCTION Open the specified file for write using the SF_INFO structure. NOTE For encoded formats (ie u-law, A-law and ADPCM), pcmbitwidth is the bit width before encoding or after decoding. EXAMPLE SNDFILE *sfptr; SF_INFO wfinfo; wfinfo.samplerate = 44100; wfinfo.pcmbitwidth = 16; wfinfo.channels = 2; wfinfo.format = SF_FORMAT_AIFF | SF_FORMAT_PCM; sfptr = SF_OpenWrite("RAM:Test.aiff", &wfinfo); INPUTS path - full path to outputfile. wfinfo - pointer to SF_INFO structure. RESULT sfptr - pointer to use in all subsequent sndfile-operations on file. NULL on error. SEE ALSO SF_OpenRead() sndfile.library/SF_Close sndfile.library/SF_Close NAME SF_Close - Close a previously opened file. SYNOPSIS success = SF_Close(sndfile) A0 int SF_Close(SNDFILE *); FUNCTION Close a previously opened file. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. RESULT success - 0 for success or an error value. SEE ALSO SF_OpenRead(), SF_OpenWrite() sndfile.library/SF_ReadRaw sndfile.library/SF_ReadRaw NAME SF_ReadRaw - Read raw data from file. SYNOPSIS length = SF_ReadRaw(sndfile, ptr, bytes) A0 A1 D0 size_t SF_ReadRaw(SNDFILE *, void *, size_t); FUNCTION Read raw data (don't expect this to be audio) from file. The number of bytes read 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. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a buffer that the data will be put in. bytes - number of bytes to read (size of buffer). RESULT length - number of bytes read or -1 if an error occurred. SEE ALSO SF_WriteRaw() sndfile.library/SF_WriteRaw sndfile.library/SF_WriteRaw NAME SF_WriteRaw - Write raw data to file. SYNOPSIS length = SF_WriteRaw(sndfile, ptr, bytes) A0 A1 D0 size_t SF_WriteRaw(SNDFILE *, void *, size_t); FUNCTION Write raw data to file. The number of bytes 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. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a buffer that contains the data to be written. bytes - number of bytes to write (size of buffer). RESULT length - number of bytes read or -1 if an error occurred. SEE ALSO SF_ReadRaw() sndfile.library/SF_ReadChar sndfile.library/SF_ReadChar NAME SF_ReadChar - Not implemented yet. SEE ALSO SF_WriteChar(), SF_ReadFChar(), SF_WriteFChar() sndfile.library/SF_WriteChar sndfile.library/SF_WriteChar NAME SF_WriteChar - Not implemented yet. SEE ALSO SF_ReadChar(), SF_ReadFChar(), SF_WriteFChar() sndfile.library/SF_ReadShort sndfile.library/SF_ReadShort NAME SF_ReadShort - Read audio data from file. SYNOPSIS length = SF_ReadShort(sndfile, ptr, items) A0 A1 D0 size_t SF_ReadShort(SNDFILE *, short *, size_t); FUNCTION Reads audio data and fills buffer with signed 16bit values. NOTE The items parameter must be an integer product of the number of channels or an error will occur. EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a signed short array that the data will be put in. items - number of items to read (size of buffer (in 16bit)). RESULT length - number of items read or -1 if an error occurred. BUGS Version 1 of the library does not return values from files with another bitwidth correctly, this will be fixed in version 2. In the meantime I suggest a kludge (see sfplay.c)... SEE ALSO SF_WriteShort(), SF_ReadFShort(), SF_WriteFShort() sndfile.library/SF_WriteShort sndfile.library/SF_WriteShort NAME SF_WriteShort - Write audio data to file. SYNOPSIS length = SF_WriteShort(sndfile, ptr, items) A0 A1 D0 size_t SF_WriteShort(SNDFILE *, short *, size_t); FUNCTION Writes audio data to file from buffer with signed 16bit values. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a signed short array that contains the data to be written. items - number of items to write (size of buffer (in 16bit)). RESULT length - number of items written or -1 if an error occurred. SEE ALSO SF_ReadShort(), SF_ReadFShort(), SF_WriteFShort() sndfile.library/SF_ReadInt sndfile.library/SF_ReadInt NAME SF_ReadInt - Read audio data from file. SYNOPSIS length = SF_ReadInt(sndfile, ptr, items) A0 A1 D0 size_t SF_ReadInt(SNDFILE *, int *, size_t); FUNCTION Reads audio data and fills buffer with signed 32bit values. NOTE The items parameter must be an integer product of the number of channels or an error will occur. EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a signed int array that the data will be put in. items - number of items to read (size of buffer (in 32bit)). RESULT length - number of items read or -1 if an error occurred. BUGS Version 1 of the library does not return values from files with another bitwidth correctly, this will be fixed in version 2. SEE ALSO SF_WriteInt(), SF_ReadFInt(), SF_WriteFInt() sndfile.library/SF_WriteInt sndfile.library/SF_WriteInt NAME SF_WriteInt - Write audio data to file. SYNOPSIS length = SF_WriteInt(sndfile, ptr, items) A0 A1 D0 size_t SF_WriteInt(SNDFILE *, int *, size_t); FUNCTION Writes audio data to file from buffer with signed 32bit values. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a signed int array that contains the data to be written. items - number of items to write (size of buffer (in 32bit)). RESULT length - number of items written or -1 if an error occurred. SEE ALSO SF_ReadInt(), SF_ReadFInt(), SF_WriteFInt() sndfile.library/SF_ReadDouble sndfile.library/SF_ReadDouble NAME SF_ReadDouble - Read audio data from file. SYNOPSIS length = SF_ReadDouble(sndfile, ptr, items, normalize) A0 A1 D0 D1 size_t SF_ReadDouble(SNDFILE *, double *, size_t, int); FUNCTION Reads audio data and fills buffer with 64bit float values. If normalize is 1, the read operation will return data that is normalized so that the maximum possible full scale sample value of the file on disk will result in a sample value of 1.0 in the array, with all other sample values scaled accordingly. NOTE The items parameter must be an integer product of the number of channels or an error will occur. EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a double array that the data will be put in. items - number of items to read (size of buffer (in 64bit)). normalize - boolean to select normalization. RESULT length - number of items read or -1 if an error occurred. BUGS Version 1 of the library does not return values from files with another bitwidth correctly, this will be fixed in version 2. SEE ALSO SF_WriteDouble(), SF_ReadFDouble(), SF_WriteFDouble() sndfile.library/SF_WriteDouble sndfile.library/SF_WriteDouble NAME SF_WriteDouble - Write audio data to file. SYNOPSIS length = SF_WriteDouble(sndfile, ptr, items, normalize) A0 A1 D0 D1 size_t SF_WriteDouble(SNDFILE *, double *, size_t, int); FUNCTION Writes audio data to file from buffer with 64bit float values. If normalize is 1, the write operation will assume that data in the array is normalize so that all values are between -1 and 1 and will scale the samples to fill the bitwidth of the disk file format. If normalize is zero, no scaling will take place and the samples will be truncated and written to disk as integers of 8, 16, 24 or 32 bits. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a double array that contains the data to be written. items - number of items to write (size of buffer (in 64bit)). normalize - boolean to select normalization. RESULT length - number of items written or -1 if an error occurred. SEE ALSO SF_ReadDouble(), SF_ReadFDouble(), SF_WriteFDouble() sndfile.library/SF_ReadFChar sndfile.library/SF_ReadFChar NAME SF_ReadFChar - Not implemented yet. SEE ALSO SF_WriteFChar(), SF_ReadChar(), SF_WriteChar() sndfile.library/SF_WriteFChar sndfile.library/SF_WriteFChar NAME SF_WriteFChar - Not implemented yet. SEE ALSO SF_ReadFChar(), SF_ReadChar(), SF_WriteChar() sndfile.library/SF_ReadFShort sndfile.library/SF_ReadFShort NAME SF_ReadFShort - Read audio data from file. SYNOPSIS length = SF_ReadFShort(sndfile, ptr, frames) A0 A1 D0 size_t SF_ReadFShort(SNDFILE *, short *, size_t); FUNCTION Reads audio data and fills buffer with signed 16bit values. NOTE The array must be large enough to hold the product of frames and the number of channels. EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a signed short array that the data will be put in. frames - number of frames to read (size of buffer (in 16bit) / channels). RESULT length - number of frames read or -1 if an error occurred. BUGS Version 1 of the library does not return values from files with another bitwidth correctly, this will be fixed in version 2. SEE ALSO SF_WriteFShort(), SF_ReadShort(), SF_WriteShort() sndfile.library/SF_WriteFShort sndfile.library/SF_WriteFShort NAME SF_WriteFShort - Write audio data to file. SYNOPSIS length = SF_WriteFShort(sndfile, ptr, frames) A0 A1 D0 size_t SF_WriteFShort(SNDFILE *, short *, size_t); FUNCTION Writes audio data to file from buffer with signed 16bit values. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a signed short array that contains the data to be written. frames - number of frames to write (size of buffer (in 16bit) / channels). RESULT length - number of frames written or -1 if an error occurred. SEE ALSO SF_ReadFShort(), SF_ReadShort(), SF_WriteShort() sndfile.library/SF_ReadFInt sndfile.library/SF_ReadFInt NAME SF_ReadFInt - Read audio data from file. SYNOPSIS length = SF_ReadFInt(sndfile, ptr, frames) A0 A1 D0 size_t SF_ReadFInt(SNDFILE *, int *, size_t); FUNCTION Reads audio data and fills buffer with signed 32bit values. NOTE The array must be large enough to hold the product of frames and the number of channels. EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a signed int array that the data will be put in. frames - number of frames to read (size of buffer (in 32bit) / channels). RESULT length - number of frames read or -1 if an error occurred. BUGS Version 1 of the library does not return values from files with another bitwidth correctly, this will be fixed in version 2. SEE ALSO SF_WriteFInt(), SF_ReadInt(), SF_WriteInt() sndfile.library/SF_WriteFInt sndfile.library/SF_WriteFInt NAME SF_WriteFInt - Write audio data to file. SYNOPSIS length = SF_WriteFInt(sndfile, ptr, frames) A0 A1 D0 size_t SF_WriteFInt(SNDFILE *, int *, size_t); FUNCTION Writes audio data to file from buffer with signed 32bit values. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a signed int array that contains the data to be written. frames - number of frames to write (size of buffer (in 32bit) / channels). RESULT length - number of frames written or -1 if an error occurred. SEE ALSO SF_ReadFInt(), SF_ReadInt(), SF_WriteInt() sndfile.library/SF_ReadFDouble sndfile.library/SF_ReadFDouble NAME SF_ReadFDouble - Read audio data from file. SYNOPSIS length = SF_ReadFDouble(sndfile, ptr, frames, normalize) A0 A1 D0 D1 size_t SF_ReadFDouble(SNDFILE *, double *, size_t, int); FUNCTION Reads audio data and fills buffer with 64bit float values. If normalize is 1, the read operation will return data that is normalized so that the maximum possible full scale sample value of the file on disk will result in a sample value of 1.0 in the array, with all other sample values scaled accordingly. NOTE The array must be large enough to hold the product of frames and the number of channels. EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a double array that the data will be put in. frames - number of frames to read (size of buffer (in 64bit) / channels). normalize - boolean to select normalization. RESULT length - number of frames read or -1 if an error occurred. BUGS Version 1 of the library does not return values from files with another bitwidth correctly, this will be fixed in version 2. SEE ALSO SF_WriteFDouble(), SF_ReadDouble(), SF_WriteDouble() sndfile.library/SF_WriteFDouble sndfile.library/SF_WriteFDouble NAME SF_WriteFDouble - Write audio data to file. SYNOPSIS length = SF_WriteFDouble(sndfile, ptr, frames, normalize) A0 A1 D0 D1 size_t SF_WriteFDouble(SNDFILE *, double *, size_t, int); FUNCTION Writes audio data to file from buffer with 64bit float values. If normalize is 1, the write operation will assume that data in the array is normalize so that all values are between -1 and 1 and will scale the samples to fill the bitwidth of the disk file format. If normalize is zero, no scaling will take place and the samples will be truncated and written to disk as integers of 8, 16, 24 or 32 bits. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. ptr - pointer to a double array that contains the data to be written. frames - number of frames to write (size of buffer (in 64bit) / channels). normalize - boolean to select normalization. RESULT length - number of frames written or -1 if an error occurred. SEE ALSO SF_ReadFDouble(), SF_ReadDouble(), SF_WriteDouble() sndfile.library/SF_Seek sndfile.library/SF_Seek NAME SF_Seek - Seek within the waveform data of file. SYNOPSIS offset = SF_Seek(sndfile, frames, whence) A0 D0 D1 off_t SF_Seek(SNDFILE *, off_t, int); FUNCTION The file seek functions work much like lseek in stdio.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) samples or frames. Therefore, for 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. Valid values for the whence parameter are defined to be the same as the lseek function and behave as follows: SEEK_SET - The offset is set to the start of the audio data plus offset (multichannel) samples. SEEK_CUR - The offset is set to its current location plus offset (multichannel) samples. SEEK_END - The offset is set to the end of the data plus offset (multichannel) samples. NOTE Frames offset can be negative and in fact should be when SEEK_END is used for the whence parameter. EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. frames - number of audio frames to seek. whence - position to seek from. RESULT offset - offset in (multichannel) samples from the start of the audio data or -1 if an error occurred (f.ex. seeking past file limits). SEE ALSO sndfile.library/SF_FormatCheck sndfile.library/SF_FormatCheck NAME SF_FormatCheck - Check if SF_INFO structure is valid. SYNOPSIS valid = SF_FormatCheck(info) A0 int SF_FormatCheck(const SF_INFO *); FUNCTION Check if combination of values in SF_INFO structure field are valid. NOTE EXAMPLE INPUTS info - pointer to a filled in SF_INFO structure. RESULT valid - TRUE if valid. SEE ALSO sndfile.library/SF_SignalMax sndfile.library/SF_SignalMax NAME SF_SignalMax - Scan file for maximum absolute sample value. SYNOPSIS maxval = SF_SignalMax(sndfile) A0 double* SF_SignalMax(SNDFILE *); FUNCTION Scan file for maximum absolute sample value. NOTE EXAMPLE INPUTS sndfile - previously allocated SNDFILE pointer. RESULT maxval - maximum absolute sample value. SEE ALSO sndfile.library/SF_GetHeaderInfo sndfile.library/SF_GetHeaderInfo NAME SF_GetHeaderInfo - Get info on file. SYNOPSIS length = SF_GetHeaderInfo(sndfile, buffer, bufferlen, offset) A0 A1 D0 D1 size_t SF_GetHeaderInfo(SNDFILE *, char *, size_t, size_t); FUNCTION Fill in the provided buffer with info on the audio file. NOTE EXAMPLE len = SF_GetHeaderInfo(sndfile, buf, sizeof(buf), 0); INPUTS sndfile - previously allocated SNDFILE pointer. buffer - pointer to a buffer that the version string will be put in. bufferlen - maximum length of version string (size of buffer). offset - offset in info to copy from RESULT length - length of actual string returned. SEE ALSO sndfile.library/SF_ErrorStr sndfile.library/SF_ErrorStr NAME SF_ErrorStr - Get current error-message. SYNOPSIS error = SF_ErrorStr(sndfile, buffer, bufferlen) A0 A1 D0 int SF_ErrorStr(SNDFILE *, char *, size_t); FUNCTION Fill in the provided buffer with current error-message. NOTE EXAMPLE int sf_perror(SNDFILE *sndfile) { int ret; char str[256]; ret = SF_ErrorStr(sndfile, str, sizeof(str)); printf("%s\n", str); return ret; } INPUTS sndfile - previously allocated SNDFILE pointer. buffer - pointer to a buffer that the error-message will be put in. bufferlen - maximum length of error-message (size of buffer). RESULT error - SFE_NO_ERROR if everything went well. SEE ALSO SF_ErrorNumber() sndfile.library/SF_ErrorNumber sndfile.library/SF_ErrorNumber NAME SF_ErrorNumber - Get error-message related to number. SYNOPSIS error = SF_ErrorNumber(errnum, buffer, bufferlen) D1 A1 D0 int SF_ErrorStr(int, char *, size_t); FUNCTION Fill in the provided buffer with error-message related to number. NOTE EXAMPLE INPUTS errnum - error number. buffer - pointer to a buffer that the error-message will be put in. bufferlen - maximum length of error-message (size of buffer). RESULT error - SFE_NO_ERROR if everything went well. SEE ALSO SF_ErrorStr()