Provided by: libsox-dev_14.0.0-5_i386 bug

NAME

       libsox - SoX, an audio file-format and effect library

SYNOPSIS

       #include <sox.h>

       int sox_format_init(void);

       ft_t sox_open_read(const char *path, const sox_signalinfo_t *info, const char *filetype);

       ft_t sox_open_write(sox_bool (*overwrite_permitted)(const char *filename), const char *path, const sox_signalinfo_t *info, const char *filetype, const char *comment, sox_size_t length, const sox_instrinfo_t *instr, const sox_loopinfo_t *loops);

       sox_size_t sox_read(ft_t ft, sox_ssample_t *buf, sox_size_t len);

       sox_size_t sox_write(ft_t ft, sox_ssample_t *buf, sox_size_t len);

       int sox_close(ft_t ft);

       int sox_seek(ft_t ft, sox_size_t offset, int whence);

       sox_effect_handler_t const *sox_find_effect(char const *name);

       void sox_create_effect(sox_effect_t effp, sox_effect_handler_t const *e);

       int sox_get_effect(sox_effect_t effp, const char *name);

       int sox_update_effect(eff_t effp, const sox_signalinfo_t *in, const sox_signalinfo_t *out, int effect_mask);

       cc file.c -o file lsox

DESCRIPTION

       libsox  is  a  library  of sound sample file format readers/writers and
       sound effects processors. It is mainly developed for use by SoX but  is
       useful for any sound application.

       sox_format_init  function performs some required initialization related
       to all file format handlers.  If compiled with dynamic library  support
       then  this  will  detect  and  initialize all external libraries.  This
       should be called before any other file operations are performed.

       sox_open_input function opens the file for reading whose  name  is  the
       string  pointed  to  by path and associates an ft_t with it. If info is
       non-NULL then it will be used to specify the data format of  the  input
       file. This is normally only needed for headerless audio files since the
       information is not stored in the file. If filetype is non-NULL then  it
       will  be  used  to specify the file type. If this is not specified then
       the file type is attempted to be derived by looking at the file  header
       and/or  the  filename  extension.  A special name of "-" can be used to
       read data from stdin.

       sox_open_output function opens the file for writing whose name  is  the
       string  pointed  to  by path and associates an ft_t with it. If info is
       non-NULL then it will be used to specify the data format of the  output
       file. Since most file formats can write data in different data formats,
       this generally has to be specified. The info structure from  the  input
       format  handler  can be specified to copy data over in the same format.
       If comment is non-NULL, it will be  written  in  the  file  header  for
       formats  that support comments. If filetype is non-NULL then it will be
       used to specify the file type. If this is not specified then  the  file
       type is attempted to be derived by looking at the filename extension. A
       special name of "-" can be used to write data to stdout.

       The function sox_read reads len samples in  to  buf  using  the  format
       handler  specified  by  ft. All data read is converted to 32-bit signed
       samples before being placed in to buf. The value of len is specified in
       total  samples.  If  its value is not evenly divisable by the number of
       channels, undefined behavior will occur.

       The function sox_write writes len samples from  buf  using  the  format
       handler  specified by ft. Data in buf must be 32-bit signed samples and
       will be converted during  the  write  process.  The  value  of  len  is
       specified in total samples. If its value is not evenly divisable by the
       number of channels, undefined behavior will occur.

       The sox_close function dissociates the named ft_t from  its  underlying
       file  or  set  of  functions.  If the format handler was being used for
       output, any buffered data is written first.

       sox_format_quite function performs some required cleanup related to all
       file format handlers.

       The  function sox_find_effect finds effect name, returning a pointer to
       its sox_effect_handler_t if it exists, and NULL otherwise.

       The  function  sox_create_effect  instantiates   an   effect   into   a
       sox_effect_t  given  a  sox_effect_handler_t *. Any missing methods are
       automatically set to the corresponding nothing method.

       The sox_update_effect function copies input and output signal info into
       effect structures. The effect_mask parameter is the return value of the
       previous call to this  function;  for  the  first  call,  pass  0.  The
       function returns the updated effect mask.

       SoX  includes  skeleton  C  files  to assist you in writing new formats
       (skelform.c) and effects (skeleff.c). sox.c itself is a  good  starting
       point  for new programs. Note that new formats can often just deal with
       the header and then use raw.c’s routines for reading and writing.

RETURN VALUE

       Upon successful completion sox_open_input and sox_open_output return an
       ft_t  (which  is a pointer).  Otherwise, NULL is returned. TODO: Need a
       way to return reason for failures. Currently,  relies  on  sox_warn  to
       print information.

       sox_read  and  sox_write return the number of samples successfully read
       or written. If an error occurs, or  the  end-of-file  is  reached,  the
       return  value is a short item count or SOX_EOF. TODO: sox_read does not
       distiguish between end-of-file and error. Need an feof()  and  ferror()
       concept to determine which occured.

       Upon  successful  completion sox_close returns 0. Otherwise, SOX_EOF is
       returned. In either case, any further access (including another call to
       sox_close()) to the handler results in undefined behavior. TODO: Need a
       way to return reason for failures. Currently,  relies  on  sox_warn  to
       print information.

       Upon  successful  completion  sox_seek returns 0. Otherwise, SOX_EOF is
       returned. TODO Need to set a global error and implement sox_tell.

ERRORS

       TODO

INTERNALS

       SoX’s formats and effects operate  on  an  internal  buffer  format  of
       signed  32-bit  longs.  The  data  processing  routines are called with
       buffers of these samples, and buffer sizes which refer to the number of
       samples  processed, not the number of bytes. File readers translate the
       input samples to signed  32-bit  integers  and  return  the  number  of
       samples  read.  For example, data in linear signed byte format is left-
       shifted 24 bits.

       This does cause problems in processing the data.  For example:
            *obuf++ = (*ibuf++ + *ibuf++)/2;
       would not mix down left and right channels into one monophonic channel,
       because  the  resulting  samples  would overflow 32 bits.  Instead, the
       ‘‘avg’’ effects must use:
            *obuf++ = *ibuf++/2 + *ibuf++/2;

       Stereo data  is  stored  with  the  left  and  right  speaker  data  in
       successive  samples.   Quadraphonic  data is stored in this order: left
       front, right front, left rear, right rear.

FORMATS

       A format is responsible for translating between sound sample files  and
       an  internal buffer.  The internal buffer is store in signed longs with
       a fixed sampling rate.  The format operates from two data structures: a
       format structure, and a private structure.

       The  format  structure  contains  a  list of control parameters for the
       sample: sampling  rate,  data  size  (8,  16,  or  32  bits),  encoding
       (unsigned, signed, floating point, etc.), number of sound channels.  It
       also contains other state information: whether the sample file needs to
       be  byte-swapped,  whether  sox_seek()  will work, its suffix, its file
       stream pointer, its format pointer, and the private structure  for  the
       format .

       The  private  area  is just a preallocated data array for the format to
       use however it wishes.  It should have a  defined  data  structure  and
       cast  the  array to that structure.  See voc.c for the use of a private
       data area.  Voc.c has to track the number of samples it writes and when
       finishing,  seek  back  to  the beginning of the file and write it out.
       The private area is  not  very  large.   The  ‘‘echo’’  effect  has  to
       malloc() a much larger area for its delay line buffers.

       A format has 6 routines:

       startread           Set  up  the  format  parameters, or read in a data
                           header, or do what needs to be done.

       read                Given a buffer and a length: read up to  that  many
                           samples,  transform them into signed long integers,
                           and copy them into the buffer.  Return  the  number
                           of samples actually read.

       stopread            Do what needs to be done.

       startwrite          Set  up  the format parameters, or write out a data
                           header, or do what needs to be done.

       write               Given a buffer and a length: copy that many samples
                           out  of  the buffer, convert them from signed longs
                           to the appropriate data,  and  write  them  to  the
                           file.  If it can’t write out all the samples, fail.

       stopwrite           Fix up any file header, or  do  what  needs  to  be
                           done.

EFFECTS

       An  effects  loop  has  one  input  and  one  output  stream.  It has 5
       routines.

       getopts             is called with a character string argument list for
                           the effect.

       start               is  called with the signal parameters for the input
                           and output streams.

       flow                is called with input and output data  buffers,  and
                           (by  reference)  the  input  and output data buffer
                           sizes.  It processes  the  input  buffer  into  the
                           output  buffer,  and sets the size variables to the
                           numbers of samples actually processed.  It is under
                           no  obligation  to  read  from  the input buffer or
                           write to the output buffer during  the  same  call.
                           If  the  call  returns  SOX_EOF then this should be
                           used as an indication  that  this  effect  will  no
                           longer  read  any data and can be used to switch to
                           drain mode sooner.

       drain               is called  after  there  are  no  more  input  data
                           samples.   If  the  effect  wishes to generate more
                           data samples it copies the generated  data  into  a
                           given  buffer  and  returns  the  number of samples
                           generated.  If it fills  the  buffer,  it  will  be
                           called  again,  etc.   The echo effect uses this to
                           fade away.

       stop                is called when there are no more input  samples  to
                           process.   stop  may generate output samples on its
                           own.  See echo.c for how to do this, and  see  that
                           what it does is absolutely bogus.

BUGS

       This manual page is both incomplete and out of date.

SEE ALSO

       sox(1), soxexam(7)

LICENSE

       Copyright  1991  Lance  Norskog  and  Sundry  Contributors.   Copyright
       1998-2007 by Chris Bagwell and SoX Contributors.

       This library is free software; you can redistribute it and/or modify it
       under  the  terms of the GNU Lesser General Public License as published
       by the Free Software  Foundation;  either  version  2.1,  or  (at  your
       option) any later version.

       This  library  is  distributed  in the hope that it will be useful, but
       WITHOUT  ANY  WARRANTY;  without   even   the   implied   warranty   of
       MERCHANTABILITY  or  FITNESS  FOR  A  PARTICULAR  PURPOSE.  See the GNU
       Lesser General Public License for more details.

AUTHORS

       Chris  Bagwell  (cbagwell@users.sourceforge.net).   Other  authors  and
       contributors  are  listed  in the AUTHORS file that is distributed with
       the source code.

                               January 31, 2007                         SoX(3)