Provided by: sox_14.3.0-1.1build1_i386 bug


       SoX - Sound eXchange, the Swiss Army knife of audio manipulation


       This  manual  describes  SoX  supported  file  formats and audio device
       types; the SoX manual set starts with sox(1).

       Format types that can SoX can determine by  a  filename  extension  are
       listed  with  their  names  preceded  by  a dot.  Format types that are
       optionally built into SoX are marked ‘(optional)’.

       Format types that can be handled by an external library via an optional
       pseudo  file  type (currently sndfile or ffmpeg) are marked e.g. ‘(also
       with -t sndfile)’.  This might be  useful  if  you  have  a  file  that
       doesn’t work with SoX’s default format readers and writers, and there’s
       an external reader or writer for that format.

       To see if SoX has support for an optional format or device,  enter  sox
       -h and look for its name under the list: ‘AUDIO FILE FORMATS’ or ‘AUDIO

       .raw (also with -t sndfile), .f32, .f64, .s8, .s16, .s24, .s32,
       .u8, .u16, .u24, .u32, .ul, .al, .lu, .la
              Raw (headerless) audio files.  For raw, the sample rate and  the
              data  encoding  must be given using command-line format options;
              for the other listed types, the sample  rate  defaults  to  8kHz
              (but may be overridden), and the data encoding is defined by the
              given suffix.  Thus f32 and f64 indicate files encoded as 32 and
              64-bit  (IEEE  single  and  double precision) floating point PCM
              respectively; s8, s16, s24, and s32  indicate  8,  16,  24,  and
              32-bit  signed  integer  PCM respectively; u8, u16, u24, and u32
              indicate  8,  16,  24,   and   32-bit   unsigned   integer   PCM
              respectively; ul indicates ‘μ-law’ (8-bit), al indicates ‘A-law’
              (8-bit), and lu and la are inverse bit order ‘μ-law’ and inverse
              bit order ‘A-law’ respectively.  For all raw formats, the number
              of channels defaults to 1 (but may be overridden).

              Headerless audio files on a SPARC computer are likely to  be  of
              format  ul;  on a Mac, they’re likely to be u8 but with a sample
              rate of 11025 or 22050 Hz.

              See .ima and .vox for raw ADPCM formats, and .cdda  for  raw  CD
              digital audio.

       .f4, .f8, .s1, .s2, .s3, .s4,
       .u1, .u2, .u3, .u4, .sb, .sw, .sl, .ub, .uw
              Deprecated aliases for f32, f64, s8, s16, s24, s32,
              u8, u16, u24, u32, s8, s16, s32, u8, and u16 respectively.

       .8svx (also with -t sndfile)
              Amiga 8SVX musical instrument description format.

       .aiff, .aif (also with -t sndfile)
              AIFF  files  as  used on old Apple Macs, Apple IIc/IIgs and SGI.
              SoX’s AIFF support does not include multiple  audio  chunks,  or
              the  8SVX musical instrument description format.  AIFF files are
              multimedia archives and can  have  multiple  audio  and  picture
              chunks  -  you  may  need a separate archiver to work with them.
              With Mac OS X, AIFF has been superseded by CAF.

       .aiffc, .aifc (also with -t sndfile)
              AIFF-C is a format based on  AIFF  that  was  created  to  allow
              handling  compressed  audio.   It  can also handle little endian
              uncompressed linear data that  is  often  referred  to  as  sowt
              encoding.   This  encoding  has  also  become the defacto format
              produced by modern Macs as  well  as  iTunes  on  any  platform.
              AIFF-C  files  produced by other applications typically have the
              file extension .aif and require looking at its header to  detect
              the  true  format.   The sowt encoding is the only encoding that
              SoX can handle with this format.

              AIFF-C is defined in DAVIC 1.4 Part 9 Annex B.  This  format  is
              referred from ARIB STD-B24, which is specified for Japanese data
              broadcasting.  Any private chunks are not supported.

       alsa (optional)
              Advanced Linux Sound Architecture device driver;  supports  both
              playing  and  recording audio.  ALSA is only used in Linux-based
              operating systems, though these often support OSS (see below) as
              well.  Examples:

                   sox infile -t alsa
                   sox infile -t alsa default
                   sox infile -t alsa plughw:0,0
                   sox -2 -t alsa hw:1 outfile

              See also play(1) and rec(1).

       .amb   Ambisonic  B-Format: a specialisation of .wav with between 3 and
              16 channels of audio for use with  an  Ambisonic  decoder.   See
              for details.  It is up to the user to get the channels  together
              in the right order and at the correct amplitude.

       .amr-nb (optional)
              Adaptive  Multi  Rate - Narrow Band speech codec; a lossy format
              used in 3rd generation mobile telephony and defined in  3GPP  TS
              26.071 et al.

              AMR-NB  audio  has  a  fixed sampling rate of 8 kHz and supports
              encoding to the following  bit-rates  (as  selected  by  the  -C
              option):  0  = 4.75 kbit/s, 1 = 5.15 kbit/s, 2 = 5.9 kbit/s, 3 =
              6.7 kbit/s, 4 = 7.4 kbit/s 5 = 7.95 kbit/s, 6 = 10.2 kbit/s, 7 =
              12.2 kbit/s.

       .amr-wb (optional)
              Adaptive  Multi  Rate  -  Wide Band speech codec; a lossy format
              used in 3rd generation mobile telephony and defined in  3GPP  TS
              26.171 et al.

              AMR-WB  audio  has  a fixed sampling rate of 16 kHz and supports
              encoding to the following  bit-rates  (as  selected  by  the  -C
              option):  0 = 6.6 kbit/s, 1 = 8.85 kbit/s, 2 = 12.65 kbit/s, 3 =
              14.25 kbit/s, 4 = 15.85 kbit/s 5  =  18.25  kbit/s,  6  =  19.85
              kbit/s, 7 = 23.05 kbit/s, 8 = 23.85 kbit/s.

       ao (optional)
    ’s  Audio  Output  device driver; works only for playing
              audio.  It supports a wide range of devices and sound systems  -
              see  its  documentation  for the full range.  For the most part,
              SoX’s use of libao cannot be configured directly; instead, libao
              configuration files must be used.

              The  filename  specified is used to determine which libao plugin
              to use.  Normally, you should specify ‘default’ as the filename.
              If  that  doesn’t give the desired behavior then you can specify
              the short name for a given plugin (such as pulse for pulse audio
              plugin).  Examples:

                   sox infile -t ao
                   sox infile -t ao default
                   sox infile -t ao pulse

              See also play(1).

       .au, .snd (also with -t sndfile)
              Sun Microsystems AU files.  There are many types of AU file; DEC
              has invented its own with a  different  magic  number  and  byte
              order.   To  write a DEC file, use the -L option with the output
              file options.

              Some .au files are known to have invalid AU headers;  these  are
              probably  original Sun μ-law 8000 Hz files and can be dealt with
              using the .ul format (see below).

              It is possible to override AU file header information  with  the
              -r  and  -c  options,  in which case SoX will issue a warning to
              that effect.

       .avr   Audio Visual Research format; used by  a  number  of  commercial
              packages on the Mac.

       .caf (optional)
              Apple’s Core Audio File format.

       .cdda, .cdr
              ‘Red Book’ Compact Disc Digital Audio (raw audio).  CDDA has two
              audio  channels  formatted  as  16-bit  signed   integers   (big
              endian)at  a  sample  rate  of 44.1 kHz.  The number of (stereo)
              samples in each CDDA track is always a multiple of 588.

       coreaudio (optional)
              Mac OSX CoreAudio  device  driver:  supports  both  playing  and
              recording audio.  Examples:

                   sox infile -t coreaudio
                   sox infile -t coreaudio default

              See also play(1) and rec(1).

       .cvsd, .cvs
              Continuously  Variable  Slope  Delta  modulation.   A headerless
              format used to compress speech audio for  applications  such  as
              voice  mail.   This  format  is sometimes used with bit-reversed
              samples - the -X format option can be used to set the bit-order.

       .cvu   Continuously Variable Slope Delta modulation (unfiltered).  This
              is an alternative handler for CVSD that is unfiltered but can be
              used with any bit-rate.  E.g.

                   sox infile outfile.cvu rate 28k
                   play -r 28k outfile.cvu sinc -3.4k

       .dat   Text  Data  files.  These files contain a textual representation
              of the sample data.  There is one line  at  the  beginning  that
              contains  the sample rate.  Subsequent lines contain two numeric
              data items: the time since the beginning of the first sample and
              the sample value.  Values are normalized so that the maximum and
              minimum are 1 and -1.  This file format can be  used  to  create
              data  files for external programs such as FFT analysers or graph
              routines.  SoX can also convert a file in this format back  into
              one of the other file formats.

       .dvms, .vms
              Used  in  Germany  to  compress  speech audio for voice mail.  A
              self-describing variant of cvsd.

       .fap (optional)
              See .paf.

       ffmpeg (optional)
              This is a pseudo-type that forces ffmpeg to be used. The  actual
              file  type  is  deduced from the file name (it cannot be used on
              stdio).  It can read a wide range of audio  files,  not  all  of
              which  are  documented  here,  and  also the audio track of many
              video files (including AVI, WMV and MPEG). At present  only  the
              first audio track of a file can be read.

       .flac (optional; also with -t sndfile)
    ’s  Free Lossless Audio CODEC compressed audio.  FLAC is
              an open, patent-free CODEC designed for compressing  music.   It
              is  similar  to  MP3  and Ogg Vorbis, but lossless, meaning that
              audio is compressed in FLAC without any loss in quality.

              SoX can read native FLAC files (.flac) but not  Ogg  FLAC  files
              (.ogg).  [But see .ogg below for information relating to support
              for Ogg Vorbis files.]

              SoX can write native FLAC files according to a given or  default
              compression level.  8 is the default compression level and gives
              the best (but slowest)  compression;  0  gives  the  least  (but
              fastest)  compression.   The compression level is selected using
              the -C option [see sox(1)] with a whole number from 0 to 8.

       .fssd  An alias for the .u8 format.

       .gsm (optional; also with -t sndfile)
              GSM  06.10  Lossy  Speech  Compression.   A  lossy  format   for
              compressing  speech  which  is  used  in the Global Standard for
              Mobile telecommunications (GSM).  It’s  good  for  its  purpose,
              shrinking  audio  data size, but it will introduce lots of noise
              when a given audio signal is encoded and decoded multiple times.
              This  format  is  used  by  some voice mail applications.  It is
              rather CPU intensive.

       .hcom  Macintosh HCOM files.  These are Mac  FSSD  files  with  Huffman

       .htk   Single  channel  16-bit  PCM  format  used by HTK, a toolkit for
              building Hidden Markov Model speech processing tools.

       .ircam (also with -t sndfile)
              Another name for .sf.

       .ima (also with -t sndfile)
              A headerless file of IMA ADPCM  audio  data.  IMA  ADPCM  claims
              16-bit  precision packed into only 4 bits, but in fact sounds no
              better than .vox.

       .lpc, .lpc10
              LPC-10 is a compression  scheme  for  speech  developed  in  the
              United   States.   See  for
              details.  There  is  no  associated  file   format,   so   SoX’s
              implementation is headerless.

       .mat, .mat4, .mat5 (optional)
              Matlab 4.2/5.0 (respectively GNU Octave 2.0/2.1) format (.mat is
              the same as .mat4).

       .m3u   A playlist format; contains a list  of  audio  files.   SoX  can
              read,  but  not  write this file format.  See [1] for details of
              this format.

       .maud  An IFF-conforming audio file type, registered by MS  MacroSystem
              Computer  GmbH, published along with the ‘Toccata’ sound-card on
              the Amiga.  Allows 8bit linear, 16bit linear,  A-Law,  μ-law  in
              mono and stereo.

       .mp3, .mp2 (optional read, optional write)
              MP3  compressed  audio;  MP3  (MPEG  Layer  3)  is a part of the
              patent-encumbered   MPEG   standards   for   audio   and   video
              compression.   It  is  a  lossy compression format that achieves
              good compression rates with little quality loss.

              Because MP3 is patented, SoX  cannot  be  distributed  with  MP3
              support  without  incurring the patent holder’s fees.  Users who
              require SoX with MP3 support must currently  compile  and  build
              SoX with the MP3 libraries (LAME & MAD) from source code.

              See also Ogg Vorbis for a similar format.

       .mp4, .m4a (optional)
              MP4  compressed  audio.   MP3  (MPEG  4)  is  part  of  the MPEG
              standards for audio and video compression.   See  mp3  for  more

       .nist (also with -t sndfile)
              See .sph.

       .ogg, .vorbis (optional)
    ’s  Ogg  Vorbis  compressed  audio; an open, patent-free
              CODEC designed for music and streaming audio.   It  is  a  lossy
              compression  format  (similar  to  MP3, VQF & AAC) that achieves
              good compression rates with a minimum amount of quality loss.

              SoX can decode all types of Ogg Vorbis files, and can encode  at
              different compression levels/qualities given as a number from -1
              (highest compression/lowest quality) to 10 (lowest  compression,
              highest  quality).   By  default the encoding quality level is 3
              (which gives an encoded rate of approx. 112kbps), but  this  can
              be changed using the -C option (see above) with a number from -1
              to  10;  fractional  numbers  (e.g.   3.6)  are  also   allowed.
              Decoding  is  somewhat  CPU  intensive  and encoding is very CPU

              See also .mp3 for a similar format.

       oss (optional)
              Open Sound System /dev/dsp device driver; supports both  playing
              and  recording  audio.   OSS  support  is available in Unix-like
              operating systems, sometimes  together  with  alternative  sound
              systems (such as ALSA).  Examples:

                   sox infile -t oss
                   sox infile -t oss /dev/dsp
                   sox -2 -t oss /dev/dsp outfile

              See also play(1) and rec(1).

       .paf, .fap (optional)
              Ensoniq  PARIS file format (big and little-endian respectively).

       .pls   A playlist format; contains a list  of  audio  files.   SoX  can
              read,  but  not  write this file format.  See [2] for details of
              this format.

              Note: SoX support for SHOUTcast PLS relies  on  wget(1)  and  is
              only  partially  supported:  it’s necessary to specify the audio
              type manually, e.g.

                   play -t mp3 "http://a.server/pls?rn=265&file=filename.pls"

              and SoX does not know about alternative  servers  -  hit  Ctrl-C
              twice in quick succession to quit.

       .prc   Psion  Record.  Used  in  Psion  EPOC  PDAs  (Series 5, Revo and
              similar) for System alarms and recordings made by  the  built-in
              Record  application.  When writing, SoX defaults to A-law, which
              is recommended; if you must use ADPCM, then use the  -i  switch.
              The  sound  quality is poor because Psion Record seems to insist
              on frames of 800 samples or fewer, so that the ADPCM  CODEC  has
              to  be  reset  at  every  800  frames, which causes the sound to
              glitch every tenth of a second.

       .pvf (optional)
              Portable Voice Format.

       .sd2 (optional)
              Sound Designer 2 format.

       .sds (optional)
              MIDI Sample Dump Standard.

       .sf (also with -t sndfile)
              IRCAM   SDIF   (Institut   de    Recherche    et    Coordination
              Acoustique/Musique  Sound  Description Interchange Format). Used
              by academic music software such as the CSound package,  and  the
              MixView sound sample editor.

       .sph, .nist (also with -t sndfile)
              SPHERE  (SPeech  HEader  Resources)  is a file format defined by
              NIST (National Institute of Standards  and  Technology)  and  is
              used  with  speech  audio.   SoX  can read these files when they
              contain  μ-law  and  PCM  data.   It  will  ignore  any   header
              information  that  says  the  data  is  compressed using shorten
              compression and will treat the data  as  either  μ-law  or  PCM.
              This  will  allow SoX and the command line shorten program to be
              run together using pipes to encompasses the data and  then  pass
              the result to SoX for processing.

       .smp   Turtle Beach SampleVision files.  SMP files are for use with the
              PC-DOS package SampleVision by  Turtle  Beach  Softworks.   This
              package  is  for  communication  to  several MIDI samplers.  All
              sample rates are supported by the package, although not all  are
              supported by the samplers themselves.  Currently loop points are

       .snd   See .au, .sndr and .sndt.

       sndfile (optional)
              This is a pseudo-type that forces libsndfile  to  be  used.  For
              writing  files,  the  actual  file  type  is then taken from the
              output file name; for reading them, it is deduced from the file.

       sndio (optional)
              OpenBSD audio device driver; supports both playing and recording

                   sox infile -t sndio

              See also play(1) and rec(1).

       .sndr  Sounder files.  An MS-DOS/Windows format from  the  early  ’90s.
              Sounder files usually have the extension ‘.SND’.

       .sndt  SoundTool  files.  An MS-DOS/Windows format from the early ’90s.
              SoundTool files usually have the extension ‘.SND’.

       .sou   An alias for the .u8 raw format.

       .sox   SoX’s native uncompressed PCM format, intended for  storing  (or
              piping)  audio  at  intermediate processing points (i.e. between
              SoX invocations).  It has much in common with the  popular  WAV,
              AIFF,  and  AU  uncompressed  PCM formats, but has the following
              specific characteristics: the PCM samples are always  stored  as
              32  bit  signed integers, the samples are stored (by default) as
              ‘native endian’, and the  number  of  samples  in  the  file  is
              recorded as a 64-bit integer.  Comments are also supported.

              See ‘Special Filenames’ in sox(1) for examples of using the .sox
              format with ‘pipes’.

       sunau (optional)
              Sun  /dev/audio  device  driver;  supports  both   playing   and
              recording audio.  For example:

                   sox infile -t sunau /dev/audio


                   sox infile -t sunau -U -c 1 /dev/audio

              for older sun equipment.

              See also play(1) and rec(1).

       .txw   Yamaha  TX-16W  sampler.   A  file format from a Yamaha sampling
              keyboard which  wrote  IBM-PC  format  3.5"  floppies.   Handles
              reading  of files which do not have the sample rate field set to
              one of the expected by  looking  at  some  other  bytes  in  the
              attack/loop  length  fields,  and  defaulting  to  33 kHz if the
              sample rate is still unknown.

       .vms   See .dvms.

       .voc (also with -t sndfile)
              Sound Blaster VOC files.  VOC files are multi-part  and  contain
              silence parts, looping, and different sample rates for different
              chunks.  On input, the silence parts are filled out,  loops  are
              rejected,  and  sample  data with a new sample rate is rejected.
              Silence with a different sample rate is generated appropriately.
              On  output,  silence  is not detected, nor are impossible sample
              rates.  SoX supports reading (but not writing)  VOC  files  with
              multiple   blocks,   and  files  containing  μ-law,  A-law,  and
              2/3/4-bit ADPCM samples.

              See .ogg.

       .vox (also with -t sndfile)
              A headerless file of  Dialogic/OKI  ADPCM  audio  data  commonly
              comes  with  the  extension  .vox.   This  ADPCM data has 12-bit
              precision packed into only 4-bits.

              Note: some early Dialogic hardware does  not  always  reset  the
              ADPCM encoder at the start of each vox file.  This can result in
              clipping and/or DC offset problems when it comes to decoding the
              audio.   Whilst  little  can  be  done  about the clipping, a DC
              offset can be removed by passing the  decoded  audio  through  a
              high-pass filter, e.g.:

                   sox input.vox output.wav highpass 10

       .w64 (optional)
              Sonic Foundry’s 64-bit RIFF/WAV format.

       .wav (also with -t sndfile)
              Microsoft .WAV RIFF files.  This is the native audio file format
              of Windows, and widely used for uncompressed audio.

              Normally .wav files have all  formatting  information  in  their
              headers,  and so do not need any format options specified for an
              input file.  If any are, they will override the file header, and
              you will be warned to this effect.  You had better know what you
              are doing! Output format options will cause a format conversion,
              and the .wav will written appropriately.

              SoX  can read and write PCM, μ-law, A-law, MS ADPCM, and IMA (or
              DVI) ADPCM.  Big endian versions of RIFF files, called RIFX, are
              also  supported.   To  write a RIFX file, use the -B option with
              the output file options.

              A  non-standard,  but  widely  used,  variant  of  .wav.    Some
              applications  cannot  read  a  standard WAV file header for PCM-
              encoded data with sample-size greater than 16-bits or with  more
              than  two  channels, but can read a non-standard WAV header.  It
              is likely that such applications will eventually be  updated  to
              support  the  standard  header,  but  in the mean time, this SoX
              format can be used to create files with the non-standard  header
              that  should  work with these applications.  (Note that SoX will
              automatically detect and read WAV files  with  the  non-standard

              The  most common use of this file-type is likely to be along the
              following lines:

                   sox infile.any -t wavpcm -s outfile.wav

       .wv (optional)
              WavPack lossless audio compression.  Note that, when  converting
              .wav  to  this  format  and  back  again, the RIFF header is not
              necessarily preserved losslessly (though the audio is).

       .wve (also with -t sndfile)
              Psion 8-bit A-law.  Used  on  Psion  SIBO  PDAs  (Series  3  and
              similar).   This  format is deprecated in SoX, but will continue
              to be used in libsndfile.

       .xa    Maxis XA files.  These are 16-bit  ADPCM  audio  files  used  by
              Maxis  games.   Writing  .xa  files  is currently not supported,
              although adding write support should not be very difficult.

       .xi (optional)
              Fasttracker 2 Extended Instrument format.


       sox(1), soxi(1), libsox(3), octave(1), wget(1)

       The SoX web page at
       SoX scripting examples at

       [1]    Wikipedia, M3U,

       [2]    Wikipedia, PLS,


       Copyright 1998-2009 Chris Bagwell and SoX Contributors.
       Copyright 1991 Lance Norskog and Sundry Contributors.


       Chris  Bagwell  (   Other  authors  and
       contributors  are listed in the ChangeLog file that is distributed with
       the source code.