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NORMALIZE(1)							  NORMALIZE(1)

NAME
       normalize - adjusts volume levels of audio files.

SYNOPSIS
       normalize [ options ] [ -- ] file ...

DESCRIPTION
       normalize is used to adjust the volume of wav audio files to a standard
       volume level.  This is useful for things	like creating mp3 mixes, where
       different  recording levels on different	albums can cause the volume to
       vary greatly from song to song.

       normalize operates in two phases.  In the first phase, it analyzes  the
       specified  files	 as  wav  audio	files, and computes the	volume of each
       file.  In the second phase, it applies a	volume adjustment to each file
       to set each file's volume to a standard level.

OPTIONS
       -a, --amplitude=AMPLITUDE
	      Adjust the RMS volume to the target amplitude AMPLITUDE; must be
	      between 0.0 and 1.0.  If a number	suffixed by "dB" or "dBFS"  is
	      specified,  the amplitude	is assumed to be in decibels from full
	      scale.  The default is -12dBFS.

       -b, --batch
	      Enable batch mode: see BATCH MODE, below.

       -c, --compression
	      Deprecated.  In previous versions, this enabled the limiter, but
	      now the limiter is enabled by default.

       --clipping
	      Disable  the  limiter,  and  just	 clip any samples that are too
	      large.  Same effect as -l	0dBFS.

       --fractions
	      Display all values as decimal fractions instead of in  decibels.
	      By default, volume adjustments are shown in decibels, and	volume
	      levels in	dBFS, where 0 dBFS is the level	of a  square  wave  of
	      maximum amplitude.

       -g, --gain=GAIN
	      Skip  the	volume computation phase: don't	compute	the volume ad-
	      justment from the	current	volumes	of the files.	Instead,  just
	      apply  the given gain as a volume	adjustment to all files.  As a
	      plain number this	is just	a multiplier applied to	 all  samples,
	      If  a  number suffixed by	"dB" is	specified, all volumes are ad-
	      justed by	that many decibels.

       --id3-compat
	      Use this option when adjusting MPEG  audio  files	 if  your  MP3
	      player  does not recognize ID3v2.4 tags.	See MPEG AUDIO ADJUST-
	      MENT, below, for details.

       --id3-unsync
	      Use this option when adjusting MPEG  audio  files	 if  your  MP3
	      player  does  not	 recognize  ID3v2 tags and has trouble playing
	      some ID3v2 tagged	MP3 files.  See	MPEG AUDIO ADJUSTMENT,	below,
	      for details.

       -l, --limiter=LEVEL
	      This controls the	behavior of the	limiter.  By default, all sam-
	      ples above -6dBFS	(0.5) are limited, but this  option  sets  the
	      limiting	level  to LEVEL. Setting LEVEL to 1 (or	0dBFS) does no
	      limiting (clipping is done instead); setting  LEVEL  to  0  does
	      limiting	on  all	samples.  The default value is recommended un-
	      less you know what you're	doing.

       -m, --mix
	      Enable mix mode: see MIX MODE, below.  Batch mode	and  mix  mode
	      are mutually exclusive.

       -n, --no-adjust
	      Compute and output the volume adjustment that would set the vol-
	      ume to the target, but don't apply it to any of the files	 (i.e.
	      skip the second phase).  If you use this option, your files will
	      not be altered in	any way.

       --no-progress
	      Don't print any progress information.  All  other	 messages  are
	      printed as normal	according to the verbosity level.

       --peak Adjust  using peak levels	instead	of RMS levels.	Each file will
	      be adjusted so that its maximum sample is	at full	 scale.	  This
	      just  gives a file the maximum volume possible without clipping;
	      no normalization is done.

       -q, --quiet
	      Don't output progress  information.   Only  error	 messages  are
	      printed.

       -t, --average-threshold=THRESHOLD
	      When  averaging  volume levels for batch mode or mix mode, throw
	      out any volumes that are more than THRESHOLD decibels  from  the
	      average.	 A  high  value	here (say, 50) will make sure that the
	      volumes of all files are considered in the average.

       -T, --adjust-threshold=THRESHOLD
	      If an adjustment to be made to a file is smaller than  THRESHOLD
	      decibels,	 consider the file already normalized and don't	do the
	      adjustment.  This	is 0.125 by default, or	0 if the -g option  is
	      given.

       -v, --verbose
	      Increase	verbosity.   This option can be	repeated for more mes-
	      sages.

       -w, --output-bitwidth
	      Force output files to have samples that are W bits  wide.	  This
	      option is	ignored	when adjusting MP3 files.

       -h, --help
	      Display usage information	and exit.

       -V, --version
	      Print version information	and exit.

       --     Terminate	option list.

MIX MODE
       This  mode  is made especially for making mixed CD's and	the like.  You
       want every song on the mix to be	the same volume, but it	doesn't	matter
       if  they	 are  the  same	volume as the songs on some other mix you made
       last week.  In mix mode,	average	level of all the  files	 is  computed,
       and each	file is	separately normalized to this average volume.

BATCH MODE
       When  operating	on a group of unrelated	files, you usually want	all of
       them at the same	level, and this	is the default behavior.   However,  a
       group  of  music	files all from the same	album is generally meant to be
       listened	to at the relative volumes they	were recorded  at.   In	 batch
       mode, all the specified files are considered to be part of a single al-
       bum and their relative volumes are preserved.  This is done by  averag-
       ing  the	 volumes  of all the files, computing a	single adjustment from
       that, and applying the same adjustment to all the files.	 Some analysis
       is  also	 done so that files with volumes that appear to	be statistical
       aberrations are not considered in the average.  This is useful  if  you
       have  albums  (like  many of the	author's) in which there is one	"quiet
       song" that throws off the average.

MPEG AUDIO ADJUSTMENT
       MP3 files are "adjusted"	by setting a relative volume adjustment	 frame
       in their	ID3 tags.  There is a frame for	this, called "RVA2", that does
       exactly what we want, and is a native frame in ID3v2.4.	Unfortunately,
       many  MP3 players do not	support	v2.4 tags, and the RVA2	tag is not na-
       tive in previous	ID3 versions.  In fact,	adding an RVA2 frame to	a v2.3
       tag confuses some MP3 players.  Therefore, we are left with two choices
       when trying to add volume adjustment information	to an ID3 tag:

       1. Go ahead and upgrade the tag to version  2.4,	 and  use  RVA2	 tags.
	  This	is the default behavior, in the	hope that eventually MP3 play-
	  ers will support v2.4	tags and this won't be a problem anymore.

       2. Upgrade the tag to only version 2.3.	Instead	of RVA2, use an	"XRVA"
	  tag with the same format as an RVA2 tag.  This isn't a native	frame,
	  but since it starts with an "X", it's	 considered  experimental  and
	  therefore legal, according to	the ID3	spec.  The --id3-compat	option
	  turns	on this	behavior.  The disadvantage of	the  first  method  is
	  that	your MP3 player	may no longer read the ID3 tags	on your	files.
	  Bug the author of your favorite MP3 player to	support	ID3v2.4	tags!

       The disadvantage	of the second method is	that the XRVA  frame  is  only
       recognized  by the xmms-rva plugin that is packaged with	normalize.  On
       the other hand, I don't know of any MP3 players that recognize the RVA2
       frame, either, so it may	not make any difference.

       The  other  option related to ID3 tags, --id3-unsync, is	only necessary
       for compatibility with old MP3 players that don't recognize ID3v2  tags
       at all.	If your	MP3 player complains of	garbage	at the start of	tagged
       files, or is unable to play the files at	 all,  turn  this  option  on.
       This option should never	hurt, but if your MP3 player knows about ID3v2
       tags, you don't need it.

CAVEATS
       Note that your version of normalize must	be compiled with  MAD  library
       support to analyze MP3 file volume levels.

AUTHOR
       Chris Vaill <chrisvaill@gmail.com>

SEE ALSO
       sox(1)

			       14 September 2005		  NORMALIZE(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | MIX MODE | BATCH MODE | MPEG AUDIO ADJUSTMENT | CAVEATS | AUTHOR | SEE ALSO

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