NAME

       collectiongain - large scale Replay Gain calculating tool

SYNOPSIS

       collectiongain [options] music_dir
       collectiongain --help
       collectiongain --version

DESCRIPTION

       collectiongain  is  a  script  calculating  the Replay Gain values of a large set of music
       files inside music_dir. Each audio file will be rectified against the other files  of  the
       same album, which are identified using the file tags.

OPTIONS

       --version
              Display the version of the software.

       -h, --help
              Display a short summary of the available options.

       -f, --force
              Recalculate Replay Gain even if the file already contains gain information.

       -d, --dry-run
              Don't actually modify any files.

       -r REF, --reference-loudness=REF
              Set the reference loudness to REF dB (default: 89 dB)

       --mp3-format=MP3_FORMAT
              Choose  the  Replay  Gain  data format for MP3 files. The default setting should be
              compatible with most  decent  software  music  players,  so  it  is  generally  not
              necessary to mess with this setting. See below for more information.

       --ignore-cache
              Don't  trust  implicit  assumptions  about what was already done, instead check all
              files for Replay Gain data explicitly.

       -j JOBS, --jobs=JOBS
              Run JOBS jobs simultaneously. Must be >= 1. By default, this is set to  the  number
              of CPU cores in the system to provide best performance.

MP3 FORMATS

       Proper Replay Gain support for MP3 files is a bit of a mess: on the one hand, there is the
       mp3gain application [1] which was relatively widely used (I don't know if it still is)  --
       it directly modifies the audio data which has the advantage that it works with pretty much
       any player, but it also means you have to decide ahead of time whether you want track gain
       or  album gain. Besides, it's just not very elegant. On the other hand, there are at least
       two commonly used ways to store proper Replay Gain information in ID3v2 tags [2].

       Now, in general you don't have to worry about this when using this  package:  by  default,
       replaygain  and collectiongain will read and write Replay Gain information in the two most
       commonly used formats. However, if for whatever reason you need more control over the  MP3
       Replay  Gain information, you can use the --mp3-format option (supported by both programs)
       to change the behaviour. Possible choices with this switch are:

          • replaygain.org (alias: fb2k) Replay Gain information is stored in ID3v2 TXXX  frames.
            This  format is specified on the replaygain.org website as the recommended format for
            MP3 files. Notably, this format is also used  by  the  foobar2000  music  player  for
            Windows [3].

          • legacy  (alias:  ql)  Replay  Gain information is stored in ID3v2.4 RVA2 frames. This
            format is described as "legacy" by replaygain.org; however, it is still  the  primary
            format for at least the Quod Libet music player [4] and possibly others. It should be
            noted that this format does not support volume adjustments of more than 64 dB: if the
            calculated  gain  value is smaller than -64 dB or greater than or equal to +64 dB, it
            is clamped to these limit values.

          • default  This  is  the  default  implementation   used   by   both   replaygain   and
            collectiongain. When writing Replay Gain data, both the replaygain.org as well as the
            legacy format are written. As for reading, if a file contains data in  both  formats,
            both  data  sets  are  read  and  then  compared.  If they match up, that Replay Gain
            information is returned for the file.  However, if they don't match, no  Replay  Gain
            data  is  returned to signal that this file does not contain valid (read: consistent)
            Replay Gain information.

       [1] http://mp3gain.sourceforce.net

       [2] http://wiki.hydrogenaudio.org/index.php?title=ReplayGain_specification#ID3v2

       [3] http://foobar2000.org

       [4] http://code.google.com/p/quodlibet

SEE ALSO

       replaygain(1)