loudgain

**loudgain**
{{{logo}}}
Loudgain running in a Linux terminal window.
Developer(s)	Matthias C. Hormann, Alessandro Ghedini
Release information
Initial release	22 June 2014
Stable release	0.6.8 (September 6, 2019)
Preview release	{{{preview_release}}}
Compatibility
Operating system	Linux, MacOS
Additional information
Use	Tagging
License	BSD license
Website	{{{website}}}

loudgain is an open-source ReplayGain 2 tagging tool for Linux, MacOS (via Homebrew) and Windows 10 (via the Linux bash). It analyzes many types of audio files, based on the EBU R128/ITU BS.1170 standard (at -18 LUFS), and uses the well-known MP3Gain commandline syntax. Loudgain never modifies the audio data, but instead only writes the appropriate ReplayGain tags.

For mass-tagging (assuming one album per folder), loudgain comes with a bash script called rgbpm that can be modified to the user’s needs.

Technical details

Loudgain computes the ReplayGain (volume adjustment), true peak value and loudness range, using the EBU R128 algorithm for each track and (optionally) a whole album. The optional clipping prevention feature can further reduce the computed gain to a level where no clipping should occur (default -1 dBTP). Computed values are then written to the audio files as tags in a suitable tag format.

For extra versatility, loudgain also supports writing the loudness range and loudness reference values, forcing upper- or lowercase ReplayGain tags, and stripping "foreign" tags from some file types.

Supported file formats

Supported audio file formats as of version 0.6.8:
- FLAC: Values written to Vorbis comment.
- MP2, MP3: Values written to ID3v2 tags (ID3v2.3/ID3v2.4 selectable).
- (Ogg) Vorbis: Values written to Vorbis comment.
- (Ogg) FLAC: Values written to Vorbis comment.
- (Ogg) Speex: Values written to Vorbis comment.
- Opus: Values written to Vorbis comment, based on -23 LUFS Opus standard. Only R128_TRACK_GAIN and R128_ALBUM_GAIN are written, but the calculated true peak value can still be used to reduce the gain values (Clipping prevention).
- MP4, M4A: Uses its own iTunes-compatible tagging system (though iTunes does not support ReplayGain). ReplayGain values are stored under ----:com.apple.iTunes:…. This is for AAC and ALAC in MPEG-4 containers.
- ASF, WMA: Values written to WMA tags, no prefix.
- WAV: Values written to the ID3 chunk, in ID3v2 (ID3v2.3/ID3v2.4 selectable) format. Using the bext chunk (for BWF v2) isn’t (yet) supported, but won’t be destroyed on writing.
- AIFF: Values written to the ID3 chunk, in ID3v2 format.
- WavPack: Values written to APEv2 tags.
- Monkey's Audio (APE): Values written to APEv2 tags.

Development

loudgain v0.1 was originally developed by Alessandro Ghedini in 2014.

Matthias C. Hormann forked this version in 2019 and took over the development of loudgain after version 0.1, starting with version 0.2.1. The latest version is 0.6.8.

Command line help

Usage: loudgain [OPTIONS] FILES...

loudgain 0.6.8 supports writing tags to the following file types:
  FLAC (.flac), Ogg (.ogg, .oga, .spx, .opus), MP2 (.mp2), MP3 (.mp3),
  MP4 (.mp4, .m4a), ASF/WMA (.asf, .wma), WavPack (.wv), APE (.ape).
  Experimental: WAV (.wav), AIFF (.aiff, .aif).

Options:
  -h,   --help            Show this help.
  -v,   --version         Show version number.

  -r,   --track           Calculate track gain only (default).
  -a,   --album           Calculate album gain (and track gain).

  -c,   --clip            Ignore clipping warning.
  -k,   --noclip          Lower track/album gain to avoid clipping (<= -1 dBTP).
  -K n, --maxtpl=n        Avoid clipping; max. true peak level = n dBTP.
  -d n, --pregain=n       Apply n dB/LU pre-gain value (-5 for -23 LUFS target).

  -s d, --tagmode=d       Delete ReplayGain tags from files.
  -s i, --tagmode=i       Write ReplayGain 2.0 tags to files.
  -s e, --tagmode=e       like '-s i', plus extra tags (reference, ranges).
  -s l, --tagmode=l       like '-s e', but LU units instead of dB.
  -s s, --tagmode=s       Don't write ReplayGain tags (default).

  -L,   --lowercase       Force lowercase tags (MP2/MP3/MP4/WMA/WAV/AIFF).
                          This is non-standard but sometimes needed.
  -S,   --striptags       Strip tag types other than ID3v2 from MP2/MP3.
                          Strip tag types other than APEv2 from WavPack/APE.
  -I 3, --id3v2version=3  Write ID3v2.3 tags to MP2/MP3/WAV files.
  -I 4, --id3v2version=4  Write ID3v2.4 tags to MP2/MP3/WAV files (default).

  -o,   --output          Database-friendly tab-delimited list output.
  -O,   --output-new      New format tab-delimited list output.
  -q,   --quiet           Don't print scanning status messages.

Please report any issues to https://github.com/Moonbase59/loudgain/issues.

Closer analysis of files

Using the -O (uppercase letter O) switch, loudgain can produce a detailed tab-separated list, ideal for redirection into a .csv spreadsheet file and later analysis.

Simply use a command like the following and then import the .csv file into your spreadsheet application, specifying "tab-delimited":

loudgain -O [OPTIONS] FILES... > album.csv

Known problems

Loudgain relies on standard libraries like TagLib. Linux distros (except rolling releases) sometimes deliver outdated libraries, so be sure you use the latest version of TagLib. Version 1.11.1 had a nasty bug for a while that could corrupt Ogg Vorbis files. This has been fixed in the meantime but the TagLib version not updated. Loudgain comes with a (slower) static version called loudgain.static in the repo’s /bin folder that doesn’t expose the bug and can also be used on older Linux versions (like Ubuntu 14.04, Linux Mint 17).

External links