ReplayGain - Revision history

Case: /* foobar2000 ReplayGain scanner */

2026-01-23T13:31:32Z

foobar2000 ReplayGain scanner

Case: /* Target loudness */

2026-01-23T11:02:51Z

Target loudness

← Older revision		Revision as of 11:02, 23 January 2026
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	==Target loudness==		==Target loudness==
	The target loudness of ~~all~~ ReplayGain ~~utilities~~ is ~~89 dB SPL when replayed in an SMPTE RP 200 calibrated system (an early departure from the proposal, endorsed by its author<ref>~~[~~http~~://~~www~~.hydrogenaudio.org~~/forums~~/index.php?s=~~&showtopic=83397&view=findpost&p=721854 Does Replay gain work differtly in Media monkey]</ref>) — the ReplayGain proposal and SMPTE recommendation are 6~~ dB ~~lower.<ref>[http://www.mars.org/mailman/public/mad-dev/2004-February/000993.html ReplayGain discussion at mad-dev~~]</~~ref> The target loudness may be more commonly known and understood as~~ '''-18''' '''[https://en.wikipedia.org/wiki/LUFS LUFS]''' (''Loudness Units relative to Full Scale'').		The target loudness of ReplayGain is [https://wiki.hydrogenaudio.org/index.php?title=Original_ReplayGain_specification#Reference_level '''89''' '''dB SPL'''] / '''-18''' '''[https://en.wikipedia.org/wiki/LUFS LUFS]''' (''Loudness Units relative to Full Scale'').

	Some utilities have realized the inadequacies of the classic ReplayGain loudness calculation, switching to a more modern algorithm ([https://www.itu.int/rec/R-REC-BS.1770-5-202311-I/en ITU-R BS.1770]). However, the way it was integrated was extremely ''ad hoc'', at least until a draft of a [[ReplayGain 2.0 specification\|revised specification]] started being written.		Some utilities have realized the inadequacies of the classic ReplayGain loudness calculation, switching to a more modern algorithm ([https://www.itu.int/rec/R-REC-BS.1770-5-202311-I/en ITU-R BS.1770]). However, the way it was integrated was extremely ''ad hoc'', at least until a draft of a [[ReplayGain 2.0 specification\|revised specification]] started being written.

Case: /* foobar2000 ReplayGain scanner */

2026-01-23T10:25:15Z

foobar2000 ReplayGain scanner

← Older revision		Revision as of 10:25, 23 January 2026
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	** [[WavPack]]: Values written to [[APEv2]] tags.		** [[WavPack]]: Values written to [[APEv2]] tags.
	** [[AAC]]: Values written to [[APEv2]] tags		** [[AAC]]: Values written to [[APEv2]] tags
	** [[MP4]]: Uses its own iTunes-compatible tagging system (though iTunes does not support ReplayGain). ~~Can write chosen Gain value to Apple's SoundCheck~~		** [[MP4]]: Uses its own iTunes-compatible tagging system (though iTunes does not support ReplayGain).
	** [[Free Lossless Audio Codec\|FLAC]]: Values written to [[Vorbis comment]].		** [[Free Lossless Audio Codec\|FLAC]]: Values written to [[Vorbis comment]].
	** [[APE]]: Values written to [[APEv2]] tags.		** [[APE]]: Values written to [[APEv2]] tags.

Case: /* foobar2000 ReplayGain scanner */

2026-01-23T10:24:41Z

foobar2000 ReplayGain scanner

← Older revision		Revision as of 10:24, 23 January 2026
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	** [[Opus]]: Values written to [[Vorbis comment]] and/or file header.		** [[Opus]]: Values written to [[Vorbis comment]] and/or file header.
	** [[WavPack]]: Values written to [[APEv2]] tags.		** [[WavPack]]: Values written to [[APEv2]] tags.
	** [[AAC]]: Values written to [[APEv2]] tags~~. As with MP3, it is also an option to apply gain via a separate function.~~		** [[AAC]]: Values written to [[APEv2]] tags
	** [[MP4]]: Uses its own iTunes-compatible tagging system (though iTunes does not support ReplayGain). Can write chosen Gain value to Apple's SoundCheck		** [[MP4]]: Uses its own iTunes-compatible tagging system (though iTunes does not support ReplayGain). Can write chosen Gain value to Apple's SoundCheck
	** [[Free Lossless Audio Codec\|FLAC]]: Values written to [[Vorbis comment]].		** [[Free Lossless Audio Codec\|FLAC]]: Values written to [[Vorbis comment]].
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	** [[TTA]]: Values written to [[APEv2]] or [[ID3v2]] tags.		** [[TTA]]: Values written to [[APEv2]] or [[ID3v2]] tags.
	** [[WMA]]: Values written to WMA tags.		** [[WMA]]: Values written to WMA tags.
			** [[WAV]]: Values written to ID3 chunk.
			** [[AIFF]]: Values written to ID3 chunk.
	** Modules ([[MOD]] etc.): Optionally saved into [[APEv2]] tags.		** Modules ([[MOD]] etc.): Optionally saved into [[APEv2]] tags.
	** Any non-taggable format or format supported by FFmpeg can store RG values in a database or external tag with a component.		** Any non-taggable format or format supported by FFmpeg can store RG values in a database or external tag with a component.

Skamp at 09:12, 23 January 2026

2026-01-23T09:12:44Z

← Older revision		Revision as of 09:12, 23 January 2026
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	Implementations deal with the risk of clipping in different ways. Some have a "pre-amp" feature which reduces (or boosts) the original audio's level by a certain amount before doing whatever is needed for ReplayGain. Some have a "prevent clipping" feature to reduce the amount of ReplayGain adjustment to whatever amount would keep clipping from occurring, based on peak info stored in the file's metadata (thus reducing the effectiveness of ReplayGain). Some recommend using a compressor/limiter DSP to prevent or reduce clipping, regardless of whether it was caused by ReplayGain.		Implementations deal with the risk of clipping in different ways. Some have a "pre-amp" feature which reduces (or boosts) the original audio's level by a certain amount before doing whatever is needed for ReplayGain. Some have a "prevent clipping" feature to reduce the amount of ReplayGain adjustment to whatever amount would keep clipping from occurring, based on peak info stored in the file's metadata (thus reducing the effectiveness of ReplayGain). Some recommend using a compressor/limiter DSP to prevent or reduce clipping, regardless of whether it was caused by ReplayGain.

	An alternative that may reduce the risk of clipping is the [https://tech.ebu.ch/docs/r/r128.pdf EBU R 128] recommendation of a ~~'''~~-23~~'''~~ ~~'''~~LUFS~~'''~~ target, but that's a different standard, and some may find the additional reduction in volume excessive, particularly if it leads to maxing out volume on user hardware. [[Opus]] in particular has adopted that standard, using a global gain as well as <code>R128_TRACK_GAIN</code> / <code>R128_ALBUM_GAIN</code> tags. With ReplayGain, a simple (though somewhat radical) solution is to lower the preamp value by 5 dB (or whatever one feels comfortable with) in the playback software.		An alternative that may reduce the risk of clipping is the [https://tech.ebu.ch/docs/r/r128.pdf EBU R 128] recommendation of a -23 LUFS target, but that's a different standard, and some may find the additional reduction in volume excessive, particularly if it leads to maxing out volume on user hardware. [[Opus]] in particular has adopted that standard, using a global gain as well as <code>R128_TRACK_GAIN</code> / <code>R128_ALBUM_GAIN</code> tags. With ReplayGain, a simple (though somewhat radical) solution is to lower the preamp value by 5 dB (or whatever one feels comfortable with) in the playback software. The RG target will always be -18 LUFS, regardless of a user's volume or preamp settings.

	== Implementations ==		== Implementations ==

Skamp: Clarification about possible clipping with the ReplayGain target level.

2026-01-23T09:09:58Z

Clarification about possible clipping with the ReplayGain target level.

← Older revision		Revision as of 09:09, 23 January 2026
Line 6:		Line 6:

	==Target loudness==		==Target loudness==
	The target loudness of ~~almost~~ all ReplayGain utilities is 89 dB SPL when replayed in an SMPTE RP 200 calibrated system (an early departure from the proposal, endorsed by its author<ref>[http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=83397&view=findpost&p=721854 Does Replay gain work differtly in Media monkey]</ref>) — the ReplayGain proposal and SMPTE recommendation are 6 dB lower.<ref>[http://www.mars.org/mailman/public/mad-dev/2004-February/000993.html ReplayGain discussion at mad-dev]</ref> The target loudness may be more commonly known and understood as '''-18''' '''[https://en.wikipedia.org/wiki/LUFS LUFS]''' (''Loudness Units relative to Full Scale'').		The target loudness of all ReplayGain utilities is 89 dB SPL when replayed in an SMPTE RP 200 calibrated system (an early departure from the proposal, endorsed by its author<ref>[http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=83397&view=findpost&p=721854 Does Replay gain work differtly in Media monkey]</ref>) — the ReplayGain proposal and SMPTE recommendation are 6 dB lower.<ref>[http://www.mars.org/mailman/public/mad-dev/2004-February/000993.html ReplayGain discussion at mad-dev]</ref> The target loudness may be more commonly known and understood as '''-18''' '''[https://en.wikipedia.org/wiki/LUFS LUFS]''' (''Loudness Units relative to Full Scale'').

	Some utilities have realized the inadequacies of the classic ReplayGain loudness calculation, switching to a more modern algorithm ([https://www.itu.int/rec/R-REC-BS.1770-5-202311-I/en ITU-R BS.1770]). However, the way it was integrated was extremely ''ad hoc'', at least until a draft of a [[ReplayGain 2.0 specification\|revised specification]] started being written.		Some utilities have realized the inadequacies of the classic ReplayGain loudness calculation, switching to a more modern algorithm ([https://www.itu.int/rec/R-REC-BS.1770-5-202311-I/en ITU-R BS.1770]). However, the way it was integrated was extremely ''ad hoc'', at least until a draft of a [[ReplayGain 2.0 specification\|revised specification]] started being written.
Line 15:		Line 15:
	Implementations deal with the risk of clipping in different ways. Some have a "pre-amp" feature which reduces (or boosts) the original audio's level by a certain amount before doing whatever is needed for ReplayGain. Some have a "prevent clipping" feature to reduce the amount of ReplayGain adjustment to whatever amount would keep clipping from occurring, based on peak info stored in the file's metadata (thus reducing the effectiveness of ReplayGain). Some recommend using a compressor/limiter DSP to prevent or reduce clipping, regardless of whether it was caused by ReplayGain.		Implementations deal with the risk of clipping in different ways. Some have a "pre-amp" feature which reduces (or boosts) the original audio's level by a certain amount before doing whatever is needed for ReplayGain. Some have a "prevent clipping" feature to reduce the amount of ReplayGain adjustment to whatever amount would keep clipping from occurring, based on peak info stored in the file's metadata (thus reducing the effectiveness of ReplayGain). Some recommend using a compressor/limiter DSP to prevent or reduce clipping, regardless of whether it was caused by ReplayGain.

	An alternative that may reduce the risk of clipping is the [https://tech.ebu.ch/docs/r/r128.pdf EBU R 128] recommendation of a '''-23''' '''LUFS''' target, ~~although~~ some may find the additional reduction in volume excessive, particularly if it leads to maxing out volume on user hardware. [[Opus]] in particular has adopted that ~~recommendation~~.		An alternative that may reduce the risk of clipping is the [https://tech.ebu.ch/docs/r/r128.pdf EBU R 128] recommendation of a '''-23''' '''LUFS''' target, but that's a different standard, and some may find the additional reduction in volume excessive, particularly if it leads to maxing out volume on user hardware. [[Opus]] in particular has adopted that standard, using a global gain as well as <code>R128_TRACK_GAIN</code> / <code>R128_ALBUM_GAIN</code> tags. With ReplayGain, a simple (though somewhat radical) solution is to lower the preamp value by 5 dB (or whatever one feels comfortable with) in the playback software.

	== Implementations ==		== Implementations ==

Case: /* foobar2000 ReplayGain scanner */

2026-01-23T08:18:48Z

foobar2000 ReplayGain scanner

← Older revision		Revision as of 08:18, 23 January 2026
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	** Any non-taggable format or format supported by FFmpeg can store RG values in a database or external tag with a component.		** Any non-taggable format or format supported by FFmpeg can store RG values in a database or external tag with a component.
	** A separate function can be invoked to apply the tagged Track or Album Gain to the global gain fields in MP3, MP4 (AAC), or Opus files, and rewrite any existing tags to account for the peak change and compensate for the difference from 89 dB. The 89 dB reference level for tags isn't configurable, but the reference level applied to the global gain fields is.		** A separate function can be invoked to apply the tagged Track or Album Gain to the global gain fields in MP3, MP4 (AAC), or Opus files, and rewrite any existing tags to account for the peak change and compensate for the difference from 89 dB. The 89 dB reference level for tags isn't configurable, but the reference level applied to the global gain fields is.
			** Can automatically copy Track or Album gain values to Apple's SoundCheck tag in MP4 files or any format that supports ID3v2 to effectively add ReplayGain support to Apple's players.
	* https://foobar2000.org/		* https://foobar2000.org/

Case: /* foobar2000 ReplayGain scanner */

2026-01-23T08:14:08Z

foobar2000 ReplayGain scanner

← Older revision		Revision as of 08:14, 23 January 2026
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	* Since v1.1.6, defaults to ITU-R BS.1770 analysis (although it labels it EBU R128), but can be configured to use the "Classic ReplayGain" algorithm instead. The ITU-R BS.1770 implementation uses a reference level of -18 LUFS instead of -23, in order to retain compatibility with the ReplayGain standard.		* Since v1.1.6, defaults to ITU-R BS.1770 analysis (although it labels it EBU R128), but can be configured to use the "Classic ReplayGain" algorithm instead. The ITU-R BS.1770 implementation uses a reference level of -18 LUFS instead of -23, in order to retain compatibility with the ReplayGain standard.
	* Format:		* Format:
	** [[MP3]]: Values written to [[ID3v2]] (default) or [[APEv2]] tags. A separate function can be invoked to apply the tagged Track or Album Gain to the MP3 global gain fields (as MP3Gain does), and rewrite any existing tags to account for the peak change and compensate for the difference from 89 dB. The 89 dB reference level for tags isn't configurable, but the reference level applied to the global gain fields is (it's under Preferences > Advanced > Tools > ReplayGain Scanner > Target MP3 alteration volume level).		** [[MP3]]: Values written to [[ID3v2]] (default) or [[APEv2]] tags.
	** [[Musepack]]: Values written to header.		** [[Musepack]]: Values written to header.
	** (Ogg) [[Vorbis]]: Values written to [[Vorbis comment]].		** (Ogg) [[Vorbis]]: Values written to [[Vorbis comment]].
			** [[Opus]]: Values written to [[Vorbis comment]] and/or file header.
	** [[WavPack]]: Values written to [[APEv2]] tags.		** [[WavPack]]: Values written to [[APEv2]] tags.
	** [[AAC]]: Values written to [[APEv2]] tags. As with MP3, it is also an option to apply gain via a separate function.		** [[AAC]]: Values written to [[APEv2]] tags. As with MP3, it is also an option to apply gain via a separate function.
	** [[MP4]]: Uses its own iTunes-compatible tagging system (though iTunes does not support ReplayGain).		** [[MP4]]: Uses its own iTunes-compatible tagging system (though iTunes does not support ReplayGain). Can write chosen Gain value to Apple's SoundCheck
	** [[Free Lossless Audio Codec\|FLAC]]: Values written to [[Vorbis comment]].		** [[Free Lossless Audio Codec\|FLAC]]: Values written to [[Vorbis comment]].
	** [[APE]]: Values written to [[APEv2]] tags.		** [[APE]]: Values written to [[APEv2]] tags.
			** [[TAK]]: Values written to [[APEv2]] tags.
			** [[TTA]]: Values written to [[APEv2]] or [[ID3v2]] tags.
			** [[WMA]]: Values written to WMA tags.
	** Modules ([[MOD]] etc.): Optionally saved into [[APEv2]] tags.		** Modules ([[MOD]] etc.): Optionally saved into [[APEv2]] tags.
			** Any non-taggable format or format supported by FFmpeg can store RG values in a database or external tag with a component.
			** A separate function can be invoked to apply the tagged Track or Album Gain to the global gain fields in MP3, MP4 (AAC), or Opus files, and rewrite any existing tags to account for the peak change and compensate for the difference from 89 dB. The 89 dB reference level for tags isn't configurable, but the reference level applied to the global gain fields is.
	* https://foobar2000.org/		* https://foobar2000.org/

Case: /* MusicPlayer */

2026-01-23T07:48:40Z

MusicPlayer

← Older revision		Revision as of 07:48, 23 January 2026
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	=== MusicPlayer ===		=== MusicPlayer ===
	* Custom implementation, ~~not derived from the original MP3Gain one (but~~ inspired ~~from). As far as I know, all other implementations are directly derived from the~~ MP3Gain ~~(gain_analysis.c, which is GPL) source~~.		* Custom implementation, inspired by MP3Gain.
	* Format: any that FFmpeg supports		* Format: any that FFmpeg supports
	* Method: Audio		* Method: Audio

Skamp: More clarification about mentions of RG1 and RG2, online and elsewhere.

2026-01-22T20:24:53Z

More clarification about mentions of RG1 and RG2, online and elsewhere.

← Older revision		Revision as of 20:24, 22 January 2026
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	=== Old versus new algorithms ===		=== Old versus new algorithms ===
	Since the ReplayGain standard does not define tags to specify which algorithm was used (classic or ITU-R BS.1770) or what target was set (RG's -18 LUFS, EBU R 128's -23 LUFS, or any other target set by the user or some piece of software), there may be confusion as to how the results were produced. Typically, utilities that ship with reference encoders (FLAC / metaflac, Vorbis / vorbisgain, WavPack / wvgain, Musepack / mpcgain…) use the original RG algorithm, which can produce values that differ from newer tools by several decibels in certain cases. Generally speaking, it is recommended to run other utilities or players that implement the ITU-R BS.1770 algorithm, although it may not be obvious which algorithm they use at first glance. Their documentation may provide that information.		Since the ReplayGain standard does not define tags to specify which algorithm was used (classic or ITU-R BS.1770) or what target was set (RG's -18 LUFS, EBU R 128's -23 LUFS, or any other target set by the user or some piece of software), there may be confusion as to how the results were produced. Typically, utilities that ship with reference encoders (FLAC / metaflac, Vorbis / vorbisgain, WavPack / wvgain, Musepack / mpcgain…) use the original RG algorithm, which can produce values that differ from newer tools by several decibels in certain cases. Generally speaking, it is recommended to run other utilities or players that implement the ITU-R BS.1770 algorithm, although it may not be obvious which algorithm they use at first glance. Their documentation may provide that information.

			==== RG1, RG2 ====
			Although there are many references online, and within ReplayGain scanners, about version 1 vs. version 2 of the ReplayGain standard, at the time of writing this, there is (admittedly) only one ReplayGain standard. The core principle, as well as the 4 tags from the original specification, have not changed. More tags have been proposed but they are still subject to debate. As a rule of thumb, tools that advertise "ReplayGain 2" compliance employ the newer, more accurate ITU-R BS.1770 algorithm. [[foobar2000]] labels it "EBU R128" but it essentially means the same thing. Should a better algorithm be developed in the future, it will still work towards fulfilling ReplayGain's original goals, and probably write the same tags.

	=== MP3Gain ===		=== MP3Gain ===

← Older revision		Revision as of 13:31, 23 January 2026
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	** [[WavPack]]: Values written to [[APEv2]] tags.		** [[WavPack]]: Values written to [[APEv2]] tags.
	** [[AAC]]: Values written to [[APEv2]] tags		** [[AAC]]: Values written to [[APEv2]] tags
	** [[MP4]]: Uses its own iTunes-compatible tagging system (though iTunes does not support ReplayGain).		** [[MP4]] (AAC, ALAC, MP3): Uses its own iTunes-compatible tagging system (though iTunes does not support ReplayGain).
	** [[Free Lossless Audio Codec\|FLAC]]: Values written to [[Vorbis comment]].		** [[Free Lossless Audio Codec\|FLAC]]: Values written to [[Vorbis comment]].
	** [[APE]]: Values written to [[APEv2]] tags.		** [[APE]]: Values written to [[APEv2]] tags.
Line 118:		Line 118:
	** [[WAV]]: Values written to ID3 chunk.		** [[WAV]]: Values written to ID3 chunk.
	** [[AIFF]]: Values written to ID3 chunk.		** [[AIFF]]: Values written to ID3 chunk.
			** [[Matroska]]: Values written to container tags.
	** Modules ([[MOD]] etc.): Optionally saved into [[APEv2]] tags.		** Modules ([[MOD]] etc.): Optionally saved into [[APEv2]] tags.
	** Any non-taggable format or format supported by FFmpeg can store RG values in a database or external tag with a component.		** Any non-taggable format or format supported by FFmpeg can store RG values in a database or external tag with a component.
	** A separate function can be invoked to apply the tagged Track or Album Gain to the global gain fields in MP3, ~~MP4~~ (~~AAC~~), or Opus files, and rewrite any existing tags to account for the peak change and compensate for the difference from 89 dB. The 89 dB reference level for tags isn't configurable, but the reference level applied to the global gain fields is.		** A separate function can be invoked to apply the tagged Track or Album Gain to the global gain fields in MP3, AAC (in container), or Opus files, and rewrite any existing tags to account for the peak change and compensate for the difference from 89 dB. The 89 dB reference level for tags isn't configurable, but the reference level applied to the global gain fields is.
	** Can automatically copy Track or Album gain values to Apple's SoundCheck tag in MP4 files or any format that supports ID3v2 to effectively add ReplayGain support to Apple's players.		** Can automatically copy Track or Album gain values to Apple's SoundCheck tag in MP4 files or any format that supports ID3v2 to effectively add ReplayGain support to Apple's players.
	* https://foobar2000.org/		* https://foobar2000.org/