MP3Gain is an
audio normalization
Audio normalization is the application of a constant amount of gain to an audio recording to bring the amplitude to a target level (the norm). Because the same amount of gain is applied across the entire recording, the signal-to-noise ratio and ...
software tool. The tool is available on
multiple platforms and is
free software
Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, no ...
. It analyzes the
MP3
MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere. Origin ...
and reversibly changes its volume. The volume can be adjusted for single files or as album where all files would have the same perceived
loudness
In acoustics, loudness is the subjectivity, subjective perception of sound pressure. More formally, it is defined as, "That attribute of auditory sensation in terms of which sounds can be ordered on a scale extending from quiet to loud". The rel ...
. It is an implementation of
ReplayGain
ReplayGain is a proposed technical standard published by David Robinson in 2001 to measure and normalize the perceived loudness of audio in computer audio formats such as MP3 and Ogg Vorbis. It allows media players to normalize loudness for indi ...
. In 2015 Debian and Ubuntu removed it from their repositories due to a lack of an active maintainer.
MP3Gain Technical details
MP3Gain first computes the desired
gain
Gain or GAIN may refer to:
Science and technology
* Gain (electronics), an electronics and signal processing term
* Antenna gain
* Gain (laser), the amplification involved in laser emission
* Gain (projection screens)
* Information gain in de ...
(volume adjustment), either per track or per album, using the ReplayGain algorithm. It then modifies the overall volume scale factor in each MP3 frame, and writes undo information as a tag (in
APEv2
APE tags comprise one extant convention used to store information ( metadata) about a given digital audio file. Each APE tag constitutes a discrete element that describes a single attribute of the file's contents.
Each consists of a key/value ...
, or
ID3v2
ID3 is a metadata container most often used in conjunction with the MP3 audio file format. It allows information such as the title, artist, album, track number, and other information about the file to be stored in the file itself.
There are two ...
format) making this a reversible process. The scale factor modification can be reversed using the information in the added tag and the tag may be removed. MP3Gain does not introduce any
digital generation loss
Generation loss is the loss of quality between subsequent copies or transcodes of data. Anything that reduces the quality of the representation when copying, and would cause further reduction in quality on making a copy of the copy, can be consi ...
because it does not
decode and re-encode the file.
AACGain Technical details
MP3Gain is unable to change the volume on AAC or MP4 files. A mod called AACGain exists that can be used as super-set drop-in replacement
in most front-ends originally created for MP3Gain. The audio file must be AAC inside a
MP4 format container and not raw
AAC
AAC may refer to:
Aviation
* Advanced Aircraft, a company from Carlsbad, California
* Alaskan Air Command, a radar network
* American Aeronautical Corporation, a company from Port Washington, New York
* American Aviation, a company from Cleveland, ...
data file.
References
External links
* {{official website, https://sourceforge.net/projects/mp3gain/files/
MP3Gain Express, the Mac version's webpageeasyMP3Gain, a Linux front-end for MP3GainJavaMP3Gain, a java front-end for MP3Gain
Free software programmed in C
Free audio software
Cross-platform free software
Free multilingual software