Hydrogenaudio Knowledgebase - User contributions [en]

Replay Gain

2006-02-18T18:32:06Z

Pmmagic: /* Portable devices */

=Introduction=

'''Replaygain''' is the name of a technique invented to achieve the same playback volume of audio files. It specifies the reference level of 89dB and an algorithm to measure the '''perceived''' loudness of audio data.

Replaygain is more than mere [[Normalization|normalization]]. In normalization, you merely ensure that the peak amplitude reaches a certain level. However, songs with 'spiky' waveforms might not be amplified enough. The replaygain technique measures the ''effective'' (i.e. RMS) power of the waveform, and amplifies the waveform accordingly. The result is that replaygained waveforms are usually more uniformly amplified that normalized waveforms.

=Implementations=

There are different replaygain implementations, each with its own uses and strength. Most of them use [[meta data]] to indicate the level of the volume change (Volume is adjusted on playback; needs player/decoder support) others modify the Audio Data itself. Generally it is recommended to use an implementation which uses meta data and does not touch the audio itself.

In a meta data based solution, information on both types of replaygain can be stored, and the desired playback effect can be switched back and forth in the appropriate player. However, if the audio data is permanently modified, only one type of replaygain can be chosen. Furthermore, if the audio data is modified, you may not be able to restore the original data, especially if the replaygain technique produces a negative amplification.

Replaygain has significant advantages over [[Normalization|normalizing]]. It allows the loudness of a song to be consistant over an entire collection of audio, similar like normalizing (this is called 'Track Gain', or 'Radio Gain' in earlier parlance). However, it also allows the loudness of an album to be consistant over a entire music collection, allowing the dynamics of album to remain (This is called 'Album Gain', or 'Audiophile Gain' in earlier parlance). This is usually very important in classical CDs, as there may be quiet segments and loud segments written into different tracks.

==MP3Gain==

* Format: [[MP3]]
* Method: Audio or Meta
* Limitations: Limited to 1.5dB steps in Audio Data mode
* http://mp3gain.sourceforge.net/

==[[LAME]]==

* Method: Header ([http://gabriel.mp3-tech.org/mp3infotag.html mp3infotag])
* Notes: Added during encoding; not supported by any player yet; Track Gain only
* http://lame.sourceforge.net/

==[[MPC]] replaygain==

* Method: Header (similar to Meta data method)
* Notes: Replaygain values are stored in the header and replaygain is part of the Musepack specifications; therefore any Musepack decoder that does not support replaygain can be considered broken.
* http://rarewares.org/mpc.html

==Vorbisgain==

* Format: [[Ogg Vorbis]]
* Method: Meta (in [[Vorbis comment]])
* http://www.sjeng.org/vorbisgain.html

==FLAC/metaflac==

* Format: FLAC
* Method: Meta (in [[Vorbis comment]])
* http://flac.sf.net

==Wavegain==

* Format: waveform
* Method: Audio
* Limitations: Irreversible
* http://www.rarewares.org/files/others/wavegain.zip

==[[foobar2000]] replaygain scanner==

* Format:
** [[MP3]]: Values written to [[APEv2]] or [[ID3v2]] tags.
** [[MPC]]: Values written to header.
** [[Ogg Vorbis]]: Values written to [[Vorbis comment]].
** [[WavPack]]: 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).
** [[FLAC]]: Values written to [[Vorbis comment]].
** [[APE]]: Values written to [[APEv2]] tags.
** [[WAV]]: Optionally saved into [[APEv2]] tags; otherwise the foobar2000 database is used.
** Modules ([[MOD]] etc.): Optionally saved into [[APEv2]] tags; otherwise the foobar2000 database is used.
** All other formats are supported but the replaygain values are saved to the foobar2000 database.

* You can also choose to only have the replaygain values saved in the foobar2000 database and leave the files untouched.

* http://foobar2000.org

==[[MediaMonkey]]==

* Format:
** [[MP3]]: Values written to [[APEv2]] or [[ID3v2]] tags.
** [[Ogg Vorbis]]: Values written to [[Vorbis comment]].
** [[WMA]]: Values stored in its database.
** [[FLAC]]: Values written to [[Vorbis comment]].
** [[APE]]: Values written to [[APEv2]] tags.
** [[WAV]]: Optionally saved into [[APEv2]] tags; otherwise the foobar2000 database is used.
* Does not support Album/Audiophile replaygain
* Also capable of (irreversibly) changing the volume of MP3 tracks
* http://www.mediamonkey.com

=Players support=

Replaygain being present in the specs of FLAC, MPC, and APE formats, any player that support those formats usually support replaygain.

The situation with MP3 is rather different, as it was not part of the MP3 specs. The APEv2 tags metadata implementation is somewhat becoming the de-facto standard.

==Windows==

* [[Foobar2000]] supports replaygain in all possible aspects.
* [[Winamp]]
** MP3 replaygain support with adequate plugins (e.g. [http://www.aikis.or.jp/~otachan/in_mpg123.html Otachan's in_mpg123] - if you can't read japanese, you can find details [http://www.hydrogenaudio.org/forums/index.php?showtopic=18530 in this thread])
** [[Ogg Vorbis]] replaygain support
* [[MediaMonkey]] supports track replaygain only
* [[XMPlay]] recently implemented replaygain

''...and probably others.''

==Linux==

* [[XMMS]]. Reads replaygain from [[FLAC]], [[MPC]], [[Ogg Vorbis]] ..
:For [[MP3]], use the CVS version of the [http://xmms-mad.sourceforge.net/ xmms-mad] mp3 plugin (it's not yet released as binary, furthermore not available in distribs' versions for now. Meanwhile binaries are available here: [http://perso.crans.org/~krempp/xmms-mad/ custom binaries])
* [[amaroK]]. By using the amaroK-script [http://kde-apps.org/content/show.php?content=26073 ReplayGain]
:And possibly others, since [http://developer.kde.org/~wheeler/taglib.html TagLib] added support for [[APEv2]] tags in [[MP3]] files, players using this library (like [[amaroK]] and [[JuK]]) might support that kind of replaygain tags in the near future.
* [http://www.sacredchao.net/quodlibet Quod Libet] reads replaygain from [[Ogg Vorbis]], [[FLAC]], and [[MPC]]
:Requires support to be enabled (via the appropriate python bindings and libraries) for the above formats. Does not support replaygain values stored in [[APEv2]] tags in [[MP3]]s.

==Portable devices==

Current development builds of [http://www.rockbox.org/ Rockbox] for the iRiver H100 and H300 series players support replaygain for some encoder formats. This is a rapidly evolving feature. There are no other portable players known to support replaygain.

The iPod features ''Soundcheck'', which seems to produce roughly the same normalization gains as replaygain, but doesnt provide an Album Gain.

=Additional reading=
* [http://replaygain.hydrogenaudio.org Original replaygain website]

Rockbox

2006-02-18T18:26:21Z

Pmmagic: /* H1xx/H3xx */

[[Image:Rockboxlogo.png|right]]

'''Rockbox''' is a [[GPL]]-compliant [[open source]] operating system for portable digital audio players (DAPs). The Rockbox Project began in 2002 and was first implemented on the [[Archos]] Studio DAP because of owner frustration with severe limitations in the manufacturer-supplied user interface and device operations.

Rockbox can completely replace the host device's operating system firmware and has matured to become an extensible, flexible platform that provides a plug-in architecture for adding PDA functionality, applications, utilities, and games, and has also managed to retrofit video playback functionality onto DAPs first released in mid-2000. Recently, Rockbox now includes a voice-driven user-interface suitable for operation by blind and visually impaired users.

Although Rockbox's official title is "Rockbox: Open Source Jukebox Firmware", in many instances it is not actually installed to (or run from) flash memory. Instead a minimal bootloader is installed in the supported device's flash which is capable of either loading Rockbox from the hard disk or, alternately, the original factory firmware.

==Archos devices==

Rockbox was first designed for the Archos series of [[MP3]] players and player/recorders. These devices have relatively weak main CPUs and instead offload music playback to dedicated hardware MP3 decoding chips. Rockbox, therefore, was unable to significantly alter playback capabilities. Instead, it offered a greatly improved user interface and added plugin functionality not present in the factory firmware.

Rockbox is capable of being permanently flashed into flash memory on the Archos devices, making it a literal firmware replacement.

==iRiver devices==

===H1xx/H3xx===
Beginning in late 2004, an effort began to port Rockbox to the Motorola ColdFire-powered devices manufactured by [[iRiver]], focusing on the H1xx series of hard drive players (H110/H120/H140). These devices perform audio decoding in software, allowing Rockbox to potentially support many more audio codecs than the original firmware as well as bringing the extensibility and increased functionality already present in the Archos ports. Rockbox is run from the hard disk on these devices, after being started with a custom bootloader.

As of February 2006, the iRiver port is in pre-release advanced testing. Most major functions are fully supported including [[gapless|gapless playback]], [[ReplayGain]], "on the fly" (OTF) playlists, FM radio, remote control, custom UI themes and [[WAV]] recording (including FM recording). Supported playback codecs include: MPEG audio ([[MP3]]/[[MP2]]), [[Ogg Vorbis]], [[Musepack]], [[AC3]], [[AAC]] (experimental, not yet real-time), [[FLAC]], [[Shorten]], [[Apple Lossless]], [[WavPack]] and uncompressed WAV audio. Plugins include a colour [[JPEG]] viewer, the Rockboy Game Boy emulator (not yet real-time) and several games.

A port is underway for the IRiver H3xx series which is similar to the H1xx except for the addition of a color screen, USB host capability and the removal of the H1xx digital optical in/out jacks. As of January 2006, the port is in public testing. Most basic functions work (including playback). Support for a color UI is currently in active development.

===iFP-xxx===
A port to the iFP-xxx flash-based devices (starting with the iFP-790) is underway. When completed it will be the first pure flash device to be supported by Rockbox. The port is currently suitable for developers only.

===H10===
It has been recently discovered that the iRiver H10 Series|iRiver H10 uses the same main CPU as the iPod, meaning that it may be possible to port Rockbox using much of the code developed for the iPod port. It is not yet known whether an H10 port will ever officially be started.

==iAudio devices==
A port to the [[iAudio]] X5 hard drive player (also powered by the Motorola ColdFire chip) is underway. The port is currently suitable for developers only.

==Apple devices==

In November 2005, work began on a port of Rockbox to Apple iPod portable players. As of January 2006, support is available for the the iPod photo and nano with work to support greyscale models (e.g. iPod mini) currently underway.

==Neuros devices==

==External links==
* [http://www.rockbox.org/ The Rockbox Project]

<font style="color:green;">''~ Text taken from [http://en.wikipedia.org/wiki/Rockbox Wikipedia entry for Rockbox]''</font>

Rockbox

2006-02-18T18:25:33Z

Pmmagic:

[[Image:Rockboxlogo.png|right]]

'''Rockbox''' is a [[GPL]]-compliant [[open source]] operating system for portable digital audio players (DAPs). The Rockbox Project began in 2002 and was first implemented on the [[Archos]] Studio DAP because of owner frustration with severe limitations in the manufacturer-supplied user interface and device operations.

Rockbox can completely replace the host device's operating system firmware and has matured to become an extensible, flexible platform that provides a plug-in architecture for adding PDA functionality, applications, utilities, and games, and has also managed to retrofit video playback functionality onto DAPs first released in mid-2000. Recently, Rockbox now includes a voice-driven user-interface suitable for operation by blind and visually impaired users.

Although Rockbox's official title is "Rockbox: Open Source Jukebox Firmware", in many instances it is not actually installed to (or run from) flash memory. Instead a minimal bootloader is installed in the supported device's flash which is capable of either loading Rockbox from the hard disk or, alternately, the original factory firmware.

==Archos devices==

Rockbox was first designed for the Archos series of [[MP3]] players and player/recorders. These devices have relatively weak main CPUs and instead offload music playback to dedicated hardware MP3 decoding chips. Rockbox, therefore, was unable to significantly alter playback capabilities. Instead, it offered a greatly improved user interface and added plugin functionality not present in the factory firmware.

Rockbox is capable of being permanently flashed into flash memory on the Archos devices, making it a literal firmware replacement.

==iRiver devices==

===H1xx/H3xx===
Beginning in late 2004, an effort began to port Rockbox to the Motorola ColdFire-powered devices manufactured by [[iRiver]], focusing on the H1xx series of hard drive players (H110/H120/H140). These devices perform audio decoding in software, allowing Rockbox to potentially support many more audio codecs than the original firmware as well as bringing the extensibility and increased functionality already present in the Archos ports. Rockbox is run from the hard disk on these devices, after being started with a custom bootloader.

As of February 2006, the iRiver port is in pre-release advanced testing. Most major functions are fully supported including [[gapless|gapless playback]], [[ReplayGain]], "on the fly" (OTF) playlists, FM radio, remote control, custom UI themes and [[WAV]] recording (including FM recording). Supported playback codecs include: MPEG audio ([[MP3]]/[[MP2]]), [[Ogg Vorbis]], [[Musepack]], [[AC3]], [[AAC]] (experimental, not yet real-time), [[FLAC]], [[Shorten]], [[Apple Lossless]], [[WavPack]] and uncompressed WAV audio. Plugins include a colour[[JPEG]] viewer, the Rockboy Game Boy emulator (not yet real-time) and several games.

A port is underway for the IRiver H3xx series which is similar to the H1xx except for the addition of a color screen, USB host capability and the removal of the H1xx digital optical in/out jacks. As of January 2006, the port is in public testing. Most basic functions work (including playback). Support for a color UI is currently in active development.

===iFP-xxx===
A port to the iFP-xxx flash-based devices (starting with the iFP-790) is underway. When completed it will be the first pure flash device to be supported by Rockbox. The port is currently suitable for developers only.

===H10===
It has been recently discovered that the iRiver H10 Series|iRiver H10 uses the same main CPU as the iPod, meaning that it may be possible to port Rockbox using much of the code developed for the iPod port. It is not yet known whether an H10 port will ever officially be started.

==iAudio devices==
A port to the [[iAudio]] X5 hard drive player (also powered by the Motorola ColdFire chip) is underway. The port is currently suitable for developers only.

==Apple devices==

In November 2005, work began on a port of Rockbox to Apple iPod portable players. As of January 2006, support is available for the the iPod photo and nano with work to support greyscale models (e.g. iPod mini) currently underway.

==Neuros devices==

==External links==
* [http://www.rockbox.org/ The Rockbox Project]

<font style="color:green;">''~ Text taken from [http://en.wikipedia.org/wiki/Rockbox Wikipedia entry for Rockbox]''</font>