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Gapless playback

November 03, 2023

Gapless playback is the uninterrupted playback of consecutive audio tracks, such that relative time distances in the original audio source are preserved over track boundaries on playback. For this to be useful, other artifacts (than timing-related ones) at track boundaries should not be severed either. Gapless playback is common with compact discs, gramophone records, or tapes, but is not always available with other formats that employ compressed digital audio. The absence of gapless playback is a source of annoyance to listeners of music where tracks are meant to segue into each other, such as some classical music (opera in particular), progressive rock, concept albums, electronic music, and live recordings with audience noise between tracks.

Causes of gaps edit

Playback latency edit

Various software, firmware, and hardware components may add up to a substantial delay associated with starting playback of a track. If not accounted for, the listener is left waiting in silence as the player fetches the next file (see harddisk access time), updates metadata, decodes the whole first block, before having any data to feed the hardware buffer. The gap can be as much as half a second or more — very noticeable in "continuous" music such as certain classical or dance genres. In extreme cases, the hardware is even reset between tracks, creating a very short "click".

To account for the whole chain of delays, the start of the next track should ideally be readily decoded before the currently playing track finishes. The two decoded pieces of audio must be fed to the hardware continuously over the transition, as if the tracks were concatenated in software.

Many older audio players on personal computers do not implement the required buffering to play gapless audio. Some of these rely on third-party gapless audio plug-ins to buffer output. Most recent players and newer versions of old players now support gapless playback directly.

Compression artifacts edit

Lossy audio compression schemes that are based on overlapping time/frequency transforms add a small amount of padding silence to the beginning and end of each track. These silences increase the playtime of the compressed audio data.[1] If not trimmed off upon playback, the two silences played consecutively over a track boundary will appear as a pause in the original audio content. Lossless formats are not prone to this problem.

For some audio formats (e.g. Ogg Vorbis), where the start and end are precisely defined, the padding is implicitly trimmed off in the decoding process. Other formats may require extra metadata for the player to achieve the same. The popular MP3 format defines no way to record the amount of delay or padding for later removal.[notes 1] Also, the encoder delay may vary from encoder to encoder, making automatic removal difficult.[2] Even if two tracks are decompressed and merged into a single track, a pause will usually remain between them.

CD recorded in TAO mode edit

Main article: Optical disc recording modes

Audio-CDs can be recorded in either disc at once (DAO) or track at once (TAO) mode. The latter is more flexible, but has the drawback of inserting approximately 2 seconds of silence between tracks.Disc at once (DAO) mode allows you to record the entire CD in one continuous session, without any pauses between tracks.[3] This mode is suitable when you want a seamless playback experience with no interruptions between songs. DAO is commonly used for live recordings, DJ mixes, or concept albums where tracks blend into each other.[4]

Ways to eliminate the gaps edit

Precise gapless playback edit

As opposed to heuristic techniques, what is often meant by precise gapless playback, is that playback timing is guaranteed to be identical to the source. By this definition, a precise gapless player is not allowed to introduce either gaps or overlaps (crossfading) between successive tracks, and is not allowed to use guesswork.

Apart from accounting for playback latency, the preciseness here lies in treating lossless data as-is, and removing the correct amount of padding from lossy data. This is not possible for file formats with loosely defined encoder specifications and no metadata and therefore no way for encoders to record the duration of extraneous silence.

Approximate methods edit

Heuristics are used by some music players to detect silence between tracks and trim the audio as necessary on playback. Due to the loss of time resolution of lossy compression, this method is inexact. In particular, the silence is not exactly zero. If the silence threshold is too low, some silences go undetected. Too high, and entire sections of quiet music at the beginning or end of a track may be removed.

Digital signal processing (DSP) algorithms can also be used to crossfade between tracks. This eliminates gaps that some listeners find distracting, but also greatly alters the audio signal, which may have undesirable effects on the listening experience. Some listeners dislike these effects more than the gap they attempt to remove. For example, crossfading is inappropriate for files that are already gapless, in which case the transition may feel artificially short and disturb the rhythm.[5] Also, depending on the length of untrimmed silence and the particular crossfader, it may cause a large volume drop.

These methods defeat the purpose of intentional spacing between tracks. Not all albums are mix albums; perhaps more typically, there is an aesthetic pause between unrelated tracks. Also, the artist may intentionally leave in silences for dramatic effect, which should arguably be preserved regardless of whether there is a track boundary there.

Compared to precise gapless playback, these methods are a different approach to erroneous silence in audio files, but other required features are the same. However, this approach requires more computation. In portable digital audio players, this means a reduced playing time on batteries.

User workarounds edit

A common workaround is to encode consecutive tracks as one single file, relying on cue sheets (or something similar) for navigation. While this method results in gapless playback within consecutive tracks, it can be unwieldy because of the possibly large size of the resulting compressed file. Furthermore, unless the playback software or hardware can recognize the cue sheets, navigating between tracks may be difficult.

It may be possible to add gapless metadata to existing files. If the encoder is known, it is possible to guess the encoder delay. Also, if the compression was performed on CD audio, the original playback length will be an integer multiple of 588 samples, the size of one CD sector. Thus the total playback time can also be guessed. Adding such information to audio files will enable precise gapless playback in players that support this.

Prerequisites edit

Format support edit

Since lossless data compression excludes the possibility of the introduction of padding, all lossless audio file formats are inherently gapless.

These lossy audio file formats have provisions for gapless encoding:

Some other formats do not officially support gapless encoding, but some implementations of encoders or decoders may handle gapless metadata.

  • LAME-encoded MP3 can be gapless with players that support the LAME Mp3 info tag.[7]
  • AAC in MP4 encoded with Nero Digital from Nero AG can be gapless with foobar2000, latest XMMS2, and iTunes 7.1.1.5 through 11.4.
  • AAC in MP4 encoded with iTunes (current and previous versions) is gapless in iTunes 7.0 through 11.4, 2nd generation iPod nanos, all video-capable iPods with the latest firmware, and recent versions of foobar2000.[8][irrelevant citation]
  • iTunes-encoded MP3 is gapless when played back in iTunes 7.0 through 11.4, 2nd generation iPod nanos, and all video-capable iPods with the latest firmware.
  • Windows Media Audio encoded with Windows Media Player 9 can be gapless with Windows Media Player 9 and onwards.
  • Windows Media Audio encoded with Sound Player Lilith can be gapless with latest Sound Player Lilith onwards.[9]
  • ATRAC on MiniDisc is gapless through the use of TOC (Table of Contents).

Player support edit

Optimal solutions:

Hardware edit

  • Apple:
  • Archos Gmini XS202S
  • Cowon S9 supports gapless playback without software dependency since 2.31b firmware. Most newer Cowon players support gapless playback right out of the box (J3, X7, iAudio 9)
  • Linn Products DS network players
  • All players in the Logitech/Slim Devices Squeezebox range support gapless playback for all gapless formats (lame MP3, FLAC, Vorbis, etc.). Crossfading is also optionally available.
  • Microsoft Zune supports gapless playback with Zune 2.5 or later firmware, though some bugs remain and occasionally small pops or skips can be heard.[11]
  • Panasonic RX-D55AEG-K, a portable radio recorder with CD player
  • Rio Karma gapless hardware player with no software dependency (FLAC, Ogg, MP3, WMA), first portable DAP with the feature[12]
  • Roberts Sound 48, a clock radio with CD player
  • Rockbox for various digital audio players.
  • Sony:
    • MiniDisc Walkman supports gapless playback (including non-Sony Walkman MiniDisc players)
    • CD Walkman (such as D-NE330) supports gapless playback of ATRAC-encoded CDs
    • VAIO Pocket supports gapless playback (through a firmware update) of ATRAC files
    • Network Walkman NW-HDx and NW-A (1x00, 3000, 60x, 80x) DAPs supports gapless playback of ATRAC files - after this Walkman DAPs lost the feature when ATRAC support ceased, but continued in Japan where players still came with ATRAC. Gapless playback returned outside Japan 5 years later with Walkman NWZ-F80x through the FLAC format.[13]
  • Trekstor Vibes gapless hardware player with no software dependency
  • Victor Alneo V Series and C Series[14][15]

Software edit

Alternative or partial solutions:

  • XMMS2 – has native support for gapless MP3 / Ogg Vorbis and FLAC

See also edit

  • Segue, the technique in classical music

References edit

  1. ^ Taylor, Mark (2003). "LAME Technical FAQ". Retrieved 2006-07-06.
  2. ^ Robinson, David (2001). "lame v3.81 and 3.87 beta mp3 decoding quality test results". Retrieved 2006-08-24. Features a table of encoder delay values.
  3. ^ Taimoor, Taimoor (2023-06-15). "Gapless Playback/Cross Fade".
  4. ^ Hassan, Taimoor (2023-06-08). "What Is & How To Enable Gapless Playback Spotify 2023?". spotifmania.com. Retrieved 2023-06-19.
  5. ^ "256734 – precise gapless playback". bugs.kde.org. Retrieved 7 December 2017.
  6. ^ "Speex News". 2004-07-28. Retrieved 2008-04-25.
  7. ^ "LAME Technical FAQ". June 2000. Retrieved 2012-01-28.
  8. ^ "Guides and Sample Code". developer.apple.com. Retrieved 7 December 2017.
  9. ^ "再生制御". www.project9k.jp. Retrieved 7 December 2017.
  10. ^ a b c . Apple Inc. Archived from the original on 2008-05-08. Retrieved 2008-05-13.
  11. ^ "Thread on gapless playback on Zune HD". 2010-02-25. Retrieved 2010-05-04.
  12. ^ "Rio Karma 20Gb MP3 Player". 24 April 2004.
  13. ^ "Sony NWZ-F806 Specification Guide - Page 1 of 4".
  14. ^ Ittousai. "ビクターAlneo にギャップレス再生・AAC対応の新モデル - Engadget Japanese". Retrieved 7 December 2017.
  15. ^ "【新製品レビュー】". av.watch.impress.co.jp. Retrieved 7 December 2017.
  16. ^ "Thread on Gapless Playback on Amarok Mailing List". 2006-09-06. Retrieved 2007-01-19.
  17. ^ "[Implemented] Gapless Playback". 23 December 2018.

Notes edit

  1. ^ Despite this, there are encoders which store the amount of padding introduced in metadata to allow gapless playback. This can only be used if the playback software is able to interpret the metadata information.
  2. ^ a b c Vorbis and Speex feature gapless support through the Ogg layer. The reference implementation of Speex did not initially ship with gapless metadata support.

External links edit

November 03, 2023
gapless, playback, uninterrupted, playback, consecutive, audio, tracks, such, that, relative, time, distances, original, audio, source, preserved, over, track, boundaries, playback, this, useful, other, artifacts, than, timing, related, ones, track, boundaries. Gapless playback is the uninterrupted playback of consecutive audio tracks such that relative time distances in the original audio source are preserved over track boundaries on playback For this to be useful other artifacts than timing related ones at track boundaries should not be severed either Gapless playback is common with compact discs gramophone records or tapes but is not always available with other formats that employ compressed digital audio The absence of gapless playback is a source of annoyance to listeners of music where tracks are meant to segue into each other such as some classical music opera in particular progressive rock concept albums electronic music and live recordings with audience noise between tracks Contents 1 Causes of gaps 1 1 Playback latency 1 2 Compression artifacts 1 3 CD recorded in TAO mode 2 Ways to eliminate the gaps 2 1 Precise gapless playback 2 2 Approximate methods 2 3 User workarounds 3 Prerequisites 3 1 Format support 3 2 Player support 3 2 1 Hardware 3 2 2 Software 4 See also 5 References 5 1 Notes 6 External linksCauses of gaps editPlayback latency edit Various software firmware and hardware components may add up to a substantial delay associated with starting playback of a track If not accounted for the listener is left waiting in silence as the player fetches the next file see harddisk access time updates metadata decodes the whole first block before having any data to feed the hardware buffer The gap can be as much as half a second or more very noticeable in continuous music such as certain classical or dance genres In extreme cases the hardware is even reset between tracks creating a very short click To account for the whole chain of delays the start of the next track should ideally be readily decoded before the currently playing track finishes The two decoded pieces of audio must be fed to the hardware continuously over the transition as if the tracks were concatenated in software Many older audio players on personal computers do not implement the required buffering to play gapless audio Some of these rely on third party gapless audio plug ins to buffer output Most recent players and newer versions of old players now support gapless playback directly Compression artifacts edit Lossy audio compression schemes that are based on overlapping time frequency transforms add a small amount of padding silence to the beginning and end of each track These silences increase the playtime of the compressed audio data 1 If not trimmed off upon playback the two silences played consecutively over a track boundary will appear as a pause in the original audio content Lossless formats are not prone to this problem For some audio formats e g Ogg Vorbis where the start and end are precisely defined the padding is implicitly trimmed off in the decoding process Other formats may require extra metadata for the player to achieve the same The popular MP3 format defines no way to record the amount of delay or padding for later removal notes 1 Also the encoder delay may vary from encoder to encoder making automatic removal difficult 2 Even if two tracks are decompressed and merged into a single track a pause will usually remain between them CD recorded in TAO mode edit Main article Optical disc recording modes Audio CDs can be recorded in either disc at once DAO or track at once TAO mode The latter is more flexible but has the drawback of inserting approximately 2 seconds of silence between tracks Disc at once DAO mode allows you to record the entire CD in one continuous session without any pauses between tracks 3 This mode is suitable when you want a seamless playback experience with no interruptions between songs DAO is commonly used for live recordings DJ mixes or concept albums where tracks blend into each other 4 Ways to eliminate the gaps editPrecise gapless playback edit As opposed to heuristic techniques what is often meant by precise gapless playback is that playback timing is guaranteed to be identical to the source By this definition a precise gapless player is not allowed to introduce either gaps or overlaps crossfading between successive tracks and is not allowed to use guesswork Apart from accounting for playback latency the preciseness here lies in treating lossless data as is and removing the correct amount of padding from lossy data This is not possible for file formats with loosely defined encoder specifications and no metadata and therefore no way for encoders to record the duration of extraneous silence Approximate methods edit Heuristics are used by some music players to detect silence between tracks and trim the audio as necessary on playback Due to the loss of time resolution of lossy compression this method is inexact In particular the silence is not exactly zero If the silence threshold is too low some silences go undetected Too high and entire sections of quiet music at the beginning or end of a track may be removed Digital signal processing DSP algorithms can also be used to crossfade between tracks This eliminates gaps that some listeners find distracting but also greatly alters the audio signal which may have undesirable effects on the listening experience Some listeners dislike these effects more than the gap they attempt to remove For example crossfading is inappropriate for files that are already gapless in which case the transition may feel artificially short and disturb the rhythm 5 Also depending on the length of untrimmed silence and the particular crossfader it may cause a large volume drop These methods defeat the purpose of intentional spacing between tracks Not all albums are mix albums perhaps more typically there is an aesthetic pause between unrelated tracks Also the artist may intentionally leave in silences for dramatic effect which should arguably be preserved regardless of whether there is a track boundary there Compared to precise gapless playback these methods are a different approach to erroneous silence in audio files but other required features are the same However this approach requires more computation In portable digital audio players this means a reduced playing time on batteries User workarounds edit A common workaround is to encode consecutive tracks as one single file relying on cue sheets or something similar for navigation While this method results in gapless playback within consecutive tracks it can be unwieldy because of the possibly large size of the resulting compressed file Furthermore unless the playback software or hardware can recognize the cue sheets navigating between tracks may be difficult It may be possible to add gapless metadata to existing files If the encoder is known it is possible to guess the encoder delay Also if the compression was performed on CD audio the original playback length will be an integer multiple of 588 samples the size of one CD sector Thus the total playback time can also be guessed Adding such information to audio files will enable precise gapless playback in players that support this Prerequisites editThis section may contain indiscriminate excessive or irrelevant examples Please improve the article by adding more descriptive text and removing less pertinent examples See Wikipedia s guide to writing better articles for further suggestions October 2018 Format support edit Since lossless data compression excludes the possibility of the introduction of padding all lossless audio file formats are inherently gapless These lossy audio file formats have provisions for gapless encoding Musepack Ogg Vorbis notes 2 Speex notes 2 6 Opus notes 2 Some other formats do not officially support gapless encoding but some implementations of encoders or decoders may handle gapless metadata LAME encoded MP3 can be gapless with players that support the LAME Mp3 info tag 7 AAC in MP4 encoded with Nero Digital from Nero AG can be gapless with foobar2000 latest XMMS2 and iTunes 7 1 1 5 through 11 4 AAC in MP4 encoded with iTunes current and previous versions is gapless in iTunes 7 0 through 11 4 2nd generation iPod nanos all video capable iPods with the latest firmware and recent versions of foobar2000 8 irrelevant citation iTunes encoded MP3 is gapless when played back in iTunes 7 0 through 11 4 2nd generation iPod nanos and all video capable iPods with the latest firmware Windows Media Audio encoded with Windows Media Player 9 can be gapless with Windows Media Player 9 and onwards Windows Media Audio encoded with Sound Player Lilith can be gapless with latest Sound Player Lilith onwards 9 ATRAC on MiniDisc is gapless through the use of TOC Table of Contents Player support edit Optimal solutions Hardware edit Apple iPod classic supports gapless playback of MP3s and AACs from the fifth generation onward 10 iPod nano second generation and later 10 iPod Touch 10 Archos Gmini XS202S Cowon S9 supports gapless playback without software dependency since 2 31b firmware Most newer Cowon players support gapless playback right out of the box J3 X7 iAudio 9 Linn Products DS network players All players in the Logitech Slim Devices Squeezebox range support gapless playback for all gapless formats lame MP3 FLAC Vorbis etc Crossfading is also optionally available Microsoft Zune supports gapless playback with Zune 2 5 or later firmware though some bugs remain and occasionally small pops or skips can be heard 11 Panasonic RX D55AEG K a portable radio recorder with CD player Rio Karma gapless hardware player with no software dependency FLAC Ogg MP3 WMA first portable DAP with the feature 12 Roberts Sound 48 a clock radio with CD player Rockbox for various digital audio players Sony MiniDisc Walkman supports gapless playback including non Sony Walkman MiniDisc players CD Walkman such as D NE330 supports gapless playback of ATRAC encoded CDs VAIO Pocket supports gapless playback through a firmware update of ATRAC files Network Walkman NW HDx and NW A 1x00 3000 60x 80x DAPs supports gapless playback of ATRAC files after this Walkman DAPs lost the feature when ATRAC support ceased but continued in Japan where players still came with ATRAC Gapless playback returned outside Japan 5 years later with Walkman NWZ F80x through the FLAC format 13 Trekstor Vibes gapless hardware player with no software dependency Victor Alneo V Series and C Series 14 15 Software edit Amarok for Linux 16 AIMP for windows Audacious for Linux Banshee for Linux Clementine cross platform cmus for Linux and BSD Cog for OS X DeaDBeeF for Linux foobar2000 for Windows and Mac Groove Music for Windows 10 iTunes 7 0 through 11 4 supported as default gapless playback on Macintosh and Windows without having to combine tracks during encoding a limitation of previous releases Some users in unusual situations have complained that the one time analysis is a system intensive process that can stall or crash computers JRiver Media Center for Windows KODI for Windows Linux OS X Android and others mplayer2 for Linux OS X and Windows supports gapless playback of flac when used with option gapless audio mpv media player for BSD Linux macOS Windows MusicBee for Windows Music On Console for Linux and other Unix like platforms Music Player Daemon for Linux and other Unix like platforms Plex for all supported platforms either through the platform player or PlexAmp 17 Qlab for OS X Quod Libet multi platform Rhythmbox for Linux Winamp supports gapless playback for MP3 M4A AAC Ogg Vorbis and FLAC files since version 5 3 Windows Media Player has supported gapless ripping and playback of WMA since Windows Media 9 Available on all current Windows machines XMPlay supports gapless playback for all format filesAlternative or partial solutions XMMS2 has native support for gapless MP3 Ogg Vorbis and FLACSee also editSegue the technique in classical musicReferences edit Taylor Mark 2003 LAME Technical FAQ Retrieved 2006 07 06 Robinson David 2001 lame v3 81 and 3 87 beta mp3 decoding quality test results Retrieved 2006 08 24 Features a table of encoder delay values Taimoor Taimoor 2023 06 15 Gapless Playback Cross Fade Hassan Taimoor 2023 06 08 What Is amp How To Enable Gapless Playback Spotify 2023 spotifmania com Retrieved 2023 06 19 256734 precise gapless playback bugs kde org Retrieved 7 December 2017 Speex News 2004 07 28 Retrieved 2008 04 25 LAME Technical FAQ June 2000 Retrieved 2012 01 28 Guides and Sample Code developer apple com Retrieved 7 December 2017 再生制御 www project9k jp Retrieved 7 December 2017 a b c What is Gapless Playback Apple Inc Archived from the original on 2008 05 08 Retrieved 2008 05 13 Thread on gapless playback on Zune HD 2010 02 25 Retrieved 2010 05 04 Rio Karma 20Gb MP3 Player 24 April 2004 Sony NWZ F806 Specification Guide Page 1 of 4 Ittousai ビクターAlneo にギャップレス再生 AAC対応の新モデル Engadget Japanese Retrieved 7 December 2017 新製品レビュー av watch impress co jp Retrieved 7 December 2017 Thread on Gapless Playback on Amarok Mailing List 2006 09 06 Retrieved 2007 01 19 Implemented Gapless Playback 23 December 2018 Notes edit Despite this there are encoders which store the amount of padding introduced in metadata to allow gapless playback This can only be used if the playback software is able to interpret the metadata information a b c Vorbis and Speex feature gapless support through the Ogg layer The reference implementation of Speex did not initially ship with gapless metadata support External links editMP3 players Buyer Beware a description of gapless playback in digital audio players Retrieved from https en wikipedia org w index php title Gapless playback amp oldid 1177054181, wikipedia, wiki, book, books, library,

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