Free Lossless Audio Codec
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| Free Lossless Audio Codec | |
|---|---|
| File name extension | .flac |
| Internet media type | audio/x-flac[1] |
| Type of format | Audio |
| Free Lossless Audio Codec | |
|---|---|
| Developed by | Xiph.Org Foundation |
| Latest release | 1.2.1 / September 17, 2007 |
| OS | Cross-platform |
| Genre | Audio codec, Audio file format |
| License | GPL BSD (Xiph.Org parts) |
| Website | flac.sourceforge.net |
Free Lossless Audio Codec (FLAC) is a file format for audio data compression. Being a lossless compression format, FLAC does not remove information from the audio stream, as lossy compression formats such as MP3, AAC, and Vorbis do.
Like other methods of compression, FLAC's main advantage is the reduction of bandwidth or storage requirements, but without sacrificing the integrity of the audio source. For example, a digital recording (such as a CD) encoded to FLAC can be decompressed into an identical copy of the audio data. Audio sources encoded to FLAC are typically reduced in size 40 to 50 percent (47% according to their own comparison).[2]
FLAC is suitable for everyday playback and audio archival, with support for tagging, cover art and fast seeking. FLAC's free and open source royalty-free nature makes it well-supported by many software applications, however, FLAC playback support in portable audio devices and dedicated audio systems is limited at this time.[3] Josh Coalson is the primary author of FLAC.
On January 29, 2003, Xiphophorus (now called the Xiph.Org Foundation) announced the incorporation of FLAC under their banner, alongside Vorbis, Theora, Speex, and others.
Contents |
[edit] The project
The FLAC project consists of:
- The stream format
- A simple container format for the stream, also called FLAC (or Native FLAC)
- libFLAC, a library of reference encoders and decoders, and a metadata interface
- libFLAC++, an object wrapper around libFLAC
- flac, a command-line wrapper around libFLAC to encode and decode FLAC streams
- metaflac, a command-line metadata editor for .flac files and for applying Replay Gain
- Input plugins for various music players (Winamp, XMMS, foobar2000, musikCube, and many more)
- With Xiph.org incorporation, the Ogg container format, suitable for streaming (also called Ogg FLAC)
"Free" means that the specification of the stream format can be implemented by anyone without prior permission (Xiph.org reserves the right to set the FLAC specification and certify compliance), and that neither the FLAC format nor any of the implemented encoding/decoding methods are covered by any patent. It also means that the reference implementation is free software. The sources for libFLAC and libFLAC++ are available under Xiph.org's BSD license, and the sources for flac, metaflac, and the plugins are available under the GPL.
In its stated goals, the FLAC project encourages its developers not to implement copy prevention features of any kind.[3]
[edit] Comparisons
FLAC is specifically designed for efficient packing of audio data, unlike general lossless algorithms such as ZIP and gzip. While ZIP may compress a CD-quality audio file by 10 - 20%, FLAC achieves compression rates of 30 - 50% for most music, with significantly greater compression for voice recordings.
Lossy codecs can achieve ratios of 80% or more by discarding data from the original stream. FLAC uses linear prediction to convert the audio samples to a series of small, uncorrelated numbers (known as the residual), which are stored efficiently using Golomb-Rice coding. It also uses run-length encoding for blocks of identical samples, such as silent passages. The technical strengths of FLAC compared to other lossless codecs lie in its ability to be streamed and in a fast decode time, which is independent of compression level.
As with any lossless scheme, FLAC is also a popular archive format for owners of CDs and other media who wish to preserve their audio collections. If the original media is lost, damaged, or worn out, a FLAC copy of the audio tracks ensures that an exact duplicate of the original data can be recovered at any time. An exact restoration from a lossy archive (e.g., MP3) of the same data is impossible. A CUE file can optionally be created when ripping a CD. If a CD is read and ripped perfectly to FLAC files, the CUE file allows later burning of an audio CD that is identical in audio data to the original CD, including track order, pregaps, and CD-Text. However, additional data present on some audio CDs such as lyrics and CD+G graphics are beyond the scope of a CUE file and most ripping software, so that data will not be archived.
The European Broadcasting Union (EBU) has adopted the FLAC format over its Euroradio network for the distribution of high quality audio.
The Hydrogenaudio Wiki features a comparison of lossless codecs, including FLAC.
[edit] Technical details
FLAC supports only fixed-point samples, not floating-point. It can handle any PCM bit resolution from 4 to 32 bits per sample, any sampling rate from 1 Hz to 1,048,570 Hz in 1 Hz increments, and any number of channels from 1 to 8. Channels can be grouped in cases like stereo and 5.1 channel surround to take advantage of interchannel correlations to increase compression. FLAC uses CRC checksums for identifying corrupted frames when used in a streaming protocol, and also has a complete MD5 hash of the raw PCM audio stored in its STREAMINFO metadata header.
FLAC allows for Rice parameter between 0-16, and up to 8 channels of audio and a wide range of sampling rates up to 192 kHz, in various bits-per-sample width. FLAC also supports Replay Gain.
FLAC is implemented as the libFLAC core encoder & decoder library with the main distributable program flac being the reference program utilizing the libFLAC API. This codec API is also available in C++ as libFLAC++.
The reference implementation of FLAC compiles on many platforms, including most Unix (such as Solaris and Mac OS X) and Unix-like (including Linux and BSD), Windows, BeOS, and OS/2 operating systems. There are build systems for autoconf/automake, MSVC, Watcom C, and Xcode.
For tagging, FLAC uses the same system as Vorbis comments.[4]
[edit] API Organization
libFLAC API is organized into streams, seekable streams, and files (listed in the order of increasing abstraction from the base FLAC bitstream). Most FLAC applications will generally restrict themselves to encoding/decoding using libFLAC at the file level interface.
[edit] Software support
[edit] Encoding
- Cross-Platform
- FFmpeg
- Flake
- Audacity 1.3.3 Beta Native FLAC support now included
- VLC media player 0.8.6a
- Juce
- aTunes
- Windows
- SMPlayer
- KMPlayer
- Ease Audio Converter
- Easy Media Creator
- Easy CD-DA Extractor
- Exact Audio Copy
- Nero Burning ROM with optional external filter plug-in
- dBpoweramp Music Converter with official codec
- MediaMonkey
- Winamp native FLAC support now included
- JetAudio
- foobar2000 with official external encoder
- MP3 Stream Editor with official external encoder
- Omni Encoder with official external encoder
- Burrrn
- Flac Frontend
- Total Audio Converter
- Vegas Pro 8[1]
- Yahoo! Music Jukebox
- Roxio Easy Media Creator
- Mac OS X
[edit] Decoding
- Cross-Platform
- FFmpeg
- aTunes
- Audacity 1.3.3 Beta
- JUCE (cross-platform C++ toolkit that has embedded FLAC support)
- Linn Digital Stream Players (see below for range of devices)
- MPlayer
- Songbird
- Squeezebox
- The Core Pocket Media Player with flac plugin
- VLC media player
- Total Audio Converter
- Mac OS X
- FLAC Importer, Quicktime Component
- Cog
- Play
- xACT, not to be confused with Microsoft's XACT audio programming library
- MacFLAC, decodes to file, no player functionality
- FLACer
- Windows
- AIMP
- ALTools-based ALSong
- Ease Audio Converter
- foobar2000
- iTunes after installing codec from Xiph (Ogg FLAC only)
- Cirlinca DVD-AUDIO Solo can import FLAC to burn DVD-Audio discs
- JetAudio
- KSP Sound Player plugin included with normal install
- MediaMonkey
- MP3 Stream Editor plugin included with normal install
- Cockos REAPER Multitrack Recorder and Editor
- Renoise supports import and export from version 1.8
- Quintessential Player with flac plugin
- The KMPlayer
- TRAKTOR 3
- TRAKTOR Scratch
- TVersity, using ffdshow to transcode stream to WAV
- Vegas Pro 8[2]
- Winamp
- Windows Media Player and Media Player Classic with third-party plugin
- XMPlay
- FairStars Audio Converter
- Yahoo! Music Jukebox
- Linux
[edit] Ripping
- Cross-Platform
- Windows
- BonkEnc using the FLAC.dll API
- CD to MP3 Maker
- CDex using the external encoder option (now lists "flac.dll" as an encoder option if flac is installed)
- DBpoweramp
- Easy CD-DA Extractor
- Exact Audio Copy using the external encoder
- foobar2000 using the Converter plugin and the external encoder
- MediaMonkey
- MP3 Stream Editor using the official external encoder (single mode/album mode/full cover picture support)
- JetAudio
- Winamp
- PlexTools
- Yahoo! Music Jukebox
- Mac OS X
- Max (Mac OS 10.4 or higher)
- Linux
- ABCDE
- Banshee (music player)
- Cdda2wav
- Cdparanoia
- Mencoder
- crip
- RipIt (Command line tool)
- GNOME
- Grip
- RipOff
- Sound Juicer
- KDE
[edit] Hardware support
[edit] Native
- Escient[5]
- iAudio (Cowon) - A2, A3, 6, 7, F2, M3, M5, X5, U3, U5[6], D2, native support with newer firmwares.
- Olive (Symphony, Musica, Opus)[7]
- PhatBox Hard Drive based in car Digital Media Player from PhatNoise
- Rio Karma
- Squeezebox and Transporter network music players from Slim Devices. Current products decode natively. Old v1 units transcode to PCM on the server.
- Sonos
- Meizu M6 Mini Player, M3 Music Card
- Pixel Magic Systems' HD Mediabox (with firmware 1.3.4 or higher)
- Embedded Waveplayer- Module with FLAC level 0-2 support, MIDI and serial interface
- Teclast T29, T39, C260, C280, C290
- Trekstor Vibez
- Denon AVR-4308 & AVR-3808 AV Receiver[8]
- T+A Music Player[9]
- Linn Klimax DS (Digital Stream) digital music player
- Linn Akurate DS digital music player
- Linn Majik DS digital music player (available later in 2008)
- Linn Sneaky Music DS digital music player
- iriver E100[10]
[edit] Third-party
- Microsoft Xbox when running the third party Xbox Media Center
- iPod - 1st through 5.5th generation, iPod mini and 1st generation iPod nano (not the shuffle, 2nd/3rd gen nano, classic or touch), using third party Rockbox firmware
- Nearly all Rockbox-compatible DAPs, including the iriver and Gigabeat (Toshiba) range of devices, plus the aforementioned iPods
- Any UPnP A/V / DLNA Device - - e.g. Netgear EVA700, Netgear MP101, Roku Soundbridge or Xbox 360 (when transcoded data is streamed from applications such as TVersity, which uses ffdshow)
- Sound Devices 7-Series Professional Audio Recorders with "badger" firmware update (v.2.24)[11]
[edit] See also
[edit] References
- ^ Registration being sought as audio/flac
- ^ FLAC - comparison. Retrieved on 2008-01-27.
- ^ a b FLAC Website
- ^ FLAC - faq. Retrieved on 2008-01-27.
- ^ Supported Digital Music Formats & Tagging Requirements (PDF) p. 2. Escient. Retrieved on 2008-01-27.
- ^ Korean firmware V2.13
- ^ Olive. Retrieved on 2008-01-27.
- ^ DENON UK. Retrieved on 2008-01-27.
- ^ T+A E-Series Music-Player. Retrieved on 2008-01-27.
- ^ iRiver E100.
- ^ Data Compression and Reduction Options for 7-Series Recorders. Retrieved on 2008-01-27.
[edit] External links
- Official Website
- Comparison of lossless formats by Hans Heiden (somewhat outdated)
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