ATRAC
Encyclopedia
Adaptive Transform Acoustic Coding (ATRAC) is a family of proprietary audio compression algorithms
developed by Sony
. MiniDisc
was the first commercial product to incorporate ATRAC in 1992. ATRAC allowed a relatively small disc like MiniDisc to have the same running time as CD while storing audio information with minimal loss in perceptible quality. Improvements to the codec in the form of ATRAC3, ATRAC3plus, and ATRAC Advanced Lossless followed in 1999, 2002, and 2006 respectively.
Other MiniDisc manufacturers such as Sharp
and Panasonic
also implemented their own versions of the ATRAC codec.
development engineers within Sony in order to deliver on a tangible product that could encode at high speeds and with minimal power consumption. This is in contrast to other codecs developed on computers with no regard for the constraints of portable hardware. This is reflected in the design of the ATRAC codecs, which tend to emphasize processing smaller numbers of samples at a time to save memory at the cost compression efficiency and additional multiplies. These trade-offs are entirely logical on DSP systems, where memory is often at a premium compared to multiplier performance.
Sony Walkman
s offer better battery life when playing ATRAC files as compared to MP3
files. However, as Sony only pushed ATRAC compatibility in Sony Ericsson
Walkman series phones in the Japanese market, it is not supported in GSM/UMTS market phones. Sony's Xplod series of car audio CD players support ATRAC CDs. Minidiscs with ATRAC format songs have, in the past, been supported on Eclipse brand car stereos.
Two stacked quadrature mirror filter
s split the signal into 3 parts:
Full stereo
(i.e., independent channel) encoding with a data rate is 292 kbit/s.
Quality is generally transparent
for many people (meaning that it is not possible to tell an ATRAC encoding from the source). This is most possible when using the latest algorithm, Type-S, or Type-R (Type-S only improves LP modes). Like most other audio compression codecs, some signals will "trip" the codec and cause artifacts
, though these are not usually severe enough to be obvious.
High-frequency
lowpass depends on the complexity of the material; some encodings have content clear up to 22.05 kHz.
ATRAC1 can also be used in mono
(one channel) mode, doubling recording time.
FFmpeg
has an implementation of an ATRAC1 decoder.
-MDCT
encoder, but with several differences.
In ATRAC3, Three stacked QMF split the signal into 4 parts:
The four subbands
are then MDCT encoded using a fixed length transform. Unlike nearly all modern formats, the transform length cannot be varied to optimize coding transients. Instead, a simpler transient encoding technique called gain control is used, in which the gain of different subbands is varied during a transient prior to MDCT and then restored during decoding after the inverse MDCT to try to smooth over transients. Additionally, prior to quantization, tonal components are subtracted from the signal and independently quantized. During decoding, they are separately reconstructed and added back to reform the original MDCT coefficients.
Sony claims the major advantage of ATRAC3 is its coding efficiency, which was tuned for portable DSP which provides less computing power and battery life. However, as ATRAC is a hybrid subband
-MDCT
codec that is algorithmically very similar to MP3
, any advantage is probably exaggerated. Furthermore, compared to newer formats such as Windows Media Audio
which use a simple MDCT rather than a hybrid, ATRAC3 must perform an additional and computationally expensive inverse-QMF
, although the hybrid system does significantly reduce memory usage, which was likely a factor given the limited memory available when ATRAC was originally developed.
LP2 Mode
This uses a 132 kbit/s data rate, the quality of which is advertised to be similar to that of MP3
encoded at a similar bit rate.
However, in an independent double-blind
test (2004/05) without format encoding parameters reference against Ogg Vorbis
, AAC
, and LAME
VBR MP3
, ATRAC3 came last. Unfortunately, due to lack of transparency in ATRAC encoder versioning, it is not known if the ATRAC3 encoder tested was optimal, and subsequent investigation was inconclusive. It is possible that newer ATRAC3 encoders offer better performance.
LP4 Mode
This reduces the data rate to 66 kbit/s (half that of LP2), partly by using joint stereo coding and a lowpass filter
around 13.5 kHz. It allows 324 minutes to be recorded on an 80 minute MiniDisc, with the same padding required as LP2.
FFmpeg
has an implementation of an ATRAC3 decoder, which was converted to fixed precision and implemented in the Rockbox
series of firmwares for ARM
, Coldfire and MIPS
processors. RealAudio8 is an implementation of ATRAC3.
The PlayStation3 game Race Driver: Grid
uses 224 simultaneous streams of ATRAC3 compressed audio, with between one and eight channels per stream at sample rates between 24 and 48 kHz, each filtered using 512 frequency bands of adaptive equalisation, routed via six reverb units running on the same SPU co-processor (one of eight on the PS3's Cell chip), alongside 7.1 channel hybrid third-order Ambisonic mixing.
This codec
is used in Sony Hi-MD
Walkman
devices (e.g., "Hi-LP and Hi-SP"), Network Walkman
players, Memory Stick
players, VAIO
Pocket, PS3 and PSP
console, and ATRAC CD players
. It is a hybrid subband/MDCT
codec based on a 16 channel QMF
followed by a 128 point MDCT
. Prior to MDCT coding, Generalized Harmonic Analysis (GHA) is used to extract tonal components, an improved version of the process used in ATRAC3. As in previous ATRAC versions, gain control is used to control preecho rather than variable sized transforms, although different MDCT windows are apparently possible.
In the recently released SonicStage
version 3.2 and 3.3 some more bitrates have been introduced, the available bitrates are: 48, 64, 96, 128, 160, 192, 256, 320 and 352 kbit/s. The newer bitrates are not always compatible with all older hardware decoders, however, some of the older hardware has been found to be compatible with certain newer ATRAC3plus bitrates.
MiniDiscs recorded in this format are incompatible with older players.
In a test conducted by an independent firm, but financed by Sony, it was concluded that ATRAC3plus at 64 kbit/s is equal in subjective sound quality to an obsolete MP3 encoder at 128 kbit/s. Performance against modern high quality MP3 encoders was not evaluated.
ATRAC Advanced Lossless provides "scalable" compression; it records a lossy ATRAC3 or ATRAC3plus stream, and supplements it, in the same file, with a stream of correction information that allows the original signal to be reproduced, if desired. A player/decoder can extract and use just the ATRAC3 or ATRAC3plus data, or it can combine that with the correction stream to perfectly reproduce the original audio information. This allows the file to be decoded as either lossless or lossy. It is implemented in such a way that allows the file size to be smaller than uncompressed or compressed versions of the same file. Benefits of scalable compression include providing backward compatibility and faster transfer speed between portable audio devices and PC.
ATRAC Advanced Lossless is widely supported in older Walkman
players and SonicStage version 4 or later. Sonic Stage 4 allows download of ATRAC Advanced Lossless to Minidisc Players, PlayStation Portable
, and Playstation 3
. Recent Walkman players do not support ATRAC Advanced Lossless/ATRAC. Sony has all but dropped the ATRAC related codecs in the USA and Europe and their SonicStage powered 'Connect' Music Service (Sony's equivalent of iTunes) on 31 March 2008. However, it is being continued in Japan and various other countries.
, DTS-HD Master Audio
, and Ogg Vorbis bitrate peeling
.
WavPack
hybrid mode and OptimFROG
DualStream are in the same category, but store the correction stream in a separate file.
News portal, discussion forums and downloads related to ATRAC.
Audio codec
All codecs are devices or computer programs capable of coding or decoding a digital data stream or signal.The term audio codec has two meanings depending on the context:...
developed by Sony
Sony
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....
. MiniDisc
MiniDisc
The disc is permanently housed in a cartridge with a sliding door, similar to the casing of a 3.5" floppy disk. This shutter is opened automatically by a mechanism upon insertion. The audio discs can either be recordable or premastered. Recordable MiniDiscs use a magneto-optical system to record...
was the first commercial product to incorporate ATRAC in 1992. ATRAC allowed a relatively small disc like MiniDisc to have the same running time as CD while storing audio information with minimal loss in perceptible quality. Improvements to the codec in the form of ATRAC3, ATRAC3plus, and ATRAC Advanced Lossless followed in 1999, 2002, and 2006 respectively.
Other MiniDisc manufacturers such as Sharp
Sharp Corporation
is a Japanese multinational corporation that designs and manufactures electronic products. Headquartered in Abeno-ku, Osaka, Japan, Sharp employs more than 55,580 people worldwide as of June 2011. The company was founded in September 1912 and takes its name from one of its founder's first...
and Panasonic
Panasonic
Panasonic is an international brand name for Japanese electric products manufacturer Panasonic Corporation, which was formerly known as Matsushita Electric Industrial Co., Ltd...
also implemented their own versions of the ATRAC codec.
General bitrate quality
ATRAC's original 292 kbit/s bitrate was designed to be close to CD quality acoustically. This is the bitrate used on original MiniDiscs. Years later ATRAC was improved and is generally considered better than earlier versions at similar bitrates. For purposes of comparison, CDs are encoded at 1411.2 kbit/s, and lossless encoders can encode most CDs below 1000 kbit/s, with significant bitrate reduction for easier-to-encode content such as voice.Performance
According to ATRAC engineers, ATRAC algorithms were developed in close cooperation with LSILSI Corporation
LSI Corporation is an electronics company based in Milpitas, California that designs semiconductors and software that accelerate storage and networking in datacenters and mobile networks.-History:...
development engineers within Sony in order to deliver on a tangible product that could encode at high speeds and with minimal power consumption. This is in contrast to other codecs developed on computers with no regard for the constraints of portable hardware. This is reflected in the design of the ATRAC codecs, which tend to emphasize processing smaller numbers of samples at a time to save memory at the cost compression efficiency and additional multiplies. These trade-offs are entirely logical on DSP systems, where memory is often at a premium compared to multiplier performance.
Sony Walkman
Walkman
Walkman is a Sony brand tradename originally used for portable audio cassette, and now used to market Sony's portable audio and video players as well as a line of Sony Ericsson mobile phones...
s offer better battery life when playing ATRAC files as compared to MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...
files. However, as Sony only pushed ATRAC compatibility in Sony Ericsson
Sony Ericsson
Sony Ericsson Mobile Communications AB is a joint venture established on October 1, 2001 by the Japanese consumer electronics company Sony Corporation and the Swedish telecommunications company Ericsson to manufacture mobile phones....
Walkman series phones in the Japanese market, it is not supported in GSM/UMTS market phones. Sony's Xplod series of car audio CD players support ATRAC CDs. Minidiscs with ATRAC format songs have, in the past, been supported on Eclipse brand car stereos.
ATRAC1
ATRAC1 was first used in Sony's own theater format SDDS system in the 1990s, and in this context is a direct competitor to Dolby Digital (AC3) and DTS. SDDS uses ATRAC1 with 8 channel encoding, and with a total encoding rate over all the channels of 1168 kbit/s.Two stacked quadrature mirror filter
Quadrature mirror filter
In digital signal processing, a quadrature mirror filter is a filter most commonly used to implement a filter bank that splits an input signal into two bands...
s split the signal into 3 parts:
- 0 to 5.5125 kHz
- 5.5125 to 11.025 kHz
- 11.025 to 22.05 kHz
Full stereo
Stereophonic sound
The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
(i.e., independent channel) encoding with a data rate is 292 kbit/s.
Quality is generally transparent
Transparency (data compression)
In data compression or psychoacoustics, transparency is the ideal result of lossy data compression. If a lossy compressed result is perceptually indistinguishable from the uncompressed input, then the compression can be declared to be transparent...
for many people (meaning that it is not possible to tell an ATRAC encoding from the source). This is most possible when using the latest algorithm, Type-S, or Type-R (Type-S only improves LP modes). Like most other audio compression codecs, some signals will "trip" the codec and cause artifacts
Compression artifact
A compression artifact is a noticeable distortion of media caused by the application of lossy data compression....
, though these are not usually severe enough to be obvious.
High-frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
lowpass depends on the complexity of the material; some encodings have content clear up to 22.05 kHz.
ATRAC1 can also be used in mono
Monaural
Monaural or monophonic sound reproduction is single-channel. Typically there is only one microphone, one loudspeaker, or channels are fed from a common signal path...
(one channel) mode, doubling recording time.
FFmpeg
FFmpeg
FFmpeg is a free software project that produces libraries and programs for handling multimedia data. The most notable parts of FFmpeg are libavcodec, an audio/video codec library used by several other projects, libavformat, an audio/video container mux and demux library, and the ffmpeg command line...
has an implementation of an ATRAC1 decoder.
ATRAC3 (LP2 and LP4 Modes)
Like ATRAC1 and MP3, ATRAC3 is also a hybrid subbandSub-band coding
Sub-band coding is any form of transform coding that breaks a signal into a number of different frequency bands and encodes each one independently. This decomposition is often the first step in data compression for audio and video signals....
-MDCT
Modified discrete cosine transform
The modified discrete cosine transform is a Fourier-related transform based on the type-IV discrete cosine transform , with the additional property of being lapped: it is designed to be performed on consecutive blocks of a larger dataset,...
encoder, but with several differences.
In ATRAC3, Three stacked QMF split the signal into 4 parts:
- 0 to 2.75625 kHz (DC to f/16)
- 2.75625 to 5.5125 kHz (f/16 to f/8)
- 5.5125 to 11.025 kHz (f/8 to f/4)
- 11.025 to 22.05 kHz (f/4 to f/2)
The four subbands
Sub-band coding
Sub-band coding is any form of transform coding that breaks a signal into a number of different frequency bands and encodes each one independently. This decomposition is often the first step in data compression for audio and video signals....
are then MDCT encoded using a fixed length transform. Unlike nearly all modern formats, the transform length cannot be varied to optimize coding transients. Instead, a simpler transient encoding technique called gain control is used, in which the gain of different subbands is varied during a transient prior to MDCT and then restored during decoding after the inverse MDCT to try to smooth over transients. Additionally, prior to quantization, tonal components are subtracted from the signal and independently quantized. During decoding, they are separately reconstructed and added back to reform the original MDCT coefficients.
Sony claims the major advantage of ATRAC3 is its coding efficiency, which was tuned for portable DSP which provides less computing power and battery life. However, as ATRAC is a hybrid subband
Sub-band coding
Sub-band coding is any form of transform coding that breaks a signal into a number of different frequency bands and encodes each one independently. This decomposition is often the first step in data compression for audio and video signals....
-MDCT
Modified discrete cosine transform
The modified discrete cosine transform is a Fourier-related transform based on the type-IV discrete cosine transform , with the additional property of being lapped: it is designed to be performed on consecutive blocks of a larger dataset,...
codec that is algorithmically very similar to MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...
, any advantage is probably exaggerated. Furthermore, compared to newer formats such as Windows Media Audio
Windows Media Audio
Windows Media Audio is an audio data compression technology developed by Microsoft. The name can be used to refer to its audio file format or its audio codecs. It is a proprietary technology that forms part of the Windows Media framework. WMA consists of four distinct codecs...
which use a simple MDCT rather than a hybrid, ATRAC3 must perform an additional and computationally expensive inverse-QMF
Quadrature mirror filter
In digital signal processing, a quadrature mirror filter is a filter most commonly used to implement a filter bank that splits an input signal into two bands...
, although the hybrid system does significantly reduce memory usage, which was likely a factor given the limited memory available when ATRAC was originally developed.
LP2 Mode
This uses a 132 kbit/s data rate, the quality of which is advertised to be similar to that of MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...
encoded at a similar bit rate.
However, in an independent double-blind
Double-blind
A blind or blinded experiment is a scientific experiment where some of the people involved are prevented from knowing certain information that might lead to conscious or subconscious bias on their part, invalidating the results....
test (2004/05) without format encoding parameters reference against Ogg Vorbis
Vorbis
Vorbis is a free software / open source project headed by the Xiph.Org Foundation . The project produces an audio format specification and software implementation for lossy audio compression...
, AAC
Advanced Audio Coding
Advanced Audio Coding is a standardized, lossy compression and encoding scheme for digital audio. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at similar bit rates....
, and LAME
LAME
LAME is a free software codec used to encode/compress audio into the lossy MP3 file format.-History:The name LAME is a recursive acronym for "LAME Ain't an MP3 Encoder". Around mid-1998, Mike Cheng created LAME 1.0 as a set of modifications against the "8Hz-MP3" encoder source code...
VBR MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...
, ATRAC3 came last. Unfortunately, due to lack of transparency in ATRAC encoder versioning, it is not known if the ATRAC3 encoder tested was optimal, and subsequent investigation was inconclusive. It is possible that newer ATRAC3 encoders offer better performance.
LP4 Mode
This reduces the data rate to 66 kbit/s (half that of LP2), partly by using joint stereo coding and a lowpass filter
Low-pass filter
A low-pass filter is an electronic filter that passes low-frequency signals but attenuates signals with frequencies higher than the cutoff frequency. The actual amount of attenuation for each frequency varies from filter to filter. It is sometimes called a high-cut filter, or treble cut filter...
around 13.5 kHz. It allows 324 minutes to be recorded on an 80 minute MiniDisc, with the same padding required as LP2.
FFmpeg
FFmpeg
FFmpeg is a free software project that produces libraries and programs for handling multimedia data. The most notable parts of FFmpeg are libavcodec, an audio/video codec library used by several other projects, libavformat, an audio/video container mux and demux library, and the ffmpeg command line...
has an implementation of an ATRAC3 decoder, which was converted to fixed precision and implemented in the Rockbox
Rockbox
Rockbox is a replacement for the standard firmware in various forms of digital audio players . It offers an alternative to the player's operating system, in many cases without removing the original firmware, which provides a plug-in architecture for adding various enhancements and functions...
series of firmwares for ARM
ARM architecture
ARM is a 32-bit reduced instruction set computer instruction set architecture developed by ARM Holdings. It was named the Advanced RISC Machine, and before that, the Acorn RISC Machine. The ARM architecture is the most widely used 32-bit ISA in numbers produced...
, Coldfire and MIPS
MIPS architecture
MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
processors. RealAudio8 is an implementation of ATRAC3.
The PlayStation3 game Race Driver: Grid
Race Driver: GRID
Race Driver: Grid is the most recent addition to the TOCA Touring Car series, which is published and developed by Codemasters...
uses 224 simultaneous streams of ATRAC3 compressed audio, with between one and eight channels per stream at sample rates between 24 and 48 kHz, each filtered using 512 frequency bands of adaptive equalisation, routed via six reverb units running on the same SPU co-processor (one of eight on the PS3's Cell chip), alongside 7.1 channel hybrid third-order Ambisonic mixing.
ATRAC3plus
Codec
A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "compressor-decompressor" or, more commonly, "coder-decoder"...
is used in Sony Hi-MD
Hi-MD
In January 2004, Sony announced the Hi-MD media storage format as a further development of the MiniDisc format. With its release in later 2004 came the ability to use newly-developed, high-capacity 1 gigabyte Hi-MD discs, sporting the same dimensions as regular MiniDiscs.- Main features :* The...
Walkman
Walkman
Walkman is a Sony brand tradename originally used for portable audio cassette, and now used to market Sony's portable audio and video players as well as a line of Sony Ericsson mobile phones...
devices (e.g., "Hi-LP and Hi-SP"), Network Walkman
Walkman
Walkman is a Sony brand tradename originally used for portable audio cassette, and now used to market Sony's portable audio and video players as well as a line of Sony Ericsson mobile phones...
players, Memory Stick
Memory Stick
Memory Stick is a removable flash memory card format, launched by Sony in October 1998, and is also used in general to describe the whole family of Memory Sticks...
players, VAIO
VAIO
VAIO is a sub-brand used for many of Sony's computer products. Originally an acronym of Video Audio Integrated Operation, this was amended to Visual Audio Intelligent Organizer in 2008 to celebrate the brand's 10th anniversary...
Pocket, PS3 and PSP
PlayStation Portable
The is a handheld game console manufactured and marketed by Sony Corporation Development of the console was announced during E3 2003, and it was unveiled on , 2004, at a Sony press conference before E3 2004...
console, and ATRAC CD players
Compact disc player
A Compact Disc player , or CD player, is an electronic device that plays audio Compact Discs. CD players are often a part of home stereo systems, car audio systems, and personal computers. They are also manufactured as portable devices...
. It is a hybrid subband/MDCT
Modified discrete cosine transform
The modified discrete cosine transform is a Fourier-related transform based on the type-IV discrete cosine transform , with the additional property of being lapped: it is designed to be performed on consecutive blocks of a larger dataset,...
codec based on a 16 channel QMF
Quadrature mirror filter
In digital signal processing, a quadrature mirror filter is a filter most commonly used to implement a filter bank that splits an input signal into two bands...
followed by a 128 point MDCT
Modified discrete cosine transform
The modified discrete cosine transform is a Fourier-related transform based on the type-IV discrete cosine transform , with the additional property of being lapped: it is designed to be performed on consecutive blocks of a larger dataset,...
. Prior to MDCT coding, Generalized Harmonic Analysis (GHA) is used to extract tonal components, an improved version of the process used in ATRAC3. As in previous ATRAC versions, gain control is used to control preecho rather than variable sized transforms, although different MDCT windows are apparently possible.
In the recently released SonicStage
SonicStage
SonicStage is the name for Sony software that is used for managing portable devices when they are plugged into a computer running Microsoft Windows. It comprises a music player and library manager, similar to iTunes, Windows Media Player and RealPlayer. It is used to manage the library of ATRAC...
version 3.2 and 3.3 some more bitrates have been introduced, the available bitrates are: 48, 64, 96, 128, 160, 192, 256, 320 and 352 kbit/s. The newer bitrates are not always compatible with all older hardware decoders, however, some of the older hardware has been found to be compatible with certain newer ATRAC3plus bitrates.
MiniDiscs recorded in this format are incompatible with older players.
In a test conducted by an independent firm, but financed by Sony, it was concluded that ATRAC3plus at 64 kbit/s is equal in subjective sound quality to an obsolete MP3 encoder at 128 kbit/s. Performance against modern high quality MP3 encoders was not evaluated.
ATRAC Advanced Lossless
ATRAC Advanced Lossless (AAL) is the latest update to the codec family. It can provide compression for a CD music source at approximately 30–80% of the original size without any quality loss.ATRAC Advanced Lossless provides "scalable" compression; it records a lossy ATRAC3 or ATRAC3plus stream, and supplements it, in the same file, with a stream of correction information that allows the original signal to be reproduced, if desired. A player/decoder can extract and use just the ATRAC3 or ATRAC3plus data, or it can combine that with the correction stream to perfectly reproduce the original audio information. This allows the file to be decoded as either lossless or lossy. It is implemented in such a way that allows the file size to be smaller than uncompressed or compressed versions of the same file. Benefits of scalable compression include providing backward compatibility and faster transfer speed between portable audio devices and PC.
ATRAC Advanced Lossless is widely supported in older Walkman
Walkman
Walkman is a Sony brand tradename originally used for portable audio cassette, and now used to market Sony's portable audio and video players as well as a line of Sony Ericsson mobile phones...
players and SonicStage version 4 or later. Sonic Stage 4 allows download of ATRAC Advanced Lossless to Minidisc Players, PlayStation Portable
PlayStation Portable
The is a handheld game console manufactured and marketed by Sony Corporation Development of the console was announced during E3 2003, and it was unveiled on , 2004, at a Sony press conference before E3 2004...
, and Playstation 3
PlayStation 3
The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...
. Recent Walkman players do not support ATRAC Advanced Lossless/ATRAC. Sony has all but dropped the ATRAC related codecs in the USA and Europe and their SonicStage powered 'Connect' Music Service (Sony's equivalent of iTunes) on 31 March 2008. However, it is being continued in Japan and various other countries.
Comparable technology
AAL's use of a "core" (lossy) and "residual" (correction) stream is similar to the idea behind MPEG-4 SLSMPEG-4 SLS
MPEG-4 SLS, or MPEG-4 Scalable to Lossless as per ISO/IEC 14496-3:2005/Amd 3:2006 , is an extension to the MPEG-4 Part 3 standard to allow lossless audio compression scalable to lossy MPEG-4 General Audio coding methods...
, DTS-HD Master Audio
DTS-HD Master Audio
DTS-HD Master Audio is a lossless audio codec created by Digital Theater System. It was previously known as DTS++. It is an extension of DTS which, when played back on devices which do not support the Master Audio or High Resolution extension, degrades to a "core" track which is lossy. DTS-HD...
, and Ogg Vorbis bitrate peeling
Bitrate peeling
Bitrate Peeling is a technique used in Ogg Vorbis audio encoded streams, wherein a stream can be encoded at one bitrate but can be served at that or any lower bitrate....
.
WavPack
WavPack
WavPack is a free, open source lossless audio compression format developed by David Bryant.-Features:WavPack compression can compress 8-, 16-, 24-, and 32-bit fixed-point, and 32-bit floating point audio files in the .WAV file format. It also supports surround sound streams and high frequency...
hybrid mode and OptimFROG
OptimFROG
OptimFROG is a proprietary lossless audio data compression codec developed by Florin Ghido. OptimFROG is optimized for very high compression ratios, even for the price of slower encoding and decoding.-OptimFROG DualStream:...
DualStream are in the same category, but store the correction stream in a separate file.
See also
- Lossy data compressionLossy data compressionIn information technology, "lossy" compression is a data encoding method that compresses data by discarding some of it. The procedure aims to minimize the amount of data that need to be held, handled, and/or transmitted by a computer...
- OpenMGOpenMGOpenMG is a SDMI-compliant digital rights management system by Sony. It is designed for audio files in ATRAC3 format. The compliant software, eg. Sony SonicStage, is usually capable of transcoding MP3 and wav files to OpenMG/ATRAC3...
- SonicStageSonicStageSonicStage is the name for Sony software that is used for managing portable devices when they are plugged into a computer running Microsoft Windows. It comprises a music player and library manager, similar to iTunes, Windows Media Player and RealPlayer. It is used to manage the library of ATRAC...
- WalkmanWalkmanWalkman is a Sony brand tradename originally used for portable audio cassette, and now used to market Sony's portable audio and video players as well as a line of Sony Ericsson mobile phones...
- Connect Music Store
External links
- ATRACLife.com - This domain is now parked, forum content only available from google cache.
News portal, discussion forums and downloads related to ATRAC.
- Sony.net, ATRAC technology page.