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MPEG-4 Part 3

January 01, 1970

MPEG-4 Part 3 or MPEG-4 Audio (formally ISO/IEC 14496-3) is the third part of the ISO/IEC MPEG-4 international standard developed by Moving Picture Experts Group.[1] It specifies audio coding methods. The first version of ISO/IEC 14496-3 was published in 1999.[2]

The MPEG-4 Part 3 consists of a variety of audio coding technologies – from lossy speech coding (HVXC, CELP), general audio coding (AAC, TwinVQ, BSAC), lossless audio compression (MPEG-4 SLS, Audio Lossless Coding, MPEG-4 DST), a Text-To-Speech Interface (TTSI), Structured Audio (using SAOL, SASL, MIDI) and many additional audio synthesis and coding techniques.[3][4][5][6][7][8][9][10][11]

MPEG-4 Audio does not target a single application such as real-time telephony or high-quality audio compression. It applies to every application which requires the use of advanced sound compression, synthesis, manipulation, or playback. MPEG-4 Audio is a new type of audio standard that integrates numerous different types of audio coding: natural sound and synthetic sound, low bitrate delivery and high-quality delivery, speech and music, complex soundtracks and simple ones, traditional content and interactive content.[7]

Versions edit

MPEG-4 Audio versions and editions[12]
Edition Release date Latest amendment Standard Description
First edition 1999 2001 ISO/IEC 14496-3:1999[2] also known as "MPEG-4 Audio Version 1"
2000 ISO/IEC 14496-3:1999/Amd 1:2000[13] also known as "MPEG-4 Audio Version 2", an Amendment to first edition[7][8]
Second edition 2001 2005 ISO/IEC 14496-3:2001[14]
Third edition 2005 2008 ISO/IEC 14496-3:2005[15]
Fourth edition 2009 2015 and under development[12] ISO/IEC 14496-3:2009[1][16]
Fifth edition 2019 ISO/IEC 14496-3:2019[17] Current version

Subparts edit

MPEG-4 Part 3 contains following subparts:[16]

  • Subpart 1: Main (list of Audio Object Types, Profiles, Levels, interface to ISO/IEC 14496-1, MPEG-4 Audio transport stream, etc.)
  • Subpart 2: Speech coding – HVXC (Harmonic Vector eXcitation Coding)
  • Subpart 3: Speech coding – CELP (Code Excited Linear Prediction)
  • Subpart 4: General Audio Coding (GA) (Time/Frequency Coding) – AAC, TwinVQ, BSAC
  • Subpart 5: Structured Audio (SA)
  • Subpart 6: Text to Speech Interface (TTSI)
  • Subpart 7: Parametric Audio Coding – HILN (Harmonic and Individual Line plus Noise)
  • Subpart 8: Technical description of parametric coding for high quality audio (SSC, Parametric Stereo)
  • Subpart 9: MPEG-1/MPEG-2 Audio in MPEG-4
  • Subpart 10: Technical description of lossless coding of oversampled audio (MPEG-4 DST – Direct Stream Transfer)
  • Subpart 11: Audio Lossless Coding (ALS)
  • Subpart 12: Scalable Lossless Coding (SLS)

MPEG-4 Audio Object Types edit

MPEG-4 Audio includes a system for handling a diverse group of audio formats in a uniform manner. Each format is assigned a unique Audio Object Type to represent it.[18][19] Object Type is used to distinguish between different coding methods. It directly determines the MPEG-4 tool subset required to decode a specific object. The MPEG-4 profiles are based on the object types and each profile supports a different list of object types.[19]

MPEG-4 Audio Object Types[7][9][18][20][21]
Object Type ID Audio Object Type First public release date Description
1 AAC Main 1999 contains AAC LC
2 AAC LC (Low Complexity) 1999 Used in the "AAC Profile". MPEG-4 AAC LC Audio Object Type is based on the MPEG-2 Part 7 Low Complexity profile (LC) combined with Perceptual Noise Substitution (PNS) (defined in MPEG-4 Part 3 Subpart 4).[4][22]
3 AAC SSR (Scalable Sample Rate) 1999 MPEG-4 AAC SSR Audio Object Type is based on the MPEG-2 Part 7 Scalable Sampling Rate profile (SSR) combined with Perceptual Noise Substitution (PNS) (defined in MPEG-4 Part 3 Subpart 4).[4][22]
4 AAC LTP (Long Term Prediction) 1999 contains AAC LC
5 SBR (Spectral Band Replication) 2003[23] used with AAC LC in the "High Efficiency AAC Profile" (HE-AAC v1)
6 AAC Scalable 1999
7 TwinVQ 1999 audio coding at very low bitrates
8 CELP (Code Excited Linear Prediction) 1999 speech coding
9 HVXC (Harmonic Vector eXcitation Coding) 1999 speech coding
10 (Reserved)
11 (Reserved)
12 TTSI (Text-To-Speech Interface) 1999
13 Main synthesis 1999 contains 'wavetable' sample-based synthesis[24] and Algorithmic Synthesis and Audio Effects
14 'wavetable' sample-based synthesis 1999 based on SoundFont and DownLoadable Sounds,[24] contains General MIDI
15 General MIDI 1999
16 Algorithmic Synthesis and Audio Effects 1999
17 ER AAC LC 2000 Error Resilient
18 (Reserved )
19 ER AAC LTP 2000 Error Resilient
20 ER AAC Scalable 2000 Error Resilient
21 ER TwinVQ 2000 Error Resilient
22 ER BSAC (Bit-Sliced Arithmetic Coding) 2000 It is also known as "Fine Granule Audio" or fine grain scalability tool. It is used in combination with the AAC coding tools and replaces the noiseless coding and the bitstream formatting of MPEG-4 Version 1 GA coder. Error Resilient
23 ER AAC LD (Low Delay) 2000 Error Resilient, used with CELP, ER CELP, HVXC, ER HVXC and TTSI in the "Low Delay Profile", (commonly used for real-time conversation applications)
24 ER CELP 2000 Error Resilient
25 ER HVXC 2000 Error Resilient
26 ER HILN (Harmonic and Individual Lines plus Noise) 2000 Error Resilient
27 ER Parametric 2000 Error Resilient
28 SSC (SinuSoidal Coding) 2004[25][26]
29 PS (Parametric Stereo) 2004[27] and 2006[28][29] used with AAC LC and SBR in the "HE-AAC v2 Profile". PS coding tool was defined in 2004 and Object Type defined in 2006.
30 MPEG Surround 2007[30] also known as MPEG Spatial Audio Coding (SAC), it is a type of spatial audio coding[31][32] (MPEG Surround was also defined in ISO/IEC 23003-1 in 2007[33])
31 (ESCAPE)
32 MPEG-1/2 Layer-1 2005[34]
33 MPEG-1/2 Layer-2 2005[34]
34 MPEG-1/2 Layer-3 2005[34] also known as "MP3onMP4"
35 DST (Direct Stream Transfer) 2005[35] lossless audio coding, used on Super Audio CD
36 ALS (Audio Lossless Coding) 2006[29] lossless audio coding
37 SLS (Scalable Lossless Coding) 2006[36] two-layer audio coding with lossless layer and lossy General Audio core/layer (e.g. AAC)
38 SLS non-core 2006 lossless audio coding without lossy General Audio core/layer (e.g. AAC)
39 ER AAC ELD (Enhanced Low Delay) 2008[37] Error Resilient
40 SMR (Symbolic Music Representation) Simple 2008 note: Symbolic Music Representation is also the MPEG-4 Part 23 standard (ISO/IEC 14496-23:2008)[38][39]
41 SMR Main 2008
42 USAC (Unified Speech and Audio Coding) 2012 Unified Speech and audio Coding is defined in MPEG-D Part 3 (ISO/IEC 23003-3:2012)[40]
43 SAOC (Spatial Audio Object Coding) 2010[41][42] note: Spatial Audio Object Coding is also the MPEG-D Part 2 standard (ISO/IEC 23003-2:2010)[43]
44 LD MPEG Surround 2010[44] This object type conveys Low Delay MPEG Surround Coding side information (that was defined in MPEG-D Part 2 – ISO/IEC 23003-2[43]) in the MPEG-4 Audio framework.
45 SAOC-DE 2013 Spatial Audio Object Coding Dialogue Enhancement
46 Audio Sync 2015 The audio synchronization tool provides capability of synchronizing multiple contents in multiple devices.

Audio Profiles edit

 
Hierarchical structure of AAC Profile, HE-AAC Profile and HE-AAC v2 Profile, and compatibility between them. The HE-AAC Profile decoder is fully capable of decoding any AAC Profile stream. Similarly the HE-AAC v2 decoder can handle all HE-AAC Profile streams as well as all AAC Profile streams. Based on the MPEG-4 Part 3 technical specification.[21]

The MPEG-4 Audio standard defines several profiles. These profiles are based on the object types and each profile supports different list of object types. Each profile may also have several levels, which limit some parameters of the tools present in a profile. These parameters usually are the sampling rate and the number of audio channels decoded at the same time.

MPEG-4 Audio Profiles[19][21]
Audio Profile Audio Object Types First public release date
AAC Profile AAC LC 2003
High Efficiency AAC Profile AAC LC, SBR 2003
HE-AAC v2 Profile AAC LC, SBR, PS 2006
Main Audio Profile AAC Main, AAC LC, AAC SSR, AAC LTP, AAC Scalable, TwinVQ, CELP, HVXC, TTSI, Main synthesis 1999
Scalable Audio Profile AAC LC, AAC LTP, AAC Scalable, TwinVQ, CELP, HVXC, TTSI 1999
Speech Audio Profile CELP, HVXC, TTSI 1999
Synthetic Audio Profile TTSI, Main synthesis 1999
High Quality Audio Profile AAC LC, AAC LTP, AAC Scalable, CELP, ER AAC LC, ER AAC LTP, ER AAC Scalable, ER CELP 2000
Low Delay Audio Profile CELP, HVXC, TTSI, ER AAC LD, ER CELP, ER HVXC 2000
Natural Audio Profile AAC Main, AAC LC, AAC SSR, AAC LTP, AAC Scalable, TwinVQ, CELP, HVXC, TTSI, ER AAC LC, ER AAC LTP, ER AAC Scalable, ER TwinVQ, ER BSAC, ER AAC LD, ER CELP, ER HVXC, ER HILN, ER Parametric 2000
Mobile Audio Internetworking Profile ER AAC LC, ER AAC Scalable, ER TwinVQ, ER BSAC, ER AAC LD 2000
HD-AAC Profile AAC LC, SLS[45] 2009[46]
ALS Simple Profile ALS 2010[42][47]

Audio storage and transport edit

Multiplex, storage and transmission formats for MPEG-4 Audio[16]
Standard Description
Multiplex ISO/IEC 14496-1 MPEG-4 Multiplex scheme (M4Mux)[48]
Multiplex ISO/IEC 14496-3 Low Overhead Audio Transport Multiplex (LATM)
Storage ISO/IEC 14496-3 (informative) Audio Data Interchange Format (ADIF) – only for AAC
Storage ISO/IEC 14496-12 MPEG-4 file format (MP4) / ISO base media file format
Transmission ISO/IEC 14496-3 (informative) Audio Data Transport Stream (ADTS) – only for AAC
Transmission ISO/IEC 14496-3 Low Overhead Audio Stream (LOAS), based on LATM

There is no standard for transport of elementary streams over a channel, because the broad range of MPEG-4 applications have delivery requirements that are too wide to easily characterize with a single solution.

The capabilities of a transport layer and the communication between transport, multiplex, and demultiplex functions are described in the Delivery Multimedia Integration Framework (DMIF) in ISO/IEC 14496-6.[16] A wide variety of delivery mechanisms exist below this interface, e.g., MPEG transport stream, Real-time Transport Protocol (RTP), etc.

Transport in Real-time Transport Protocol is defined in RFC 3016 (RTP Payload Format for MPEG-4 Audio/Visual Streams), RFC 3640 (RTP Payload Format for Transport of MPEG-4 Elementary Streams), RFC 4281 (The Codecs Parameter for "Bucket" Media Types) and RFC 4337 (MIME Type Registration for MPEG-4).

LATM and LOAS were defined for natural audio applications, which do not require sophisticated object-based coding or other functions provided by MPEG-4 Systems.

Bifurcation in the AAC technical standard edit

Main article: Advanced Audio Coding

The Advanced Audio Coding in MPEG-4 Part 3 (MPEG-4 Audio) Subpart 4 was enhanced relative to the previous standard MPEG-2 Part 7 (Advanced Audio Coding), in order to provide better sound quality for a given encoding bitrate.

It is assumed that any Part 3 and Part 7 differences will be ironed out by the ISO standards body in the near future to avoid the possibility of future bitstream incompatibilities. At present there are no known player or codec incompatibilities due to the newness of the standard.

The MPEG-2 Part 7 standard (Advanced Audio Coding) was first published in 1997 and offers three default profiles:[49][50] Low Complexity profile (LC), Main profile and Scalable Sampling Rate profile (SSR).

The MPEG-4 Part 3 Subpart 4 (General Audio Coding) combined the profiles from MPEG-2 Part 7 with Perceptual Noise Substitution (PNS) and defined them as Audio Object Types (AAC LC, AAC Main, AAC SSR).[4]

HE-AAC edit

Main article: HE-AAC

High-Efficiency Advanced Audio Coding is an extension of AAC LC using spectral band replication (SBR), and Parametric Stereo (PS). It is designed to increase coding efficiency at low bitrates by using partial parametric representation of audio.

AAC-SSR edit

AAC Scalable Sample Rate was introduced by Sony to the MPEG-2 Part 7 and MPEG-4 Part 3 standards.[citation needed] It was first published in ISO/IEC 13818-7, Part 7: Advanced Audio Coding (AAC) in 1997.[49][50] The audio signal is first split into 4 bands using a 4 band polyphase quadrature filter bank. Then these 4 bands are further split using MDCTs with a size k of 32 or 256 samples. This is similar to normal AAC LC which uses MDCTs with a size k of 128 or 1024 directly on the audio signal.

The advantage of this technique is that short block switching can be done separately for every PQF band. So high frequencies can be encoded using a short block to enhance temporal resolution, low frequencies can be still encoded with high spectral resolution. However, due to aliasing between the 4 PQF bands coding efficiencies around (1,2,3) * fs/8 is worse than normal MPEG-4 AAC LC.[citation needed]

MPEG-4 AAC-SSR is very similar to ATRAC and ATRAC-3.

Why AAC-SSR was introduced edit

The idea behind AAC-SSR was not only the advantage listed above, but also the possibility of reducing the data rate by removing 1, 2 or 3 of the upper PQF bands. A very simple bitstream splitter can remove these bands and thus reduce the bitrate and sample rate.

Example:

  • 4 subbands: bitrate = 128 kbit/s, sample rate = 48 kHz, f_lowpass = 20 kHz
  • 3 subbands: bitrate ~ 120 kbit/s, sample rate = 48 kHz, f_lowpass = 18 kHz
  • 2 subbands: bitrate ~ 100 kbit/s, sample rate = 24 kHz, f_lowpass = 12 kHz
  • 1 subband: bitrate ~ 65 kbit/s, sample rate = 12 kHz, f_lowpass = 6 kHz

Note: although possible, the resulting quality is much worse than typical for this bitrate. So for normal 64 kbit/s AAC LC a bandwidth of 14–16 kHz is achieved by using intensity stereo and reduced NMRs. This degrades audible quality less than transmitting 6 kHz bandwidth with perfect quality.

BSAC edit

Bit Sliced Arithmetic Coding is an MPEG-4 standard (ISO/IEC 14496-3 subpart 4) for scalable audio coding. BSAC uses an alternative noiseless coding to AAC, with the rest of the processing being identical to AAC. This support for scalability allows for nearly transparent sound quality at 64 kbit/s and graceful degradation at lower bit rates. BSAC coding is best performed in the range of 40 kbit/s to 64 kbit/s, though it operates in the range of 16 kbit/s to 64 kbit/s. The AAC-BSAC codec is used in Digital Multimedia Broadcasting (DMB) applications.

Licensing edit

In 2002, the MPEG-4 Audio Licensing Committee selected the Via Licensing Corporation as the Licensing Administrator for the MPEG-4 Audio patent pool.[3][51][52]

See also edit

References edit

  1. ^ a b ISO (2009). "ISO/IEC 14496-3:2009 - Information technology -- Coding of audio-visual objects -- Part 3: Audio". ISO. Retrieved 2009-10-06.
  2. ^ a b ISO (1999). "ISO/IEC 14496-3:1999 - Information technology -- Coding of audio-visual objects -- Part 3: Audio". ISO. Retrieved 2009-10-06.
  3. ^ a b Business Wire (2002-12-02). "MPEG-4 Audio Licensing Committee Selects Via Licensing Corporation as Administrator; MPEG-4 Audio Licensing Committee Finalizing Terms for Audio Profile Licensing". The Free Library. Retrieved 2009-10-06. {{cite web}}: |author= has generic name (help)
  4. ^ a b c d Karlheinz Brandenburg; Oliver Kunz; Akihiko Sugiyama (1999). . chiariglione.org. Archived from the original on 2010-07-17. Retrieved 2009-10-06.
  5. ^ Karlheinz Brandenburg; Oliver Kunz; Akihiko Sugiyama. . chiariglione.org. Archived from the original on 2010-02-28. Retrieved 2009-10-06.
  6. ^ D. Thom, H. Purnhagen, and the MPEG Audio Subgroup (October 1998). "MPEG Audio FAQ – MPEG-4". chiariglione.org. Retrieved 2009-10-06.{{cite web}}: CS1 maint: multiple names: authors list (link)
  7. ^ a b c d ISO/IEC JTC 1/SC 29/WG 11 (July 1999), ISO/IEC 14496-3:/Amd.1 – Final Committee Draft – MPEG-4 Audio Version 2 (PDF), archived from the original (PDF) on 2012-08-01, retrieved 2009-10-07{{citation}}: CS1 maint: numeric names: authors list (link)
  8. ^ a b Heiko Purnhagen (1999-06-07), (PDF), Heiko Purnhagen, archived from the original (PDF) on 2017-07-06, retrieved 2009-10-07
  9. ^ a b Heiko Purnhagen (2001-06-01). "The MPEG-4 Audio Standard: Overview and Applications". Heiko Purnhagen. Retrieved 2009-10-07. [dead link]
  10. ^ Heiko Purnhagen (2001-11-07). "The MPEG Audio Web Page – MPEG-4 Audio (ISO/IEC 14496-3)". Retrieved 2009-10-07. [dead link]
  11. ^ Rob Koenen, ISO/IEC JTC1/SC29/WG11 (March 2002). "Overview of the MPEG-4 Standard". chiariglione.org. Retrieved 2009-10-06.{{cite web}}: CS1 maint: numeric names: authors list (link)
  12. ^ a b MPEG. . chiariglione.org. Archived from the original on April 20, 2010. Retrieved 2009-10-31.
  13. ^ ISO (2000). "ISO/IEC 14496-3:1999/Amd 1:2000 - Audio extensions". ISO. Retrieved 2009-10-07.
  14. ^ ISO (2001). "ISO/IEC 14496-3:2001 - Information technology -- Coding of audio-visual objects -- Part 3: Audio". ISO. Retrieved 2009-10-14.
  15. ^ ISO (2005). "ISO/IEC 14496-3:2005 - Information technology -- Coding of audio-visual objects -- Part 3: Audio". ISO. Retrieved 2009-10-14.
  16. ^ a b c d ISO/IEC (2009-09-01), ISO/IEC 14496-3:2009 - Information technology -- Coding of audio-visual objects -- Part 3: Audio (PDF), IEC, retrieved 2009-10-07
  17. ^ ISO/IEC (2019-12-01), ISO/IEC 14496-3:2019 - Information technology -- Coding of audio-visual objects -- Part 3: Audio, IEC, retrieved 2020-06-02
  18. ^ a b MultimediaWiki (2009). "MPEG-4 Audio". MultimediaWiki. Retrieved 2009-10-09.
  19. ^ a b c Bernhard Grill; Stefan Geyersberger; Johannes Hilpert; Bodo Teichmann (July 2004), (PDF), Fraunhofer Gesellschaft, archived from the original (PDF) on 2007-06-10, retrieved 2009-10-09
  20. ^ ISO/IEC JTC1/SC29/WG11 N2203 (March 1998). "MPEG-4 Audio (Final Committee Draft 14496-3)". Heiko Purnhagen. Retrieved 2009-10-07.{{cite web}}: CS1 maint: numeric names: authors list (link)[dead link]
  21. ^ a b c ISO/IEC JTC1/SC29/WG11/N7016 (2005-01-11), , archived from the original (DOC) on 2014-05-12, retrieved 2009-10-09{{citation}}: CS1 maint: numeric names: authors list (link)
  22. ^ a b Karlheinz Brandenburg; Oliver Kunz; Akihiko Sugiyama (1999). . chiariglione.org. Archived from the original on 2010-02-19. Retrieved 2009-10-06.
  23. ^ ISO (2003). "Bandwidth extension, ISO/IEC 14496-3:2001/Amd 1:2003". ISO. Retrieved 2009-10-13.
  24. ^ a b Scheirer, Eric D.; Ray, Lee (1998). "Algorithmic and Wavetable Synthesis in the MPEG-4 Multimedia Standard". Audio Engineering Society Convention 105, 1998. CiteSeerX 10.1.1.35.2773. 2.2 Wavetable synthesis with SASBF: The SASBF wavetable-bank format had a somewhat complex history of development. The original specification was contributed by E-Mu Systems and was based on their "SoundFont" format [15]. After integration of this component in the MPEG-4 reference software was complete, the MIDI Manufacturers Association (MMA) approached MPEG requesting that MPEG-4 SASBF be compatible with their "Downloaded Sounds" format [13]. E-Mu agreed that this compatibility was desirable, and so a new format was negotiated and designed collaboratively by all parties.
  25. ^ ISO (2004). "Parametric coding for high-quality audio, ISO/IEC 14496-3:2001/Amd 2:2004". ISO. Retrieved 2009-10-13.
  26. ^ ISO/IEC JTC1/SC29/WG11 (2003-07-25). . Archived from the original (DOC) on 2014-05-12. Retrieved 2009-10-13.{{cite web}}: CS1 maint: numeric names: authors list (link)
  27. ^ 3GPP (2004-09-30). "3GPP TS 26.401 V6.0.0 (2004-09), General Audio Codec audio processing functions; Enhanced aacPlus General Audio CodecGeneral Description (Release 6)" (DOC). 3GPP. Retrieved 2009-10-13.{{cite web}}: CS1 maint: numeric names: authors list (link)
  28. ^ 3GPP (2005-01-04). "ETSI TS 126 401 V6.1.0 (2004-12) - Universal Mobile Telecommunications System (UMTS)General audio codec audio processing functions; Enhanced aacPlus general audio codecGeneral description (3GPP TS 26.401 version 6.1.0 Release 6)". 3GPP. Retrieved 2009-10-13.{{cite web}}: CS1 maint: numeric names: authors list (link)
  29. ^ a b ISO (2006). "Audio Lossless Coding (ALS), new audio profiles and BSAC extensions, ISO/IEC 14496-3:2005/Amd 2:2006". ISO. Retrieved 2009-10-13.
  30. ^ ISO (2007). "BSAC extensions and transport of MPEG Surround, ISO/IEC 14496-3:2005/Amd 5:2007". ISO. Retrieved 2009-10-13.
  31. ^ ISO/IEC JTC1/SC29/WG11 (July 2005). . Archived from the original on 2010-04-30. Retrieved 2010-02-09.{{cite web}}: CS1 maint: numeric names: authors list (link)
  32. ^ ISO/IEC JTC1/SC29/WG11 (July 2005). . Archived from the original on 2008-03-24. Retrieved 2010-02-09.{{cite web}}: CS1 maint: numeric names: authors list (link)
  33. ^ ISO (2007-01-29). "ISO/IEC 23003-1:2007 - Information technology -- MPEG audio technologies -- Part 1: MPEG Surround". ISO. Retrieved 2009-10-24.
  34. ^ a b c ISO (2005). "MPEG-1/2 audio in MPEG-4, ISO/IEC 14496-3:2001/Amd 3:2005". ISO. Retrieved 2009-10-13.
  35. ^ ISO (2005). "Lossless coding of oversampled audio, ISO/IEC 14496-3:2001/Amd 6:2005". ISO. Retrieved 2009-10-13.
  36. ^ ISO (2006). "Scalable Lossless Coding (SLS), ISO/IEC 14496-3:2005/Amd 3:2006". ISO. Retrieved 2009-10-13.
  37. ^ ISO (2008). "Enhanced low delay AAC, ISO/IEC 14496-3:2005/Amd 9:2008". ISO. Retrieved 2009-10-13.
  38. ^ ISO (2008). "ISO/IEC 14496-23:2008, Information technology -- Coding of audio-visual objects -- Part 23: Symbolic Music Representation". ISO. Retrieved 2009-10-13.
  39. ^ ISO (2008). "Symbolic Music Representation conformance, ISO/IEC 14496-4:2004/Amd 29:2008". ISO. Retrieved 2009-10-13.
  40. ^ ISO (2012). "ISO/IEC 23003-3:2012 - Information technology -- MPEG audio technologies -- Part 3: Unified speech and audio coding". ISO. Retrieved 2019-11-07.
  41. ^ ISO (2009). "ISO/IEC 14496-3:2009/Amd 2:2010, ALS simple profile and transport of SAOC". ISO. Retrieved 2009-10-13.
  42. ^ a b ISO/IEC JTC1/SC29/WG11 (2009-07-03), , archived from the original (DOC) on 2014-07-29, retrieved 2009-10-13{{citation}}: CS1 maint: numeric names: authors list (link)
  43. ^ a b ISO (2010). "ISO/IEC 23003-2:2010 - Information technology -- MPEG audio technologies -- Part 2: Spatial Audio Object Coding (SAOC)". ISO. Retrieved 2010-12-27.
  44. ^ AES Convention Paper 8099 – A new parametric stereo and Multi Channel Extension for MPEG-4 Enhanced Low Delay AAC (AAC-ELD) (PDF), retrieved 2019-11-07
  45. ^ ISO/IEC JTC1/SC29/WG11 (2008-10-17), , archived from the original (DOC) on 2014-05-12, retrieved 2009-10-19{{citation}}: CS1 maint: numeric names: authors list (link)
  46. ^ ISO (2009-09-11). "ISO/IEC 14496-3:2009/Amd 1:2009 - HD-AAC profile and MPEG Surround signaling". ISO. Retrieved 2009-10-15.
  47. ^ ISO (2009-10-08). "ISO/IEC 14496-3:2009/Amd 2:2010 - ALS simple profile and transport of SAOC". ISO. Retrieved 2009-10-15.
  48. ^ ISO (2004-11-15), (PDF), ISO, archived from the original (PDF) on June 14, 2011, retrieved 2009-10-14
  49. ^ a b ISO (2004-10-15), (PDF), p. 32, archived from the original (PDF) on 2011-07-13, retrieved 2009-10-19
  50. ^ a b ISO (1997). "ISO/IEC 13818-7:1997, Information technology -- Generic coding of moving pictures and associated audio information -- Part 7: Advanced Audio Coding (AAC)". Retrieved 2009-10-19.
  51. ^ Business Wire (2009-01-05). "Via Licensing Announces MPEG-4 SLS Patent Pool License". Reuters. Archived from the original on 2013-01-04. Retrieved 2009-10-09. {{cite web}}: |author= has generic name (help)
  52. ^ Via Licensing Corporation (2009-05-12). "Via Licensing Announces the Availability of an MPEG-4 SLS Joint Patent Licensing Program". Business Wire. Retrieved 2009-10-09.

External links edit

  • "AAC" (VideoLAN WIKI)
  • EBU subjective listening tests on low-bitrate audio codecs 2007-02-16 at the Wayback Machine
  • AAC radio stations – Online radio stations in AAC format
  • – Directory of radio stations in AAC+ format at various bitrates
  • RadioFeeds UK & Ireland – Page containing plenty of terrestrial stations webcasting in AAC+ format.
  • A page comparing codecs including HE-AAC @64 kbit/s by listening tests. (Page is offline)
  • Official MPEG web site
  • RFC 3016 – RTP Payload Format for MPEG-4 Audio/Visual Streams
  • RFC 3640 – RTP Payload Format for Transport of MPEG-4 Elementary Streams
  • RFC 4281 – The Codecs Parameter for "Bucket" Media Types
  • RFC 4337 – MIME Type Registration for MPEG-4

January 01, 1970
mpeg, part, mpeg, audio, formally, 14496, third, part, mpeg, international, standard, developed, moving, picture, experts, group, specifies, audio, coding, methods, first, version, 14496, published, 1999, consists, variety, audio, coding, technologies, from, l. MPEG 4 Part 3 or MPEG 4 Audio formally ISO IEC 14496 3 is the third part of the ISO IEC MPEG 4 international standard developed by Moving Picture Experts Group 1 It specifies audio coding methods The first version of ISO IEC 14496 3 was published in 1999 2 The MPEG 4 Part 3 consists of a variety of audio coding technologies from lossy speech coding HVXC CELP general audio coding AAC TwinVQ BSAC lossless audio compression MPEG 4 SLS Audio Lossless Coding MPEG 4 DST a Text To Speech Interface TTSI Structured Audio using SAOL SASL MIDI and many additional audio synthesis and coding techniques 3 4 5 6 7 8 9 10 11 MPEG 4 Audio does not target a single application such as real time telephony or high quality audio compression It applies to every application which requires the use of advanced sound compression synthesis manipulation or playback MPEG 4 Audio is a new type of audio standard that integrates numerous different types of audio coding natural sound and synthetic sound low bitrate delivery and high quality delivery speech and music complex soundtracks and simple ones traditional content and interactive content 7 Contents 1 Versions 2 Subparts 3 MPEG 4 Audio Object Types 4 Audio Profiles 5 Audio storage and transport 6 Bifurcation in the AAC technical standard 7 HE AAC 8 AAC SSR 8 1 Why AAC SSR was introduced 9 BSAC 10 Licensing 11 See also 12 References 13 External linksVersions editMPEG 4 Audio versions and editions 12 Edition Release date Latest amendment Standard Description First edition 1999 2001 ISO IEC 14496 3 1999 2 also known as MPEG 4 Audio Version 1 2000 ISO IEC 14496 3 1999 Amd 1 2000 13 also known as MPEG 4 Audio Version 2 an Amendment to first edition 7 8 Second edition 2001 2005 ISO IEC 14496 3 2001 14 Third edition 2005 2008 ISO IEC 14496 3 2005 15 Fourth edition 2009 2015 and under development 12 ISO IEC 14496 3 2009 1 16 Fifth edition 2019 ISO IEC 14496 3 2019 17 Current versionSubparts editMPEG 4 Part 3 contains following subparts 16 Subpart 1 Main list of Audio Object Types Profiles Levels interface to ISO IEC 14496 1 MPEG 4 Audio transport stream etc Subpart 2 Speech coding HVXC Harmonic Vector eXcitation Coding Subpart 3 Speech coding CELP Code Excited Linear Prediction Subpart 4 General Audio Coding GA Time Frequency Coding AAC TwinVQ BSAC Subpart 5 Structured Audio SA Subpart 6 Text to Speech Interface TTSI Subpart 7 Parametric Audio Coding HILN Harmonic and Individual Line plus Noise Subpart 8 Technical description of parametric coding for high quality audio SSC Parametric Stereo Subpart 9 MPEG 1 MPEG 2 Audio in MPEG 4 Subpart 10 Technical description of lossless coding of oversampled audio MPEG 4 DST Direct Stream Transfer Subpart 11 Audio Lossless Coding ALS Subpart 12 Scalable Lossless Coding SLS MPEG 4 Audio Object Types editMPEG 4 Audio includes a system for handling a diverse group of audio formats in a uniform manner Each format is assigned a unique Audio Object Type to represent it 18 19 Object Type is used to distinguish between different coding methods It directly determines the MPEG 4 tool subset required to decode a specific object The MPEG 4 profiles are based on the object types and each profile supports a different list of object types 19 MPEG 4 Audio Object Types 7 9 18 20 21 Object Type ID Audio Object Type First public release date Description 1 AAC Main 1999 contains AAC LC 2 AAC LC Low Complexity 1999 Used in the AAC Profile MPEG 4 AAC LC Audio Object Type is based on the MPEG 2 Part 7 Low Complexity profile LC combined with Perceptual Noise Substitution PNS defined in MPEG 4 Part 3 Subpart 4 4 22 3 AAC SSR Scalable Sample Rate 1999 MPEG 4 AAC SSR Audio Object Type is based on the MPEG 2 Part 7 Scalable Sampling Rate profile SSR combined with Perceptual Noise Substitution PNS defined in MPEG 4 Part 3 Subpart 4 4 22 4 AAC LTP Long Term Prediction 1999 contains AAC LC 5 SBR Spectral Band Replication 2003 23 used with AAC LC in the High Efficiency AAC Profile HE AAC v1 6 AAC Scalable 1999 7 TwinVQ 1999 audio coding at very low bitrates 8 CELP Code Excited Linear Prediction 1999 speech coding 9 HVXC Harmonic Vector eXcitation Coding 1999 speech coding 10 Reserved 11 Reserved 12 TTSI Text To Speech Interface 1999 13 Main synthesis 1999 contains wavetable sample based synthesis 24 and Algorithmic Synthesis and Audio Effects 14 wavetable sample based synthesis 1999 based on SoundFont and DownLoadable Sounds 24 contains General MIDI 15 General MIDI 1999 16 Algorithmic Synthesis and Audio Effects 1999 17 ER AAC LC 2000 Error Resilient 18 Reserved 19 ER AAC LTP 2000 Error Resilient 20 ER AAC Scalable 2000 Error Resilient 21 ER TwinVQ 2000 Error Resilient 22 ER BSAC Bit Sliced Arithmetic Coding 2000 It is also known as Fine Granule Audio or fine grain scalability tool It is used in combination with the AAC coding tools and replaces the noiseless coding and the bitstream formatting of MPEG 4 Version 1 GA coder Error Resilient 23 ER AAC LD Low Delay 2000 Error Resilient used with CELP ER CELP HVXC ER HVXC and TTSI in the Low Delay Profile commonly used for real time conversation applications 24 ER CELP 2000 Error Resilient 25 ER HVXC 2000 Error Resilient 26 ER HILN Harmonic and Individual Lines plus Noise 2000 Error Resilient 27 ER Parametric 2000 Error Resilient 28 SSC SinuSoidal Coding 2004 25 26 29 PS Parametric Stereo 2004 27 and 2006 28 29 used with AAC LC and SBR in the HE AAC v2 Profile PS coding tool was defined in 2004 and Object Type defined in 2006 30 MPEG Surround 2007 30 also known as MPEG Spatial Audio Coding SAC it is a type of spatial audio coding 31 32 MPEG Surround was also defined in ISO IEC 23003 1 in 2007 33 31 ESCAPE 32 MPEG 1 2 Layer 1 2005 34 33 MPEG 1 2 Layer 2 2005 34 34 MPEG 1 2 Layer 3 2005 34 also known as MP3onMP4 35 DST Direct Stream Transfer 2005 35 lossless audio coding used on Super Audio CD 36 ALS Audio Lossless Coding 2006 29 lossless audio coding 37 SLS Scalable Lossless Coding 2006 36 two layer audio coding with lossless layer and lossy General Audio core layer e g AAC 38 SLS non core 2006 lossless audio coding without lossy General Audio core layer e g AAC 39 ER AAC ELD Enhanced Low Delay 2008 37 Error Resilient 40 SMR Symbolic Music Representation Simple 2008 note Symbolic Music Representation is also the MPEG 4 Part 23 standard ISO IEC 14496 23 2008 38 39 41 SMR Main 2008 42 USAC Unified Speech and Audio Coding 2012 Unified Speech and audio Coding is defined in MPEG D Part 3 ISO IEC 23003 3 2012 40 43 SAOC Spatial Audio Object Coding 2010 41 42 note Spatial Audio Object Coding is also the MPEG D Part 2 standard ISO IEC 23003 2 2010 43 44 LD MPEG Surround 2010 44 This object type conveys Low Delay MPEG Surround Coding side information that was defined in MPEG D Part 2 ISO IEC 23003 2 43 in the MPEG 4 Audio framework 45 SAOC DE 2013 Spatial Audio Object Coding Dialogue Enhancement 46 Audio Sync 2015 The audio synchronization tool provides capability of synchronizing multiple contents in multiple devices Audio Profiles edit nbsp Hierarchical structure of AAC Profile HE AAC Profile and HE AAC v2 Profile and compatibility between them The HE AAC Profile decoder is fully capable of decoding any AAC Profile stream Similarly the HE AAC v2 decoder can handle all HE AAC Profile streams as well as all AAC Profile streams Based on the MPEG 4 Part 3 technical specification 21 The MPEG 4 Audio standard defines several profiles These profiles are based on the object types and each profile supports different list of object types Each profile may also have several levels which limit some parameters of the tools present in a profile These parameters usually are the sampling rate and the number of audio channels decoded at the same time MPEG 4 Audio Profiles 19 21 Audio Profile Audio Object Types First public release date AAC Profile AAC LC 2003 High Efficiency AAC Profile AAC LC SBR 2003 HE AAC v2 Profile AAC LC SBR PS 2006 Main Audio Profile AAC Main AAC LC AAC SSR AAC LTP AAC Scalable TwinVQ CELP HVXC TTSI Main synthesis 1999 Scalable Audio Profile AAC LC AAC LTP AAC Scalable TwinVQ CELP HVXC TTSI 1999 Speech Audio Profile CELP HVXC TTSI 1999 Synthetic Audio Profile TTSI Main synthesis 1999 High Quality Audio Profile AAC LC AAC LTP AAC Scalable CELP ER AAC LC ER AAC LTP ER AAC Scalable ER CELP 2000 Low Delay Audio Profile CELP HVXC TTSI ER AAC LD ER CELP ER HVXC 2000 Natural Audio Profile AAC Main AAC LC AAC SSR AAC LTP AAC Scalable TwinVQ CELP HVXC TTSI ER AAC LC ER AAC LTP ER AAC Scalable ER TwinVQ ER BSAC ER AAC LD ER CELP ER HVXC ER HILN ER Parametric 2000 Mobile Audio Internetworking Profile ER AAC LC ER AAC Scalable ER TwinVQ ER BSAC ER AAC LD 2000 HD AAC Profile AAC LC SLS 45 2009 46 ALS Simple Profile ALS 2010 42 47 Audio storage and transport editMultiplex storage and transmission formats for MPEG 4 Audio 16 Standard Description Multiplex ISO IEC 14496 1 MPEG 4 Multiplex scheme M4Mux 48 Multiplex ISO IEC 14496 3 Low Overhead Audio Transport Multiplex LATM Storage ISO IEC 14496 3 informative Audio Data Interchange Format ADIF only for AAC Storage ISO IEC 14496 12 MPEG 4 file format MP4 ISO base media file format Transmission ISO IEC 14496 3 informative Audio Data Transport Stream ADTS only for AAC Transmission ISO IEC 14496 3 Low Overhead Audio Stream LOAS based on LATM There is no standard for transport of elementary streams over a channel because the broad range of MPEG 4 applications have delivery requirements that are too wide to easily characterize with a single solution The capabilities of a transport layer and the communication between transport multiplex and demultiplex functions are described in the Delivery Multimedia Integration Framework DMIF in ISO IEC 14496 6 16 A wide variety of delivery mechanisms exist below this interface e g MPEG transport stream Real time Transport Protocol RTP etc Transport in Real time Transport Protocol is defined in RFC 3016 RTP Payload Format for MPEG 4 Audio Visual Streams RFC 3640 RTP Payload Format for Transport of MPEG 4 Elementary Streams RFC 4281 The Codecs Parameter for Bucket Media Types and RFC 4337 MIME Type Registration for MPEG 4 LATM and LOAS were defined for natural audio applications which do not require sophisticated object based coding or other functions provided by MPEG 4 Systems Bifurcation in the AAC technical standard editMain article Advanced Audio Coding The Advanced Audio Coding in MPEG 4 Part 3 MPEG 4 Audio Subpart 4 was enhanced relative to the previous standard MPEG 2 Part 7 Advanced Audio Coding in order to provide better sound quality for a given encoding bitrate It is assumed that any Part 3 and Part 7 differences will be ironed out by the ISO standards body in the near future to avoid the possibility of future bitstream incompatibilities At present there are no known player or codec incompatibilities due to the newness of the standard The MPEG 2 Part 7 standard Advanced Audio Coding was first published in 1997 and offers three default profiles 49 50 Low Complexity profile LC Main profile and Scalable Sampling Rate profile SSR The MPEG 4 Part 3 Subpart 4 General Audio Coding combined the profiles from MPEG 2 Part 7 with Perceptual Noise Substitution PNS and defined them as Audio Object Types AAC LC AAC Main AAC SSR 4 HE AAC editMain article HE AAC High Efficiency Advanced Audio Coding is an extension of AAC LC using spectral band replication SBR and Parametric Stereo PS It is designed to increase coding efficiency at low bitrates by using partial parametric representation of audio AAC SSR editAAC Scalable Sample Rate was introduced by Sony to the MPEG 2 Part 7 and MPEG 4 Part 3 standards citation needed It was first published in ISO IEC 13818 7 Part 7 Advanced Audio Coding AAC in 1997 49 50 The audio signal is first split into 4 bands using a 4 band polyphase quadrature filter bank Then these 4 bands are further split using MDCTs with a size k of 32 or 256 samples This is similar to normal AAC LC which uses MDCTs with a size k of 128 or 1024 directly on the audio signal The advantage of this technique is that short block switching can be done separately for every PQF band So high frequencies can be encoded using a short block to enhance temporal resolution low frequencies can be still encoded with high spectral resolution However due to aliasing between the 4 PQF bands coding efficiencies around 1 2 3 fs 8 is worse than normal MPEG 4 AAC LC citation needed MPEG 4 AAC SSR is very similar to ATRAC and ATRAC 3 Why AAC SSR was introduced edit The idea behind AAC SSR was not only the advantage listed above but also the possibility of reducing the data rate by removing 1 2 or 3 of the upper PQF bands A very simple bitstream splitter can remove these bands and thus reduce the bitrate and sample rate Example 4 subbands bitrate 128 kbit s sample rate 48 kHz f lowpass 20 kHz 3 subbands bitrate 120 kbit s sample rate 48 kHz f lowpass 18 kHz 2 subbands bitrate 100 kbit s sample rate 24 kHz f lowpass 12 kHz 1 subband bitrate 65 kbit s sample rate 12 kHz f lowpass 6 kHz Note although possible the resulting quality is much worse than typical for this bitrate So for normal 64 kbit s AAC LC a bandwidth of 14 16 kHz is achieved by using intensity stereo and reduced NMRs This degrades audible quality less than transmitting 6 kHz bandwidth with perfect quality BSAC editBit Sliced Arithmetic Coding is an MPEG 4 standard ISO IEC 14496 3 subpart 4 for scalable audio coding BSAC uses an alternative noiseless coding to AAC with the rest of the processing being identical to AAC This support for scalability allows for nearly transparent sound quality at 64 kbit s and graceful degradation at lower bit rates BSAC coding is best performed in the range of 40 kbit s to 64 kbit s though it operates in the range of 16 kbit s to 64 kbit s The AAC BSAC codec is used in Digital Multimedia Broadcasting DMB applications Licensing editIn 2002 the MPEG 4 Audio Licensing Committee selected the Via Licensing Corporation as the Licensing Administrator for the MPEG 4 Audio patent pool 3 51 52 See also editTwinVQ one of the object types defined in MPEG 4 Audio version 1 MPEG 4 Part 2 MPEG 4 Part 14 container format MP4 Digital rights management Advanced Audio Coding AAC ISO IEC JTC 1 SC 29References edit a b ISO 2009 ISO IEC 14496 3 2009 Information technology Coding of audio visual objects Part 3 Audio ISO Retrieved 2009 10 06 a b ISO 1999 ISO IEC 14496 3 1999 Information technology Coding of audio visual objects Part 3 Audio ISO Retrieved 2009 10 06 a b Business Wire 2002 12 02 MPEG 4 Audio Licensing Committee Selects Via Licensing Corporation as Administrator MPEG 4 Audio Licensing Committee Finalizing Terms for Audio Profile Licensing The Free Library Retrieved 2009 10 06 a href Template Cite web html title Template Cite web cite web a author has generic name help a b c d Karlheinz Brandenburg Oliver Kunz Akihiko Sugiyama 1999 MPEG 4 Natural Audio Coding Audio profiles and levels chiariglione org Archived from the original on 2010 07 17 Retrieved 2009 10 06 Karlheinz Brandenburg Oliver Kunz Akihiko Sugiyama MPEG 4 Natural Audio Coding scalability in MPEG 4 natural audio chiariglione org Archived from the original on 2010 02 28 Retrieved 2009 10 06 D Thom H Purnhagen and the MPEG Audio Subgroup October 1998 MPEG Audio FAQ MPEG 4 chiariglione org Retrieved 2009 10 06 a href Template Cite web html title Template Cite web cite web a CS1 maint multiple names authors list link a b c d ISO IEC JTC 1 SC 29 WG 11 July 1999 ISO IEC 14496 3 Amd 1 Final Committee Draft MPEG 4 Audio Version 2 PDF archived from the original PDF on 2012 08 01 retrieved 2009 10 07 a href Template Citation html title Template Citation citation a CS1 maint numeric names authors list link a b Heiko Purnhagen 1999 06 07 An Overview of MPEG 4 Audio Version 2 PDF Heiko Purnhagen archived from the original PDF on 2017 07 06 retrieved 2009 10 07 a b Heiko Purnhagen 2001 06 01 The MPEG 4 Audio Standard Overview and Applications Heiko Purnhagen Retrieved 2009 10 07 dead link Heiko Purnhagen 2001 11 07 The MPEG Audio Web Page MPEG 4 Audio ISO IEC 14496 3 Retrieved 2009 10 07 dead link Rob Koenen ISO IEC JTC1 SC29 WG11 March 2002 Overview of the MPEG 4 Standard chiariglione org Retrieved 2009 10 06 a href Template Cite web html title Template Cite web cite web a CS1 maint numeric names authors list link a b MPEG MPEG standards Full list of standards developed or under development chiariglione org Archived from the original on April 20 2010 Retrieved 2009 10 31 ISO 2000 ISO IEC 14496 3 1999 Amd 1 2000 Audio extensions ISO Retrieved 2009 10 07 ISO 2001 ISO IEC 14496 3 2001 Information technology Coding of audio visual objects Part 3 Audio ISO Retrieved 2009 10 14 ISO 2005 ISO IEC 14496 3 2005 Information technology Coding of audio visual objects Part 3 Audio ISO Retrieved 2009 10 14 a b c d ISO IEC 2009 09 01 ISO IEC 14496 3 2009 Information technology Coding of audio visual objects Part 3 Audio PDF IEC retrieved 2009 10 07 ISO IEC 2019 12 01 ISO IEC 14496 3 2019 Information technology Coding of audio visual objects Part 3 Audio IEC retrieved 2020 06 02 a b MultimediaWiki 2009 MPEG 4 Audio MultimediaWiki Retrieved 2009 10 09 a b c Bernhard Grill Stefan Geyersberger Johannes Hilpert Bodo Teichmann July 2004 Implementation of MPEG 4 Audio Components on various Platforms PDF Fraunhofer Gesellschaft archived from the original PDF on 2007 06 10 retrieved 2009 10 09 ISO IEC JTC1 SC29 WG11 N2203 March 1998 MPEG 4 Audio Final Committee Draft 14496 3 Heiko Purnhagen Retrieved 2009 10 07 a href Template Cite web html title Template Cite web cite web a CS1 maint numeric names authors list link dead link a b c ISO IEC JTC1 SC29 WG11 N7016 2005 01 11 Text of ISO IEC 14496 3 2001 FPDAM 4 Audio Lossless Coding ALS new audio profiles and BSAC extensions archived from the original DOC on 2014 05 12 retrieved 2009 10 09 a href Template Citation html title Template Citation citation a CS1 maint numeric names authors list link a b Karlheinz Brandenburg Oliver Kunz Akihiko Sugiyama 1999 MPEG 4 Natural Audio Coding General Audio Coding AAC based chiariglione org Archived from the original on 2010 02 19 Retrieved 2009 10 06 ISO 2003 Bandwidth extension ISO IEC 14496 3 2001 Amd 1 2003 ISO Retrieved 2009 10 13 a b Scheirer Eric D Ray Lee 1998 Algorithmic and Wavetable Synthesis in the MPEG 4 Multimedia Standard Audio Engineering Society Convention 105 1998 CiteSeerX 10 1 1 35 2773 2 2 Wavetable synthesis with SASBF The SASBF wavetable bank format had a somewhat complex history of development The original specification was contributed by E Mu Systems and was based on their SoundFont format 15 After integration of this component in the MPEG 4 reference software was complete the MIDI Manufacturers Association MMA approached MPEG requesting that MPEG 4 SASBF be compatible with their Downloaded Sounds format 13 E Mu agreed that this compatibility was desirable and so a new format was negotiated and designed collaboratively by all parties ISO 2004 Parametric coding for high quality audio ISO IEC 14496 3 2001 Amd 2 2004 ISO Retrieved 2009 10 13 ISO IEC JTC1 SC29 WG11 2003 07 25 Text of ISO IEC 14496 3 2001 FPDAM2 Parametric Audio N5713 Archived from the original DOC on 2014 05 12 Retrieved 2009 10 13 a href Template Cite web html title Template Cite web cite web a CS1 maint numeric names authors list link 3GPP 2004 09 30 3GPP TS 26 401 V6 0 0 2004 09 General Audio Codec audio processing functions Enhanced aacPlus General Audio CodecGeneral Description Release 6 DOC 3GPP Retrieved 2009 10 13 a href Template Cite web html title Template Cite web cite web a CS1 maint numeric names authors list link 3GPP 2005 01 04 ETSI TS 126 401 V6 1 0 2004 12 Universal Mobile Telecommunications System UMTS General audio codec audio processing functions Enhanced aacPlus general audio codecGeneral description 3GPP TS 26 401 version 6 1 0 Release 6 3GPP Retrieved 2009 10 13 a href Template Cite web html title Template Cite web cite web a CS1 maint numeric names authors list link a b ISO 2006 Audio Lossless Coding ALS new audio profiles and BSAC extensions ISO IEC 14496 3 2005 Amd 2 2006 ISO Retrieved 2009 10 13 ISO 2007 BSAC extensions and transport of MPEG Surround ISO IEC 14496 3 2005 Amd 5 2007 ISO Retrieved 2009 10 13 ISO IEC JTC1 SC29 WG11 July 2005 Tutorial on MPEG Surround Audio Coding Archived from the original on 2010 04 30 Retrieved 2010 02 09 a href Template Cite web html title Template Cite web cite web a CS1 maint numeric names authors list link ISO IEC JTC1 SC29 WG11 July 2005 Tutorial on MPEG Surround Audio Coding Archived from the original on 2008 03 24 Retrieved 2010 02 09 a href Template Cite web html title Template Cite web cite web a CS1 maint numeric names authors list link ISO 2007 01 29 ISO IEC 23003 1 2007 Information technology MPEG audio technologies Part 1 MPEG Surround ISO Retrieved 2009 10 24 a b c ISO 2005 MPEG 1 2 audio in MPEG 4 ISO IEC 14496 3 2001 Amd 3 2005 ISO Retrieved 2009 10 13 ISO 2005 Lossless coding of oversampled audio ISO IEC 14496 3 2001 Amd 6 2005 ISO Retrieved 2009 10 13 ISO 2006 Scalable Lossless Coding SLS ISO IEC 14496 3 2005 Amd 3 2006 ISO Retrieved 2009 10 13 ISO 2008 Enhanced low delay AAC ISO IEC 14496 3 2005 Amd 9 2008 ISO Retrieved 2009 10 13 ISO 2008 ISO IEC 14496 23 2008 Information technology Coding of audio visual objects Part 23 Symbolic Music Representation ISO Retrieved 2009 10 13 ISO 2008 Symbolic Music Representation conformance ISO IEC 14496 4 2004 Amd 29 2008 ISO Retrieved 2009 10 13 ISO 2012 ISO IEC 23003 3 2012 Information technology MPEG audio technologies Part 3 Unified speech and audio coding ISO Retrieved 2019 11 07 ISO 2009 ISO IEC 14496 3 2009 Amd 2 2010 ALS simple profile and transport of SAOC ISO Retrieved 2009 10 13 a b ISO IEC JTC1 SC29 WG11 2009 07 03 ISO IEC 14496 3 200X PDAM 2 ALS Simple Profile and Transport of SAOC N10826 archived from the original DOC on 2014 07 29 retrieved 2009 10 13 a href Template Citation html title Template Citation citation a CS1 maint numeric names authors list link a b ISO 2010 ISO IEC 23003 2 2010 Information technology MPEG audio technologies Part 2 Spatial Audio Object Coding SAOC ISO Retrieved 2010 12 27 AES Convention Paper 8099 A new parametric stereo and Multi Channel Extension for MPEG 4 Enhanced Low Delay AAC AAC ELD PDF retrieved 2019 11 07 ISO IEC JTC1 SC29 WG11 2008 10 17 ISO IEC 14496 3 2005 PDAM 10 200X HD AAC profile MPEG2008 N10188 archived from the original DOC on 2014 05 12 retrieved 2009 10 19 a href Template Citation html title Template Citation citation a CS1 maint numeric names authors list link ISO 2009 09 11 ISO IEC 14496 3 2009 Amd 1 2009 HD AAC profile and MPEG Surround signaling ISO Retrieved 2009 10 15 ISO 2009 10 08 ISO IEC 14496 3 2009 Amd 2 2010 ALS simple profile and transport of SAOC ISO Retrieved 2009 10 15 ISO 2004 11 15 ISO IEC 14496 1 Third edition 2004 11 15 Part 1 Systems PDF ISO archived from the original PDF on June 14 2011 retrieved 2009 10 14 a b ISO 2004 10 15 ISO IEC 13818 7 Third edition Part 7 Advanced Audio Coding AAC PDF p 32 archived from the original PDF on 2011 07 13 retrieved 2009 10 19 a b ISO 1997 ISO IEC 13818 7 1997 Information technology Generic coding of moving pictures and associated audio information Part 7 Advanced Audio Coding AAC Retrieved 2009 10 19 Business Wire 2009 01 05 Via Licensing Announces MPEG 4 SLS Patent Pool License Reuters Archived from the original on 2013 01 04 Retrieved 2009 10 09 a href Template Cite web html title Template Cite web cite web a author has generic name help Via Licensing Corporation 2009 05 12 Via Licensing Announces the Availability of an MPEG 4 SLS Joint Patent Licensing Program Business Wire Retrieved 2009 10 09 External links editApple MPEG 4 AAC AAC VideoLAN WIKI EBU subjective listening tests on low bitrate audio codecs Archived 2007 02 16 at the Wayback Machine AAC radio stations Online radio stations in AAC format Tuner2 Directory of radio stations in AAC format at various bitrates RadioFeeds UK amp Ireland Page containing plenty of terrestrial stations webcasting in AAC format Results of 64 kbit s Listening Test A page comparing codecs including HE AAC 64 kbit s by listening tests Page is offline Official MPEG web site RFC 3016 RTP Payload Format for MPEG 4 Audio Visual Streams RFC 3640 RTP Payload Format for Transport of MPEG 4 Elementary Streams RFC 4281 The Codecs Parameter for Bucket Media Types RFC 4337 MIME Type Registration for MPEG 4 Retrieved from https en wikipedia org w index php title MPEG 4 Part 3 amp oldid 1221580622, wikipedia, wiki, book, books, library,

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