MultimediaWiki - User contributions [en]

MP2

2012-05-23T19:33:21Z

Zorglub21: /* Open source implementations */

* Codec ID: 0x0050

MPEG-1 Audio Layer II (MP2) is an audio codec defined by ISO/IEC 11172-3. An extension exists: MPEG-2 Layer II and is defined in ISO/IEC 13818-3. It is the predecessor of [[MP3]].

[http://www.cmis.csiro.au/maaate/docs/layer2.txt Some useful information on MPEG Layer 2] (unreachable as of Dec 7th 2007)

===Open source encoder implementations===
*[http://sourceforge.net/projects/toolame/files/ TooLame], free software MPEG Layer II implementation with DAB support (Digital Audio Broadcasting)
*[http://www.twolame.org/ TwoLame], more recent free software implementation but DAB support broken

[[Category:Audio Codecs]]

MP2

2012-05-23T19:33:06Z

Zorglub21: /* Implementations */

* Codec ID: 0x0050

MPEG-1 Audio Layer II (MP2) is an audio codec defined by ISO/IEC 11172-3. An extension exists: MPEG-2 Layer II and is defined in ISO/IEC 13818-3. It is the predecessor of [[MP3]].

[http://www.cmis.csiro.au/maaate/docs/layer2.txt Some useful information on MPEG Layer 2] (unreachable as of Dec 7th 2007)

===Open source implementations===
*[http://sourceforge.net/projects/toolame/files/ TooLame], free software MPEG Layer II implementation with DAB support (Digital Audio Broadcasting)
*[http://www.twolame.org/ TwoLame], more recent free software implementation but DAB support broken

[[Category:Audio Codecs]]

Advanced Audio Coding

2012-05-23T19:27:03Z

Zorglub21: /* With Source Code */

* FourCC: AAC AACP MP4A mp4a VLB
* Company: [[ISO]]
* Samples: http://samples.mplayerhq.hu/A-codecs/AAC/
* Samples: [http://standards.iso.org/ittf/PubliclyAvailableStandards/ISO_IEC_14496-4_2004_Conformance_Testing/audio_conformance/mpeg4audio-conformance/compressedMp4/ sample repo at standards.iso.org]
* Sample Docs: [http://standards.iso.org/ittf/PubliclyAvailableStandards/ISO_IEC_14496-4_2004_Conformance_Testing/audio_conformance/mpeg4audio-conformance/doc/fileNameConventions.html sample docs]

Specification links:
*AAC: [http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=53943 ISO/IEC 14496-3:2009], [ftp://ftp.tnt.uni-hannover.de/pub/MPEG/audio/mpeg4/documents/ Old (free) drafts]
*Conformance: [http://www.iso.org/iso/catalogue_detail.htm?csnumber=53750 ISO/IEC 14496-26:2010]
*Gapless: [http://www.iso.org/iso/catalogue_detail.htm?csnumber=46461 14496-24:2008], [http://www.itscj.ipsj.or.jp/sc29/open/29view/29n7733t.doc Draft]
*[http://www.3gpp.org/ftp/specs/html-info/26-series.htm ETSI 26.401-406]

Reference Sources:
*MPEG [[AAC Reference Software]]
*[http://www.3gpp.org/ftp/specs/html-info/26-series.htm ETSI 26.410-412]

Usually stored in an [[MP4]] container.

See also [[Understanding AAC]].

== Implementations ==

=== With Source Code ===
*[[Google]] has opensourced Android, which includes an Apache 2.0 licensed aac encoder and decoder:
**http://android.git.kernel.org/?p=platform/frameworks/base.git;a=tree;f=media/libstagefright/codecs;hb=HEAD
*[[Intel]] has source for its IPP based [[AAC]] decoder:
**http://www.intel.com/cd/software/products/asmo-na/eng/perflib/ipp/219967.htm
*[[Real|Real Networks]] has source for its Helix AAC fixedpoint decoder here:
**https://datatype.helixcommunity.org/2005/aacfixptdec
*[[FAAC]]/[[FAAD]]
**http://www.audiocoding.com
*FFmpeg/Libav
*HE-AAC encoder based on 3GPP reference implementation
**http://tipok.org.ua/node/17

=== Other Notables ===
*[[Nero]] has a well regarded freeware AAC encoder and decoder
**http://www.nero.com/enu/technologies-aac-codec.html
*[[Dolby Laboratories|Coding Technologies]] the inventor of [[Spectral Band Replication|SBR]] has a shareware encoder available in [[Winamp]]
**http://www.winamp.com
*[[Apple]] who popularized the format in its [[iTunes]] software has an encoders and decoders available in iTunes and [[QuickTime]]. [[Dolby]] was involved in its implementation. [http://support.apple.com/kb/HT2103]
**http://www.apple.com/itunes

=== Decoder Features ===

AAC decoder feature matrix
{| border="1" style="border: 1px #aaa solid; border-collapse: collapse;"
|-
! Decoder
! [http://streams.videolan.org/Mpeg_Conformance/ftp.iis.fhg.de/mpeg4audio-conformance/compressedMp4/al17_44.mp4 al17]
! [http://samples.mplayerhq.hu/A-codecs/AAC/channel_model/elem_id0.mp4 elem_id0]
! [http://samples.mplayerhq.hu/A-codecs/AAC/channel_model/bad_concat.mp4 bad_concat]
! [http://samples.mplayerhq.hu/A-codecs/AAC/channel_model/lfe_is_sce.mp4 lfe_is_sce]
! SBR
! PS
! [http://streams.videolan.org/Mpeg_Conformance/ftp.iis.fhg.de/mpeg4audio-conformance/compressedMp4/al07_44.mp4 CCE]
! [http://streams.videolan.org/Mpeg_Conformance/ftp.iis.fhg.de/mpeg4audio-conformance/compressedMp4/am00_44.mp4 Main]
! [http://streams.videolan.org/Mpeg_Conformance/ftp.iis.fhg.de/mpeg4audio-conformance/compressedMp4/ap01_48.mp4 LTP]
! [http://streams.videolan.org/Mpeg_Conformance/ftp.iis.fhg.de/mpeg4audio-conformance/compressedMp4/er_ad1000_22_ep0.mp4 ER AAC LC]
! [http://streams.videolan.org/Mpeg_Conformance/ftp.iis.fhg.de/mpeg4audio-conformance/compressedMp4/er_al10_44_ep0.mp4 ER AAC LD]
! [http://streams.videolan.org/Mpeg_Conformance/ftp.iis.fhg.de/mpeg4audio-conformance/compressedMp4/al00sf_44.mp4 AAC-960]
! [http://samples.mplayerhq.hu/A-codecs/AAC/aacPlusDecoderCheckPackage_v2.1/bitstreams/File1.aac ADTS (Implicit SBR+PS)]
! [http://samples.mplayerhq.hu/A-codecs/AAC/aacPlusDecoderCheckPackage_v2.1/bitstreams/File2.mp4 MP4 (Implicit SBR+PS)]
! [http://samples.mplayerhq.hu/A-codecs/AAC/aacPlusDecoderCheckPackage_v2.1/bitstreams/File3.mp4 MP4 (EBC SBR / Impl PS)]
! [http://samples.mplayerhq.hu/A-codecs/AAC/aacPlusDecoderCheckPackage_v2.1/bitstreams/File4.mp4 MP4 (EBC SBR / EBC PS)]
! [http://samples.mplayerhq.hu/A-codecs/AAC/aacPlusDecoderCheckPackage_v2.1/bitstreams/File5.mp4 MP4 (Impl SBR / ENBC PS)]
! [http://samples.mplayerhq.hu/A-codecs/AAC/aacPlusDecoderCheckPackage_v2.1/bitstreams/File6.3gp 3GPP (EBC SBR / Impl PS)]
! [http://samples.mplayerhq.hu/A-codecs/AAC/aacPlusDecoderCheckPackage_v2.1/bitstreams/File7.3gp 3GPP (ENBC SBR / Impl PS)]
|-
! mp4mcDec
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
|-
! libavcodec
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| No
| No
| No
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
|-
! libfaad2
| No
| Yes
| Yes
| Yes
| Yes
| Yes
| No
| Yes
| Yes
| No
| No
| Yes
| Yes
| Yes
| Yes
| Yes
| No
| Yes
| Yes
|-
! iTunes
| No
| No
| Yes
| No LFE
| Yes
| No?
| No
| No
| No
| No
| No
| No
| No
| No SBR
| No PS
| No PS
| No PS
| No PS
| No PS
|-
! WinAMP
| Yes
| Garbled
| No
| Yes
| Yes
| Yes
| No
| No
| No
| No
| No
| No
| Yes
| Yes
| Yes
| Yes
| Yes
| No
| No
|-
! Microsoft DTV-DVD Audio Decoder
| No
| Yes
| Yes
| No LFE
| Yes
| Yes
| Yes
| No
| No
| No
| No
| No
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
|}

== Common AAC Flavors ==

=== MPEG-2 AAC-LC ===
The basic subset of AAC that most other flavors and profiles are based on.

=== The AAC Profile (MPEG-4 AAC-LC) ===
MPEG-2 AAC-LC plus a Perceptual Noise Substitution (PNS) tool.

=== The HE-AAC Profile (v1 and v2) ===

HE-AAC (also known by the [[Dolby Laboratories|Dolby]] trade name [http://www.codingtechnologies.com/products/aacPlus.htm aacPlus]) is MPEG-4 AAC-LC + [[Spectral Band Replication|SBR (Spectral Band Replication)]] and HE-AAC v2 (aacPlus v2) is MPEG-4 AAC-LC + SBR + [http://www.codingtechnologies.com/products/paraSter.htm PS (Parametric Stereo)]. Standard AAC-LC decoders can decode HE-AAC encoded files/streams but without SBR and PS you do not get the full quality.

* See also
** [[MP3#mp3PRO|MP3PRO]] that also uses SBR.

=== MPEG-2/4 AAC Main ===
MPEG-2/4 AAC-LC plus a computationally intensive, intra-channel, inter-frame frequency domain prediction tool. Additionally this profile adds relaxation to the maximum TNS filter size, and time domain coupling. The details of the prediction tool are only given in ISO/IEC 13818-7 not in ISO/IEC 14496-3. In the wild this appears to be used in some [[Hulu]] streams.

=== MPEG-4 AAC LTP ===
MPEG-4 AAC-LC plus a less computationally intensive frequency domain prediction tool. This flavor is rarely seen in the wild. Despite being an MPEG-4 only flavor it can be embedded in an [[ADTS]] stream.

=== BSAC AAC ===
Bit Slice Arithmetic Coding (BSAC) is an alternate quantization and entropy coding scheme for AAC. It is used by the [[T-DMB]] broadcast standard.

== Extensions ==

=== GAIN headers ===

See http://mp3gain.sourceforge.net and [[MP3#GAIN (MP3Gain) header|MP3 GAIN header]].

=== MPEG Surround ===
[http://www.mpegsurround.com MPEG Surround] is a multichannel coding scheme that can used with any core coder audio but is most often used with (HE-)AAC and BSAC. MPEG Surround technology shares similar characteristics with PS (Parametric Stereo) used in HE-AAC v2 including mixing in the same [[SBR]] domain used by HE-AAC.

References:
*[http://mpeg.chiariglione.org/technologies/mpeg-d/mpd-mps/index.htm N7390: Tutorial on MPEG Surround Audio Coding]
*[http://web.archive.org/web/20071008044710/http://www.codingtechnologies.com/products/mpgsrnd.htm Coding Technologies product page]

== AAC Encoding Guidelines ==
The following documents are must reads for anyone implementing an AAC encoder
* ISO/IEC 14496-3:2009 - Decoding AAC, systems MPEG-4 integration
* ISO/IEC 14496-26:2010 - Conformance, includes limits on various bitstream values
* ISO/IEC 14496-24:2008 - ISO Gapless AAC
* ISO/IEC 13818-7:2006 - MPEG-2 AAC includes informative annexes on encoding omitted from 14496-3
* 3GPP 26.403-405 - Elaborations on the annexes in 13818-7
* [http://www.mp3-tech.org/programmer/docs/di042001.pdf Improved ISO AAC Coder, Ivan Dimkovic, PsyTEL Research]

[[Category:Audio Codecs]]
[[Category: MDCT Audio Codecs]]
[[Category: Multichannel Audio Codecs]]

AAC Reference Software

2012-05-23T19:25:38Z

Zorglub21: /* 3GPP Reference implementation */

==Building==

===MPEG-4 Audio Reference Software===
*Latest Public Release http://standards.iso.org/ittf/PubliclyAvailableStandards/c050470__ISO_IEC_14496-5_2001_Amd_20_2009_Reference_Software.zip

===Dependencies===
*AFsp: ftp://ftp.tnt.uni-hannover.de/pub/audio/AFsp/AFsp-v8r2.tar.gz
*Systems: http://standards.iso.org/ittf/PubliclyAvailableStandards/c045527_ISO_IEC_14496-5_2001_Amd_12_2007_Reference_Software.zip

The systems software appears to have at least one bug that makes it difficult to use it to mux various AAC formats to mp4. [http://lists.mpegif.org/pipermail/mp4-tech/2009-February/008672.html] A newer version is available at request from the [http://www.mp4ra.org MP4 Registration Authority] ([[Apple]])

===Build Process===
*The software is not 64-bit safe. On a 64-bit system "-m32" should be added to CFLAGS and LDFLAGS.
*Build AFsp and libisomediafile
*Set up environment variables in the make-all script
*Select "kits" to build, the important kits for AAC/HE-AAC decoding are:
**mp4mcDec - reference decoder and file format converter
**conf_ssnrcd - Segmental SNR and cepstral distortion tool
**conf_pns - PNS conformance tool
**conf_sbr - SBR conformance tool
*Create a set of NOSBRKITS like LPSBRKITS set and give them the parameters SBR=0 PARAMETRICSTEREO=0. Include mp4mcDec in this set. This can be used to decode AAC files without SBR to test the core decoder of on an HE-AAC file.

==Usage==

Run any tool with no arguments to see usage information.

====mp4mcDec====
mp4audec_mc [options] aacfile pcmfile

useful options:

-3 create 24-bit output files

-D<string> print out various bits of diagnostic info

Debug options:
v verbose
V show all tools used
N show frame numbers
h show header info
c debug channel coupling
f debug scalefactors
i debug intensity stereo
m debug mid/side stereo
p debug prediction
P debug PNS and pulse data
q debug quantization
r debug prediction resets
s debug sfb (scale factor band) information
R debug DRC (dynamic range control)
T debug TNS
w debug window sequences
x show DSE and FIL elements
X show DSE contents

==3GPP Reference implementation==
*HE-AAC Reference implementation http://www.3gpp.org/ftp/Specs/html-info/26410.htm

AAC Reference Software

2012-05-23T19:25:19Z

Zorglub21:

==Building==

===MPEG-4 Audio Reference Software===
*Latest Public Release http://standards.iso.org/ittf/PubliclyAvailableStandards/c050470__ISO_IEC_14496-5_2001_Amd_20_2009_Reference_Software.zip

===Dependencies===
*AFsp: ftp://ftp.tnt.uni-hannover.de/pub/audio/AFsp/AFsp-v8r2.tar.gz
*Systems: http://standards.iso.org/ittf/PubliclyAvailableStandards/c045527_ISO_IEC_14496-5_2001_Amd_12_2007_Reference_Software.zip

The systems software appears to have at least one bug that makes it difficult to use it to mux various AAC formats to mp4. [http://lists.mpegif.org/pipermail/mp4-tech/2009-February/008672.html] A newer version is available at request from the [http://www.mp4ra.org MP4 Registration Authority] ([[Apple]])

===Build Process===
*The software is not 64-bit safe. On a 64-bit system "-m32" should be added to CFLAGS and LDFLAGS.
*Build AFsp and libisomediafile
*Set up environment variables in the make-all script
*Select "kits" to build, the important kits for AAC/HE-AAC decoding are:
**mp4mcDec - reference decoder and file format converter
**conf_ssnrcd - Segmental SNR and cepstral distortion tool
**conf_pns - PNS conformance tool
**conf_sbr - SBR conformance tool
*Create a set of NOSBRKITS like LPSBRKITS set and give them the parameters SBR=0 PARAMETRICSTEREO=0. Include mp4mcDec in this set. This can be used to decode AAC files without SBR to test the core decoder of on an HE-AAC file.

==Usage==

Run any tool with no arguments to see usage information.

====mp4mcDec====
mp4audec_mc [options] aacfile pcmfile

useful options:

-3 create 24-bit output files

-D<string> print out various bits of diagnostic info

Debug options:
v verbose
V show all tools used
N show frame numbers
h show header info
c debug channel coupling
f debug scalefactors
i debug intensity stereo
m debug mid/side stereo
p debug prediction
P debug PNS and pulse data
q debug quantization
r debug prediction resets
s debug sfb (scale factor band) information
R debug DRC (dynamic range control)
T debug TNS
w debug window sequences
x show DSE and FIL elements
X show DSE contents

===3GPP Reference implementation===
*HE-AAC Reference implementation http://www.3gpp.org/ftp/Specs/html-info/26410.htm

AAC Reference Software

2012-05-23T19:23:49Z

Zorglub21: /* 3GPP Reference implementation */

==Building==

===MPEG-4 Audio Reference Software===
*Latest Public Release http://standards.iso.org/ittf/PubliclyAvailableStandards/c050470__ISO_IEC_14496-5_2001_Amd_20_2009_Reference_Software.zip

===3GPP Reference implementation===
*HE-AAC Reference implementation http://www.3gpp.org/ftp/Specs/html-info/26410.htm

===Dependencies===
*AFsp: ftp://ftp.tnt.uni-hannover.de/pub/audio/AFsp/AFsp-v8r2.tar.gz
*Systems: http://standards.iso.org/ittf/PubliclyAvailableStandards/c045527_ISO_IEC_14496-5_2001_Amd_12_2007_Reference_Software.zip

The systems software appears to have at least one bug that makes it difficult to use it to mux various AAC formats to mp4. [http://lists.mpegif.org/pipermail/mp4-tech/2009-February/008672.html] A newer version is available at request from the [http://www.mp4ra.org MP4 Registration Authority] ([[Apple]])

===Build Process===
*The software is not 64-bit safe. On a 64-bit system "-m32" should be added to CFLAGS and LDFLAGS.
*Build AFsp and libisomediafile
*Set up environment variables in the make-all script
*Select "kits" to build, the important kits for AAC/HE-AAC decoding are:
**mp4mcDec - reference decoder and file format converter
**conf_ssnrcd - Segmental SNR and cepstral distortion tool
**conf_pns - PNS conformance tool
**conf_sbr - SBR conformance tool
*Create a set of NOSBRKITS like LPSBRKITS set and give them the parameters SBR=0 PARAMETRICSTEREO=0. Include mp4mcDec in this set. This can be used to decode AAC files without SBR to test the core decoder of on an HE-AAC file.

==Usage==

Run any tool with no arguments to see usage information.

====mp4mcDec====
mp4audec_mc [options] aacfile pcmfile

useful options:

-3 create 24-bit output files

-D<string> print out various bits of diagnostic info

Debug options:
v verbose
V show all tools used
N show frame numbers
h show header info
c debug channel coupling
f debug scalefactors
i debug intensity stereo
m debug mid/side stereo
p debug prediction
P debug PNS and pulse data
q debug quantization
r debug prediction resets
s debug sfb (scale factor band) information
R debug DRC (dynamic range control)
T debug TNS
w debug window sequences
x show DSE and FIL elements
X show DSE contents

AAC Reference Software

2012-05-23T19:23:17Z

Zorglub21: /* MPEG-4 Audio Reference Software */

==Building==

===MPEG-4 Audio Reference Software===
*Latest Public Release http://standards.iso.org/ittf/PubliclyAvailableStandards/c050470__ISO_IEC_14496-5_2001_Amd_20_2009_Reference_Software.zip

===3GPP Reference implementation===
*http://www.3gpp.org/ftp/Specs/html-info/26410.htm

===Dependencies===
*AFsp: ftp://ftp.tnt.uni-hannover.de/pub/audio/AFsp/AFsp-v8r2.tar.gz
*Systems: http://standards.iso.org/ittf/PubliclyAvailableStandards/c045527_ISO_IEC_14496-5_2001_Amd_12_2007_Reference_Software.zip

The systems software appears to have at least one bug that makes it difficult to use it to mux various AAC formats to mp4. [http://lists.mpegif.org/pipermail/mp4-tech/2009-February/008672.html] A newer version is available at request from the [http://www.mp4ra.org MP4 Registration Authority] ([[Apple]])

===Build Process===
*The software is not 64-bit safe. On a 64-bit system "-m32" should be added to CFLAGS and LDFLAGS.
*Build AFsp and libisomediafile
*Set up environment variables in the make-all script
*Select "kits" to build, the important kits for AAC/HE-AAC decoding are:
**mp4mcDec - reference decoder and file format converter
**conf_ssnrcd - Segmental SNR and cepstral distortion tool
**conf_pns - PNS conformance tool
**conf_sbr - SBR conformance tool
*Create a set of NOSBRKITS like LPSBRKITS set and give them the parameters SBR=0 PARAMETRICSTEREO=0. Include mp4mcDec in this set. This can be used to decode AAC files without SBR to test the core decoder of on an HE-AAC file.

==Usage==

Run any tool with no arguments to see usage information.

====mp4mcDec====
mp4audec_mc [options] aacfile pcmfile

useful options:

-3 create 24-bit output files

-D<string> print out various bits of diagnostic info

Debug options:
v verbose
V show all tools used
N show frame numbers
h show header info
c debug channel coupling
f debug scalefactors
i debug intensity stereo
m debug mid/side stereo
p debug prediction
P debug PNS and pulse data
q debug quantization
r debug prediction resets
s debug sfb (scale factor band) information
R debug DRC (dynamic range control)
T debug TNS
w debug window sequences
x show DSE and FIL elements
X show DSE contents

MP2

2012-05-23T18:57:50Z

Zorglub21:

* Codec ID: 0x0050

MPEG-1 Audio Layer II (MP2) is an audio codec defined by ISO/IEC 11172-3. An extension exists: MPEG-2 Layer II and is defined in ISO/IEC 13818-3. It is the predecessor of [[MP3]].

[http://www.cmis.csiro.au/maaate/docs/layer2.txt Some useful information on MPEG Layer 2] (unreachable as of Dec 7th 2007)

===Implementations===
*[http://sourceforge.net/projects/toolame/files/ TooLame], free software MPEG Layer II implementation with DAB support (Digital Audio Broadcasting)
*[http://www.twolame.org/ TwoLame], more recent free software implementation but DAB support broken

[[Category:Audio Codecs]]