Adaptive Multi-Rate audio codec: Difference between revisions

Revision as of 02:47, 17 November 2016

Revision as of 16:27, 22 November 2016

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{{Infobox file format

| name = Adaptive Multi-Rate (AMR)

| icon =

| logo =

| caption =

| extension = <tt>.amr</tt>, <tt>.3ga</tt><!-- Samsung Galaxy phones use .3ga -->

| mime = audio/amr, audio/3gpp, audio/3gpp2

| type code =

| uniform type =

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| latest release version = 9.0.0

| latest release date = {{Start date and age|2009|12|18|df=yes}}<!-- {{Start date and age|YYYY|mm|dd|df=yes}} -->

| genre = Audio compression format, [[audio file format]]

| container for =

| contained by =

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== Usage ==

The frames contain 160 samples and are 20 milliseconds long.<ref name="3gpp-26090" /> AMR uses various techniques, such as [[algebraic code excited linear prediction|ACELP]], [[discontinuous transmission|DTX]], [[voice activity detection|VAD]] and [[comfort noise|CNG]]. The usage of AMR requires optimized link adaptation that selects the best codec mode to meet the local radio channel and capacity requirements. If the radio conditions are bad, [[source coding]] is reduced and [[channel coding]] is increased. This improves the quality and robustness of the network connection while sacrificing some voice clarity. In the particular case of AMR this improvement is somewhere around S/N = 4-64–6&nbsp;dB for usable communication. The new intelligent system allows the network operator to prioritize capacity or quality per base station.

There are a total of 14 modes of the AMR codec, 8eight are available in a full rate channel (FR) and 6six on a half rate channel (HR).

{| class="wikitable"

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== Licensing and patent issues ==

AMR codecs incorporate several [[patent]]s of [[Nokia]], [[Ericsson]], [[Nippon Telegraph and Telephone|NTT]] and VoiceAge,<ref name="voiceage-amr_licterms">{{cite web |author=VoiceAge Corporation |publisher=VoiceAge Corporation |url=http://www.voiceage.com/amr_licterms.php |title=AMR Licensing Terms |date=2007-10-14 |accessdate=2009-09-12 |archiveurl=https://web.archive.org/web/20071014162046/http://www.voiceage.com/amr_licterms.php |archivedate=2007-10-14}}</ref><ref name="voiceage-amr_licterms2">{{cite web |author=VoiceAge Corporation |publisher=VoiceAge Corporation |url=http://www.voiceage.com/amr_licterms.php |title=AMR Licensing Terms |date=June 2007 |accessdate=2009-09-12}}</ref> the last one being the ''License Administrator'' for the AMR [[patent pool]]s. VoiceAge also accepts submission of patents for determination of their possible essentiality to these standards. However, it's very difficult to determine if there were actually any patents in existence for the so-called inventions related to AMR/AMR-WB codecs, since inventors (and their lawyers) do everything they can to hide patents related to AMR/AMR-WB technology{{Citation required|date=February 2016}}. Apparently, all these patents are hidden from all other researches and general audience that could perhaps spot prior art in the claimed "inventions" patented by the patent holders of the AMR/AMR-WB codecs.<ref name="voiceage-licpatentcalls">{{cite web |author=VoiceAge Corporation |publisher=VoiceAge Corporation |url=http://www.voiceage.com/licpatentcalls.php |title=Licensing - Patent Calls |date= |accessdate=2009-09-12}}</ref><ref name="archive-licpatentcalls">{{cite web |author=VoiceAge Corporation |publisher=Archive.org |url=http://www.voiceage.com/licpatentcalls.php |title=Licensing - Patent Calls |date=2007-10-14 |accessdate=2009-09-12 |archiveurl = https://web.archive.org/web/20071014161420/http://www.voiceage.com/licpatentcalls.php |archivedate = 2007-10-14}}</ref>

The initial fee for professional content creation tools and "real-time channel" products is US$6,500.{{When|date=November 2015}} The minimum annual royalty is $10,000, which, in the first year, excludes the initial fee. Per-channel license fees fall from $0.99 to $0.50 with volume, up to a maximum of $2 million annually.<ref name="voiceage-amr_licterms"/><ref name="voiceage-amr_licterms2"/>

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== Software support ==

* 3GPP TS 26.073 - {{snd}}AMR speech Codec (C source code) - {{snd}}reference implementation<ref>3GPP (2008-12-11) [http://www.3gpp.org/ftp/Specs/archive/26_series/26.073/26073-800.zip 3GPP TS 26.073 - AMR speech Codec], Retrieved 2009-09-08</ref>

* [[Audacity (audio editor)|Audacity]] (beta version 1.3) via the FFmpeg integration libraries<ref name="audacity-amr">Retrieved on 2010-02-28</ref> (both input and output format)

* [[FFmpeg]] with OpenCORE AMR libraries<ref name="ffmpeg-amr">[http://www.ffmpeg.org/general.html FFmpeg General Documentation - AMR external library], Retrieved on 2009-07-08</ref>

* [[Android (operating system)|Android]]<ref name="android-amr">[http://android.git.kernel.org/?p=platform/external/opencore.git;a=tree;f=codecs_v2/audio/gsm_amr;hb=HEAD Android AMR codecs], Retrieved on 2009-07-08 {{webarchive |url=https://web.archive.org/web/20090218232855/http://android.git.kernel.org/?p=platform/external/opencore.git;a=tree;f=codecs_v2/audio/gsm_amr;hb=HEAD |date=February 18, 2009 }}</ref> Used for voice recorder.

* [http://www.penguin.cz/~utx/amr AMR Codecs as Shared Libraries] - {{snd}}amrnb and amrwb libraries development site. These libraries are based on the reference implementation and were created to prevent embedding of possibly patented source code into many open source projects.

* Open source software to convert the .amr format: [http://sourceforge.net/projects/retrocode/ RetroCode], [http://sourceforge.net/projects/amr2wav/ Amr2Wav], both are in an early developmental stage

* [http://www.amrplayer.com/ AMR Player] is freeware to play AMR audio files, and can convert AMR from/to MP3/WAV audio format.

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* [http://media.io media.io] online conversion service (no need to install anything)

* [[MPlayer]] ([[SMPlayer]], <abbr title="Konqueror Media Player">KMPlayer</abbr><ref>[http://www.softadept.com/read/kmplayer-internal-audio-decoder-preferences-overview/ KMPlayer Internal Audio Decoder Preferences], Retrieved 2014-10-22</ref>)

* Parole Media Player 0.8.1 (in ubuntuUbuntu 16.04)

* [[QuickTime]] Player and multimedia framework

* [[RealPlayer]] version 11 and later

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* Apple [[iPhone]] (can play back AMR files)

* [[iOS]] & [[OS X]] (iMessage)

* [[BlackBerry]] smartphones (usesused for voice recorder file format)., OSwhile BB10[[BlackBerry 10]] cannot play AMR format.)

* [[K-Lite Codec Pack]]

* [[Media Player Classic Home Cinema#Media Player Classic - Home Cinema|Media Player Classic Home Cinema, around 1.7.1]]

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== See also ==

* [[Adaptive Multi-Rate Wideband]] (AMR-WB)

* [[Extended Adaptive Multi-Rate -– Wideband]] (AMR-WB+)

* [[Half Rate]]

* [[Full Rate]]

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== External links ==

* [http://www.3gpp.org/ftp/Specs/html-info/26090.htm 3GPP TS 26.090 - {{snd}}Mandatory Speech Codec speech processing functions; Adaptive Multi-Rate (AMR) speech codec; Transcoding functions]

* [http://www.3gpp.org/ftp/Specs/html-info/26071.htm 3GPP TS 26.071 - {{snd}}Mandatory Speech Codec speech processing functions; AMR Speech Codec; General Description]

* [http://www.3gpp.org/ftp/Specs/html-info/26-series.htm 3GPP codecs specifications; 3G and beyond / GSM, 26 series]

* RFC 4867 - {{snd}}RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs

* RFC 4281 - {{snd}}The Codecs Parameter for "Bucket" Media Types

{{Compression formats}}