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Re: Audio/AMR

From: Noor Othman <nso01r@ecs.soton.ac.uk>
Date: Wed, 03 Jul 2002 16:45:01 +0100
Message-ID: <3D231BFD.6312AFA2@ecs.soton.ac.uk>
To: discuss@apps.ietf.org

>

Hello everyone,

    I have similar question, anyone knows where can I get AMR c-code? I have one from ITU website, but unfortunately, after
passing the codec, and decode them, it doesn't appear to be an audio file. Can't listen to it. Any advice much appreciated.

TQ

Noor


> Re: Audio/AMR
>
> From: Jeff Bouis (jbouis@lucent.com)
> Date: Mon, Apr 22 2002
>
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>    * In reply to: James Salsman: "Re: Audio/AMR"
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> Message-ID: <3CC44C77.68EC0FA8@lucent.com>
> Date: Mon, 22 Apr 2002 12:46:31 -0500
> From: Jeff Bouis <jbouis@lucent.com>
> To: James Salsman <james@bovik.org>
> CC: discuss@apps.ietf.org, vpim@lists.neystadt.org, jutta@pobox.com
> Subject: Re: Audio/AMR
>
> First was GSM 06.10 (full rate, or GSM-FR) at 13 kbps.  Later GSM 06.20
> appeared (half rate, or GSM-HR) at 5.6 kbps, and then came GSM 06.60
> (enhanced full rate, or GSM-EFR) at 12.2 kbps.
>
> Finally came GSM 06.90 (Adapative Multi-Rate, or GSM-AMR), at variable
> bitrates.  It encompasses 8 different birate modes, and some of those
> happen to be the same codec used in other systems:
>
>     12.20 kbps (GSM-EFR codec, and also TIA TDMA-US1 enhanced codec)
>     10.20 kbps
>      7.95 kpbs
>      7.40 kbps (TIA/EIA IS-641 TDMA EFR codec)
>      6.70 kpbs (PDC-EFR, or ARIB EFR codec)
>      5.90 kbps
>      5.15 kbps
>      4.75 kpbs
>
> Note that none of these are GSM 06.10, so to answer your question,
> Audio/AMR is NOT the same as GSM 06.10.
>
> UMTS also adopted AMR as its mandatory codec set.  The UMTS document set
> is virtually identical to the GSM set, and with regard to the codecs
> those changes are not significant.
>
> An introduction to the overall coding system is available as GSM 06.71.
> In particular, the codec itself is specified by GSM 06.90, source code
> is available in GSM 06.73, and test vectors in GSM 06.74.  (In the UMTS
> set, these correspond to 3GPP TS 26.071, 26.090, 26.073, and 26.074,
> respectively.)  All of these documents are available for free (after
> registration) from http://pda.etsi.org/pda
>
> Regards,
>
> Jeff
> jbouis@lucent.com
>
> James Salsman wrote:
> >
> > I have almost convinced myself that Audio/AMR is not the same as GSM 6.10
> > -- can anyone please confirm or deny this?
> >
> > Here is an Audio/AMR reference implementation for x86 PCs:
> >
> > http://www.3gpp.org/ftp/tsg_sa/WG4_CODEC/AMR-Wideband/AMR-WB_Characterization_Phase/Executables/g7221%26amrnb400_exe.zip
> >
> > Does anyone have source to an AMR codec?  I can't find it.
> >
> > > AMR is the mandatory format for voice message audio email attachments
> > > according to the MMS (Multimedia Messaging System) ETSI cellular
> > > telephone specification (ETSI 123 140), which incorporates the IETF MIME
> > > and VPIM specifications in large part.
> > >
> > > The MIME type registration for Audio/AMR is presently at:
> > >   http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-amr-13.txt
> > >
> > > The AMR specification is:  3GPP TS 26.101:
> > >   http://www.3gpp.org/ftp/tsg_sa/tsg_sa/TSGS_06/Docs/PDF/SP-99562.pdf
> >
> > Best wishes,
> > James
> > ----------------------------------------------------------
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>
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Received on Wednesday, 3 July 2002 13:11:30 GMT

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