[M4IF Technotes] What does AMR stand for? / Where's CELP

[Bruce Schulman]

Alain,
Is AMR used in GSM?  I don't think it was useful until 2.5G or 3G.  So,
would it be the case that "adaptive" bit rate is only useful in certain
types of mobile communications - like packet based networks or CDMA and not
TDMA networks.
Bruce Schulman
============
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-----Original Message-----
From: technotes-admin   lists.m4if.org
[mailto:technotes-admin   lists.m4if.org]On Behalf Of Alain Tritschler
Sent: Friday, March 14, 2024 3:19 AM
To: Ralph Neff; Technotes   lists.m4if.org
Cc: 'Ben Waggoner'
Subject: RE: [M4IF Technotes] What does AMR stand for? / Where's CELP
> Regarding CELP, my interpretation is that low
> bitrate speech codecs are most useful in the mobile
> space, due to the low bandwidth and the fact that
> 2-way speech communication is a core application.
> But MPEG-4 CELP isn't specified by any of the mobile
> standards (e.g. 3GPP, 3GPP2).

My understanding is that AMR has a great advantage over CELP for mobile
communications, which is that it is _adaptive_ : CELP allows a constant
bitrate while it is possible to adapt the audio bitrate of AMR to network
conditions.
Also, the AMR codec implementation (normalized in both the encoder and
decoder) is very efficient, while CELP (in the VM) is significantly slower.
> Sure it's in ISMA, but the target application for
> ISMA (one-way multimedia delivery, wide range of content,
> transport via internet) makes generic audio coding
> (AAC) much more interesting/useful than speech coding.
>
> -Ralph
>
>
> -----Original Message-----
> From: Ben Waggoner [mailto:ben   interframemedia.com]
> Sent: Thursday, March 13, 2024 2:36 PM
> To: Technotes   lists.m4if.org
> Subject: [M4IF Technotes] What does AMR stand for? / Where's CELP
>
>
> Folks,
>
>     I know I should know this, but don't seem to.  What does the
> AMR acronym
> actually stand for?
>
>     Also, anyone have a good story for why CELP audio
> implementations are so
> rare, even though the codec is part of ISMA?
>
>
> Ben Waggoner <http://www.benwaggoner.com>
> Compressed Video Consulting, Training, and Encoding
>
> My Book:            <http://www.benwaggoner.com/books.htm>
> Cleaner e-book:     <http://www.cmpbooks.com/cleaner>
>
> Compression Classes at Stanford  June 30-July 4 and Aug 11-15
> <http://www.digitalmediaacademy.org/compression.html>
>
>
>
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