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Re: [codec] WG Review: Internet Wideband Audio Codec (codec)

"Ingemar Johansson S" <ingemar.s.johansson@ericsson.com> Tue, 12 January 2010 10:00 UTC

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From: Ingemar Johansson S <ingemar.s.johansson@ericsson.com>
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Subject: Re: [codec] WG Review: Internet Wideband Audio Codec (codec)
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Hi Christian and others

Timescaling and jitter buffer management is AFAIK not included in the codec specifications done in other standards foras. But that does not mean that it is left unspecified. In 3GPP TS we settled with a specification of only the requirements
http://www.3gpp.org/ftp/Specs/archive/26_series/26.114/26114-910.zip 
There are many reasons to why we did this, one is that we regard time scaling as yet another pre/post processing algo like packet loss concealment, echo cancellation or noise suppression, and the hard cold truth is that the less one need to specify in terms of code so much the better (go figure..). We needed however to set some requirements however to avoid poor implementations. 

With the above in mind I would claim that it is wrong to state that the answer to statement 2) below is a NO.

/Ingemar 


From: "Christian Hoene" <hoene at uni-tuebingen.de> 
To: "'Xavier Marjou'" <xavier.marjou at orange-ftgroup.com> 
Cc: 'IAB IAB' <iab at iab.org>, codec at ietf.org, 'IETF Discussion' <ietf at ietf.org>, 'IESG IESG' <iesg at ietf.org> 
Date: Tue, 12 Jan 2010 01:27:43 +0100 
In-reply-to: <458913681001111218o3b232e4sd785b3c09809fcbc at mail.gmail.com> 
References: <20091223171501.7BAE33A697D at core3.amsl.com> <13194D66-2110-4CB2-B130-8807BE57488B at cisco.com> <458913681001111218o3b232e4sd785b3c09809fcbc at mail.gmail.com> 

--------------------------------------------------------------------------------

Snip snip...

> Therefore, the 3 stages mentionned are essential to be run
> sequentially:
> "(1) get consensus on the requirements, (2) see if an existing codec
> meets the requirements, and (3) specify a new codec only if none are
> found in stage 2. Initially the WG would be chartered for (1) and when
> that was done it would be re-charted for (2) and so on. "

Obviously, the current requirements document does contain features which are
not supported by today's standardized codecs. As an example, take time
stretching and time compression. Thus, everybody following the discussion
must come to the conclusion that (2) has been answered with no. 



=================================
INGEMAR JOHANSSON  M.Sc. 
Senior Research Engineer 

Ericsson AB
Multimedia Technologies
Labratoriegränd 11
971 28, Luleå, Sweden
Phone +46-1071 43042
SMS/MMS +46-73 078 3289
ingemar.s.johansson@ericsson.com
www.ericsson.com 
Visit http://labs.ericsson.com !
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