Forums

AMR codec (ETSI version v.s. 3GPP version)

Started by Murphy Chen January 9, 2004
ETSI has a AMR reference code.
3GPP also has AMR reference code for both fix-point and floating
point.

What's the difference between them?
Which version is preferred?



Hi Murphy,
There is no algorithmic difference btw ETSI AMR and
3GPP AMR. 3GPP AMR support packing of coded bits and
unpacking of bits before decoding. This packing and
unpaking is done as per RFC3267.
There is difference between these two versions of AMR
for DTX mode.
In ETSI amr for DTX ON, 245th word in coded bit stream
is alway value of mode i.e. from 0 to 8, where 8 for
DTX mode.
In 3GPP AMR for DTX ON, 245th word is value of mode
for non DTX frame but it is equal to -1, if DTX frame
is found.
Hence for NON DTX test streams there is no diff. in
ETSI and unpacked bit stream. But for DTX bit stream
only 245th word of DTX frame is different. Snehal --- Murphy Chen <> wrote:
> ETSI has a AMR reference code.
> 3GPP also has AMR reference code for both fix-point
> and floating
> point.
>
> What's the difference between them?
> Which version is preferred? >


__________________________________



Hi all

can anyone of you tell me where I can get codes for
LPC-10 algorithm written in Matlab,C,C++
or the compact algorithm for this.
Please send me the links and if u have LPC-10 codes
written in any language send me.
Thanks

Regards
Devi Lal Sharma =====
Devi Lal Sharma #143,Ganga Hostel
3/5 Dual Degree IIT Chennai-36,India
Stream:Communication Ph: +91-44-22579073,8917
Deptt.:Electrical Engg.
IIT MADRAS (INDIA)
email:,

__________________________________


Another diffrence.. In ETSI one flag called NSYNC is used as input from
the n/w. Where as in 3GPP this is not used. The NSYNC is used in mobile
communication when switching from one Base station to next base station.
This alter the VAD operation. When ever NSYNC is set, the mode will not be
NODTX.
Regards
---
Shivanand Hiremath
----

On Thu, 29 Jan 2004, snehal joshi wrote:

> Hi Murphy,
> There is no algorithmic difference btw ETSI AMR and
> 3GPP AMR. 3GPP AMR support packing of coded bits and
> unpacking of bits before decoding. This packing and
> unpaking is done as per RFC3267.
> There is difference between these two versions of AMR
> for DTX mode.
> In ETSI amr for DTX ON, 245th word in coded bit stream
> is alway value of mode i.e. from 0 to 8, where 8 for
> DTX mode.
> In 3GPP AMR for DTX ON, 245th word is value of mode
> for non DTX frame but it is equal to -1, if DTX frame
> is found.
> Hence for NON DTX test streams there is no diff. in
> ETSI and unpacked bit stream. But for DTX bit stream
> only 245th word of DTX frame is different. > Snehal > --- Murphy Chen <> wrote:
> > ETSI has a AMR reference code.
> > 3GPP also has AMR reference code for both fix-point
> > and floating
> > point.
> >
> > What's the difference between them?
> > Which version is preferred?
> >
> >
> > __________________________________ > _____________________________________
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