Decoding AMR

Harald Welte laforge at gnumonks.org
Thu Feb 28 11:37:09 UTC 2013


Dear Akib,

I think it is best if you start to read the actual relevant GSM
specifications if you want to implement part of it.   The key word to
search for is probably the 'active code mode set'.

At any given point in time, there can only be a set of four active
codecs in an AMR connection.  The codec currently used within that set
is selected with CMI/CMR bits on the L1 of the air interface.   The
selection of which four codecs are part of the currently active set is
explicitly configured by signalling messages on RSL between BTS and BSC,
as well as on Layer3 (RR) between BSC and MS.

On Thu, Feb 28, 2013 at 01:15:37PM +0300, Akib Sayyed wrote:
> Dear Sylvain
> 
> 
> While Decoding AMR do need to just decode and pack it into raw amr frames
> or we need to think about hysterasis and all parts also
> 
> 
> also there are total 8 codec  modes
> 
> but in band data have details of on 4 codec modes
> 
> which one to choose out of 8 codec modes from those 8 modes.
> 
> 
> 
> 
> 
> 
> -- 
> Akib Sayyed
> Matrix-Shell
> akibsayyed at gmail.com
> akibsayyed at matrixshell.com
> Mob:- +91-966-514-2243

-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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