Decoding AMR

Akib Sayyed akibsayyed at gmail.com
Thu Feb 28 14:54:27 UTC 2013


Thanks for Quick response.

I tried studying TSM code layer1 and Osmocom layer1 for purpose of
implementing them in cellphone it self but i as far as i know that init of
some variables required for amr are completed  but couldnt be able to
figure out what exactly part remaining .

also for decoding AMR convolution i made some changes to structures given
by sylvain. I didnt know what i was doing but gave me correct output for
encoding and decoding. but still i doubt its correctness. It would be great
if some one could comment on these files.



may be need to pay attention soon
On Thu, Feb 28, 2013 at 2:37 PM, Harald Welte <laforge at gnumonks.org> wrote:

> 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'.
>
> I will try to check specs again. i am really doubting about hysteresis
part. cause i dont know whether its needed or not while storing raw frames.
if any one know please let me know shall save my time.


> 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.

thanks for pointing out.

>   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/
>
> ============================================================================
> "Privacy in residential applications is a desirable marketing option."
>                                                   (ETSI EN 300 175-7 Ch.
> A6)
>



-- 
Akib Sayyed
Matrix-Shell
akibsayyed at gmail.com
akibsayyed at matrixshell.com
Mob:- +91-966-514-2243
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