hi Subrata!
i can try to answer the last 2 queries..
query 3.
LPC coefficients are the coeffts of the SYNTHESIS
filter. Since they are not suitable for direct
quantisation,they are converted to LSP coeffts to
guarantee the stability of reconstruction filter at
the receiver end.
now, once u get the LSP coeffts at the decoder, u need
to convert them back to LPC coefficients again because
that's how u will have a synthesis filter to
reconstruct the original speech.
query 4:
the best way to find out which functions take the max
time and contribute heavily in terms of MIPS is to
PROFILE the code... do this for all the test vectors.
this feature is available in VC and also in any other
processor's simulator/cross compiler.(the only problem
is that it is a very time consuming business... u will
find out soon!)
Sameer.
--- subrata_etc <> wrote: > hi
friends,
> I have just started working with AMR speech
codec.
> I
> would like post few general queries which are
> written
> below....
> 1)What is the application of different bit
> rates(12.2,10.2,7.95,7.40,6.70,5.90,5.15,4.75
> kbits/sec in practical field?
>
> 2)After using the auto-correlation why we are using
> lagging window??
>
> 3)By using Levinson- Durbin algorithm we are
> transforming the coefficients into LP filter
> coefficients. Then These LP filter coefficients are
> transformed into LSP coefficients. But why do we
> need
> to transform back the LSP filter coefficients into
> LP
> filter coefficients?
>
> 4) What are the major functions in the standard AMR
> encoder which effect the MIPS rating of the
> encoder??
> Anyone experienced in this field please let me know
> the answers of the above queries.
> Thanks in advance
>
> bye
> Subrata Chatterjee
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