Hi,
I agree with what you said partially. Because, in G.729 Annex E,
where the sampling frequency is 8 KHz, the LPC order is 30. Whys so?
Harshad.
> A complex pole for every KHZ in half the sampling
frequency and 2-4
> extra
> poles. So for CD quality sounds, with 22.1 KHZ we need about 23 cplx
> poles
> (46 order) + 4 extra poles = about 50.
Reply by ●May 7, 20022002-05-07
Here is a document that explains the derivation of no. of segments....
or the no. of LPC coeffs.....
-----Original Message-----
From: Harikrishna Natarajan [mailto:]
Sent: Monday, May 06, 2002 9:07 PM
To:
Subject: Re: [speechcoding] All pole LPC filter again
Hi
Great to have a good follow-up on an interesting topic. It would be great if
more who have good exposure to this topic, join in.
>All the reasonings given for 10th order LPC is
plausible. But i
>encountered
>50th order filter
>in G.728(LD-CELP). what could be the probable reason for having such a
>high
>order
>(computationally intensive) LPC in this codec.
>
>Note: The codec is a backward adaptive and uses 20 sample frame(2.5msec).
The choice of the order of the filter basically depends on the sampling
frequency (to bo more precise, half sampling frequency). Its usually taken
as follows:
A complex pole for every KHZ in half the sampling frequency and 2-4 extra
poles. So for CD quality sounds, with 22.1 KHZ we need about 23 cplx poles
(46 order) + 4 extra poles = about 50.
Any comments?
-Hari
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Reply by Harikrishna Natarajan●May 6, 20022002-05-06
Hi
Great to have a good follow-up on an interesting topic. It would be great if
more who have good exposure to this topic, join in.
>All the reasonings given for 10th order LPC is
plausible. But i
>encountered
>50th order filter
>in G.728(LD-CELP). what could be the probable reason for having such a
>high
>order
>(computationally intensive) LPC in this codec.
>
>Note: The codec is a backward adaptive and uses 20 sample frame(2.5msec).
The choice of the order of the filter basically depends on the sampling
frequency (to bo more precise, half sampling frequency). Its usually taken
as follows:
A complex pole for every KHZ in half the sampling frequency and 2-4 extra
poles. So for CD quality sounds, with 22.1 KHZ we need about 23 cplx poles
(46 order) + 4 extra poles = about 50.