Hi Marko,
Repeat a decode with the last encoded packet. The decoder will then
interpolate internally to provide a smooth decoded speech output signal.
You could use packet n-1 or n+1 to replace missing packet n. I'd choose
the packet with the highest "energy" - in codec2.c you can see how the
energy is extracted from the bit stream for each mode.
I'm also wondering how strong is the dependency between subsequent encoded
packets? If there is a discontinuity due to packet loss will the decoder have
some period of instability or is each encode/decode pair independent?
OK what you mean is memory effects. Not much in most Codec 2 modes, as
we don't use predictive encoding of parameters much. For say 1300 and
700 bit/s modes, a bit error in frame n will only affect frame n+1.
IIRC think 1200 is the exception, as it has predictive coding of pitch
and energy,
- David
Thanks for your help,
Marko
-----Original Message-----
From: David Rowe <da...@rowetel.com>
Sent: April 11, 2018 3:39 PM
To: freetel-codec2@lists.sourceforge.net
Subject: Re: [Freetel-codec2] Codec2 and packet loss
Hi Marko,
Just repeat the last (or maybe next) packet. My tests indicate a PER of 10% to
be the limit for useful speech quality.
- David
On 12/04/18 06:46, Marko Milutinovic wrote:
Hello,
What is the best way to deal with packet loss when using Codec2? For
example if I send out 10 (1-10) packets and on the receiving side I
get
1,6,7,8,9 (after buffering) what would be the best way to minimize noise?
Do I just sequentially decode the packets I have received and plug in
NULL audio in between or is there something else that can be done to
interpolate?
Thanks,
Marko
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