I'm tracing the code to understand how it works. I'm not far enough but:

at main/translate.c the function "plc_fillin" is called. But there is no difference if i disable it. I'm in the end for now because of big complexity :-)

Martin Vít wrote:
Hello,

i've done some tests how the jitterbuffer works with SIP (asterisk 1.4b2) and tests shows that PLC is not working.

Configuration:

E1 Multiplexer with analog phone

Asterisk A:
E1 wcte11xp
version: 1.4b2

Asterisk B:
version: 1.2.11
ztdummy for timing

Simple testing method:

Call from analog phone via TDM -> E1 asterisk A -> SIP or IAX2 -> asterisk B (musiconhold)

testing codecs between asterisk A and B: alaw, g726


Jitter simulation:

asterisk B:
modprobe sch_netem
tc qdisc add dev eth0 root netem delay 0ms 0ms
tc qdisc change dev eth0 root netem delay 0ms 300ms

Results:

module reload codec_alaw shows that PLC is true.

Jitter is working for both IAX2 and SIP channels but without PLC.
I've switched back to 1.2.11 and IAX2 PLC was correct (for alaw chan_zap has to be patched to force codec to slinear, so transcoding can do PLC)
I've tried jitter buffer patch for 1.2 asterisk (from backports) and SIP PLC is not working too.

Sample audio:
Random Jitter (0-300ms) and correct PLC  http://www.lam.cz/iax2.wav
Random Jitter (0-300ms) without PLC http://www.lam.cz/sip.wav

So my question is: do i have something wrong or it is bug? Any suggestion will be appreciative.

Festr

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-- 
Martin Vít
LAM plus s.r.o.
http://www.vasesit.cz/
mobil: 605 267 610
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