[Freeswitch-users] autofix incorrect packetization

[Hristo Trendev]

Hi,

I get choppy audio in conferences from endpoints that send
G722 at 30mspackets. The endpoint in question is a FRITZ!Box CPE and this
seems to be a
known problem with these type of devices. They simply ignore the offered
ptime in SDP and stick to sending 30ms RTP packets no matter what.

The last time I tested with a FRITZ!Box CPE was in February and I am
absolutely sure that FS used to auto fix this type of problems in the past
and when this was happening I would see the following lines in the logs:

"Asynchronous PTIME not supported, changing our end from 20 to 30"
"Changing Codec from G722 at 20ms@8000hz to G722 at 30ms@8000hz"
and also something to do with timer resolution being increased to deal with
30ms intervals.

This doesn't happen any more  (v1.2.14) and all I can hear is choppy audio
from these CPEs. The only relevant lines I could find in the logs were:

"mod_conference.c:3590 Setup timer soft success interval: 20  samples: 160"
"switch_core_io.c:759 Engaging Read Buffer at 640 bytes vs 240"

I also verified with a packet trace that FS is indeed receiving RTP packets
with payload of 240 bytes, which would correspond to 30ms and is sending
packets with 160 bytes of payload (20ms), so as far as I can tell this
would actually classify as async ptime.

I only see the problem one way - the choppy audio comes from the remote
party, which is sending the 30ms packets into the conference. The remote
party however still hears normal audio coming from the conference (although
it is packetized and sent out at 20ms). Could it be that for some reason FS
or the conference application is mistakenly treating the 30ms packets as
20ms ones when mixing the audio into the conference?

I do recognize that this is caused by misbehaving end device and it is not
a FS issue, but I just wanted to know if someone else is also seeing
similar problems or if this can somehow be related to a recent change in
the FS code? I have updated to v1.2.15 so I can retest, but I will only get
a chance to do it on Friday.

Best
Hristo
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