Hi:
I am developing a SIP softphone frontend based on sipXtapi using Borland
Delphi. I met an Audio issue that someone had ever met again. I don't think the
issue solved throughly. I will provide my tests descriptions as follows.
My testing environment:
(1) Soft phones: sipXezphone (Version: sipXtapi 9605) & SJPhone(Version
1.60.289a)
(2) Network: 10M/100M Lan
(3) Client Hosts on wich Phones run: Pentium 4 3GHz / 1G Memory / SoundMAX
Integrated Didgital Audio
(4) SIP Server: OpenSER 1.2.0 (Same hardware configuration as the clients)
(5) Package Capture Tools: Ethereal
(6) Audio Codec: PCMA / PCMU
I made some groups of tests. Each group included 10 communication tests. I
would provide my findings as follows:
(1) Caller: sipXezphone
Callee: SJPhone
(2) SipXezphone would call SJPhone. Connection would cut off by SJPhone after
1 minutes each time. Repeat this step for 10 times.
(3) Nearlly at the 3rd or 4th time when SipXezphone calling SJPhone in each
testing group, audio crash would occur at the SJPhone side. (If I use
SipXezphone to SIpXezphone, audio crash would occur as well).
(4) I found that each time crash occured on SJphone, the following sequence
would occur (Showed by Ethereal).
SipXezphone OPENSer SJPhone
|<===============================>| RTP connection
|<------------------------|<-------------------------| Bye
|================================>| A RTP PCMU/PCMA package.
|------------------------>|------------------------->| 200 OK
Note : If I used mode of SJPhone 2 SJPhone, I found SJPhone would never send a
RTP package after receiveing a Bye message. Audio crash did not occur in
SJPhone to SJPhone mode.
I think SJPhone would use the wrong RTP package for decoding at the next
communication. So crash occured.
I think we should improve the following two aspects:
(1) Preventing sipXezphone from sending RTP package after receiveing a Bye
message.
(2) Enable sipXezphone to distinguish the error RTP package and do not use it
as the data input of decoding modules.
I have tried the improvement provided by the mail:
Re: [sipxtapi-dev] Only crash and noise heard with sipxtapi-media-updatebranch
(sent by Dieter on 16 Jan, 2007)
It seemed better, but crash did not disappear throughly. It would happen
sometimes. (The rate of occurrence is about 30%)
I don't know if I provide a clear description. Sorry for my basic English
writing.
Best, Feng XueSong
12 June, 2007
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