[Live-devel] Unhandled exception during TEARDOWN

[Erlandsson, Claes P (CERLANDS)]

The crashes are very consistent. Not the frequency, but the location. When
they occur, 602 is always the last message printed. I've attached an output
example. Judging by the callstack it almost looks to me like the printf
would be the cause, but the same thing happens if I remove the debug output,
i.e. 602, and 601 etc.

 

This however makes no sense at all. What is causing the sudden app crash? I
see no explanation at all in the code.

 

I suspect that a 'memory smash' - i.e., a write through a bad pointer
(caused by a bug in the code) - is to blame.  If that happens, then a
pointer somewhere else might be getting corrupted, which could lead to an
error like this that occurs in an unexpected place in the code.

 

I suggest that you run a 'memory debugger' on your application.  See

            http://en.wikipedia.org/wiki/Memory_debugger

 

Some tools that I've seen recommended are

- "Dr. Memory":          http://code.google.com/p/drmemory/

- "OllyDbg":                http://ollydbg.de/

 

Thanks. Never heard of those two, but will look into.





I would also suspect threads going havoc, but as liveMedia is
single-threaded that shouldn't be the case.

 

Correct - provided, of course, that your *application* uses only a single
thread (that calls LIVE555 code).

 

Well, "our app" uses multiple threads outside the liveMedia library, but
I've lately only been testing with the modified testRTSPClient that I
attached.





It definitely seems like the server matters. How can that be?

 

Perhaps it's because the different servers (streams) use different codecs
(and thus our RTSP client code uses different classes to receive/process the
incoming packets)?

 

I see (from the SDP descriptions returned in response to "DESCRIBE") that
the stream(s) that are causing your crash are using motion JPEG.  What about
the "Axis 243q" streams (the ones that you think do not cause the crash)?
What codec do they use?  (Please post a SDP description from those streams.)

 

That makes sense. I was planning on setting up some Cisco VMS streams using
mpeg4, but wasn't sure how/if that affected the client. The Axis 243q always
outputs mpeg4 while using rtsp. I've attached output from Axis 243q
mpeg4-streams which includes the SDP. Now when you point it out it seems
fairly safe to say jpeg is the source of the issue.

 

btw. I know you discourage mjpeg, and I can agree on that, but there are
legacy reasons for us still using it and bandwidth isn't an issue in our
case.

 

Thanks!

 

/Claes

 

 

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/ 

 

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