Re: [mpeg2-dev] Fwd: segfault on bad pictures / low link power

[Keith W. <ke...@MI...>]

Hello İşbaran,

If you feed libmpeg2 bad data (e.g., if you're dropping packets and not 
replacing them), you will certainly see green blotches -- that's generally 
what you see when there's missing intraframe data.

(There are more sophisticated ways of doing error concealment in the 
presence of unreliable transport, but this is the basic behavior.)

You shouldn't be able to make libmpeg2 segfault, though -- it should 
simply detect the invalid elementary stream. Can you capture the exact 
data you're feeding into it (after the UDP reception) and find a 
replicable segfault? Then we can debug it. Otherwise, no offense, it's 
probably a bug in VLC. :-)

Best,
Keith

On Tue, 8 Sep 2009, İşbaran Akçayır wrote:

> Hello everyone,
>
> i've accidentally sent this message to vlc development list, redirecting 
> here cause i guess its related to libmpeg2
>
> -------- Original Message --------
> Subject: segfault on bad pictures / low link power
> Date: Tue, 08 Sep 2009 15:31:17 +0300
> From: İşbaran Akçayır <is...@gm...>
> To: Mailing list for VLC media player developers <vlc...@vi...>
>
> Hello,
>
> Since i dont know when trac is going online, i'm posting this here with
> all debug i could get.
>
> I'm using vlc in a udp rtsp multicast mpeg2 network, and this is what
> happens if link power is low, after some time (1-3 minutes)
> pictures/video are distorted with green mosaics.
>
> I can reproduce this with previous versions of vlc and current 1.0
> release. Tried on Pardus and Ubuntu Linux so far.
>
> here is gdb out:
>
> http://pastebin.com/f3a8493c
>
> I can produce any other information you need
>
> Best regards,
> işbaran
>
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