[vlc-devel] vlc segfault

Nikos Antonopoulos nantonop at orbitech.gr
Tue Dec 11 10:37:13 CET 2007


hi everyone,

i've been having a hard time locating the circumstances behind a vlc 
segmentation fault i've been having. The vlc scenario is that of 
"repeating" an x264/mp3 video stream through http and through the vlm 
web interface:

new TV1 broadcast enabled
setup TV1 input "http://remotehost:1234 :http:-caching=2048"
setup TV1 output #std{access=http,mux=asf,dst=localhost:1231}
control TV1 play

I'm running vlc 0.8.5 (have also tried 0.8.6c - same results) on Ubuntu 
Linux:
uname -a
Linux name 2.6.15-29-amd64-server #1 SMP Mon Sep 24 17:31:58 UTC 2007 
x86_64 GNU/Linux

The segfault occurs in random timeframes commonly in the course of 1-4 
days. The core dump refers to a violation regarding the p_peek buffer in 
the asf demuxer (in DemuxPacket()):

#0 Demux (p_demux=0xc27a60) at asf.c:411
#411 i_stream_number = p_peek[i_skip] & 0x7f;
(gdb) where
#0 Demux (p_demux=0xc27a60) at asf.c:411
#1 0x00000000004275e4 in MainLoop (p_input=0xea09b0) at input/input.c:526
#2 0x0000000000428d08 in Run (p_input=0xea09b0) at input/input.c:431
#3 0x00002aaaaacd00fa in start_thread () from /lib/libpthread.so.0
#4 0x00002aaaab2ebce2 in clone () from /lib/libc.so.6
#5 0x0000000000000000 in ?? ()

some more info...:

(gdb) info locals
i_payload_data_pos = 92
i_sub_payload_data_length = 2147483625
i_pts = 0
tk = (asf_track_t *) 0x0
i_stream_number = 0
i_media_object_offset = 0
i_replicated_data_length = 99
i_pts_delta = 1
p_peek = (uint8_t *) 0x2aaaafab52db 
"u\021C\035\036\224fN\016\207��%��R���c���\226}\017׳��\202*"
i_time_begin = <value optimized out>
i_result = <value optimized out>
p_sys = (demux_sys_t *) 0xda8fc0


It has been a handful trying to reproduce the effect. My estimation is 
that this occurs due to some sort of network issue which vlc handles 
badly. I understand p_peek is a direct pointer to p_buffer of the input 
module but can't seem to get my head round to why this may become 
corrupt and that point and after a couple days of running. i'm at a loss...

Any suggestions please? please let me know if i can provide more info on 
this.

many thnx
Nikos





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