[Ffmpeg-devel] Illegal instruction in ff_fdct_sse2 () from libavcodec.so.51

[Matthew Houliston]

Le mardi 18 juillet 2006 ? 14:58h, Guillaume Poirier 
<gpoirier at mplayerhq.hu> a ?crit :

 > Could you maybe try to compile and post the output of the attached
 > program?

root at www:~/cpuinfo# ./cpuinfo.out
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
stepping        : 3
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge 
mca cmov pat pse36 cflsh dts acpi mmx fxsr sse sse2 ss ht tm pbe pni 
monitor ds_cpl cid cx16 xtpr nx lm
cpu MHz         : 2800.161
model name      :                   Intel(R) Xeon(TM) CPU 2.80GHz


... which corroborates your theory that the CPU groks SSE but FreeBSD 
4.11 doesn't.



 > I don't know how this could be checked on runtime... it would be nice
 > if FFmpeg wouldn't crash... in such case, but I guess you've exposed a
 > bit of an unprobable corner case right there...

It probably doesn't need to be checked at runtime, only at compile time 
- which it is in a way, since configure gave me this message initially:

Error, no memalign() but SSE enabled, disable it or use 
--enable-memalign-hack.

Unfortunately --enable-memalign-hack doesn't resolve the problem in my 
case, and --disable-sse seems to be broken (or replaced by some new flag 
I don't know about?)

Again, thanks very much for the help, I appreciate it.