Maybe this info will help someone in the future. It seems we have to be more careful with ffmpeg's ./configure with regard to CPU capability settings than we did in the past.
I had a strange problem with ffmpeg on an older K6-2 system after I upgraded it to a recent 2010-07-11 SVN snapshot of ffmpeg. The symptom was an "Illegal instruction" error whenever -s or -target was used. Using gdb, I was able to learn that ffmpeg's libswscale was calling the cpu instruction movntq which does not exist on the K6-2 (but does on the AMD Athlon and later). It turns out that the default ./configure resulted in: runtime cpu detection no yasm yes MMX enabled yes MMX2 enabled yes 3DNow! enabled yes 3DNow! extended enabled yes SSE enabled yes SSSE3 enabled yes CMOV enabled no CMOV is fast no EBX available yes EBP available yes but the K6-2 does not have MMX2, 3DNow! extended, SSE or SSSE3. The configure script only checks what the system can *compile*, not what the cpu can run. Furthermore, the run time cpu autodetect option (which increases the binary size a tad) is disabled by default. So, for older CPU's, ffmpeg will require additional options (that does not seem to have been needed in the past) as it will not run on them by default. In the case of the K6-2, these configure options are needed: --disable-amd3dnowext --disable-mmx2 --disable-sse --disable-ssse3 or perhaps instead: --enable-runtime-cpudetect but I did not test the latter approach. The ffmpeg developers may not consider this problem to be a bug, at least based on my reading of a past attempt to report something like this: https://roundup.ffmpeg.org/issue893 -- As a side note, there was also another issue in that there seems to be a circular dependency with libx264 and ffmpeg when invoking ffmpeg's: --enable-libx264 in that libx264 wants a recent version of ffmpeg's libraries before it will install. So, I installed ffmpeg without --enable-libx264, then libx264, then ffmpeg with --enable-libx264 to get around the catch 22. Cheers, Mike Shell -- http://linuxfromscratch.org/mailman/listinfo/blfs-support FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
