[theora] olpc theora-svn testing

Vasilis Liaskovitis vliaskov at gmail.com
Tue Feb 5 07:23:07 PST 2008


I have done a simple libtheora test for the theora ticket
(http://dev.laptop.org/attachment/ticket/5988/), using theora-svn. The
results are at:

For the sake of discussion here, 've copied some comments from the
results section on the wiki:

- the patch for super fastmode seems to give an impressive speedup.
Depending on video input, encoding time is reduced by 33%-55% for the
default or the cc4.3-geode library.
- the gcc4.3 geode-aware configuration/compilation does not seem to
provide performance gains against the default libtheora. In fact the
default libtheora seems to be slightly faster for the superfast
encoder mode - do we know the configuration/compiler flags used? Many
performance critical routines seem to be hand-coded assembly. Are
there important routines that the compiler affects? Any other compiler
flag suggestions are welcome.
- disabling mmx has a big performance hit as expected.

- Do we have specific encoding timing restraints for videoconferencing
- Can anyone suggest suitable inputs that combine both video and audio?

I have not used the gnashdev gcc4.3 build
(http://wiki.gnashdev.org/wiki/index.php/Building_OLPC_Tools), but my
own build. Let me know if something seems to be missing from the

configured with: /home/vliaskov/compilers/gcc-geode/gcc/configure
--prefix=/opt/gcc4-3-gode --enable-shared --enable-threads-posix
--with-systen-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-languages=c,c++ --disable-dssi
Thread model: posix
gcc version 4.3.0 20080116 (experimental) (GCC)

If something seems wrong in my gcc4.3 build, let me know


- Vasilis

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