[Ffmpeg-devel] [PATCH] flacenc - lpc and options

Michael Niedermayer michaelni
Sat Jul 1 12:08:07 CEST 2006


On Fri, Jun 30, 2006 at 11:45:48PM -0400, Justin Ruggles wrote:
> Michael Niedermayer wrote:
> > [...]
> > a cleaned up md5.c is attached, iam not claiming it to be faster, probably
> > its not but that is a gcc issue, if gcc would unroll the main loop it would
> > be quite fast as everything could be optimized away
> > 
> > [...]
> In my standalone encoder, I was using a modified version of a pretty
> good public domain MD5 implementation.  I have added a couple more
> changes based on your code.  This is not a proposal for final inclusion,
> just another source for ideas.  It seems to run about 5X faster than
> what you posted, but like you said, that could just be a gcc issue.

hmm, ive added my code with some more changes into svn, the source
is almost half the size of your code and with CONFIG_SMALL it gets
compiled to ~2kb where your code is always >3kb, without CONFIG_SMALL
its still smaller then your code (all that only with 
gcc-4.1 -fomit-frame-pointer though, previous gcc had lots of troubble
with my code for some reason)
i didnt benchmark it but as the final code should be near identical it 
shouldnt be slower

furthermore i keep the struct in the c file and only export the size
so a user app wont by misstake mess with the internals and become
dependant on our implementation
also note we cant just *alloc() the struct in the init function as
libavutil should not depend on *malloc()


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is

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