[FFmpeg-devel] MPEG-2 Acceleration Refactor

[Michael Niedermayer]

Hi

On Fri, Jun 22, 2007 at 07:01:35PM +0200, Michael Niedermayer wrote:
> Hi
> 
> On Fri, Jun 22, 2007 at 09:39:00AM -0700, Greg Hulands wrote:
> > Hi,
> > On 22/06/2007, at 5:59 AM, Ivan Kalvachev wrote:
> > 
> > > 2007/6/22, Michael Niedermayer <michaelni at gmx.at>:
> > > [...]
> > >>
> > >> i am not saying how to solve this, the original intent was some  
> > >> hardware
> > >> acceleration support for mpeg1/2 with specific hardware _IIRC_,  
> > >> iam just
> > >>
> > >> saying how not to do it, which is
> > >> * no slowdown for the normal case
> > >> * no messy code which also means not replacing large functions by  
> > >> large
> > >>   macros
> > >
> > > How about placing the new code under #ifdef HAVE_XVMC #endif and not
> > > bother refactoring the coefficient reading functions at all?
> > > In normal case it would not be defined, in other case hw acceleration
> > > would be used and it should be way faster:)
> > > Afaik they are going to do their own version of the key xvmc  
> > > functions.
> > 
> > When Nigel first submitted the original patch that was how it was  
> > done, but Michael had said it won't be accepted unless there was a  
> > refactor of those methods. That is what this patch is for. But if it  
> > is now considered not to be the best route is it going to be okay to  
> > have the #idefs? I hope it is otherwise it is going to leave this at  
> > an impasse.
> 
> nigels patch adds 34 #ifdefs to mpeg12.c
> 2 of them being #ifdef __cplusplus
> 
> XVMC has currently 7 #ifdefs in mpeg12.c

now its just 6 ...

decrease the number of ifdefs of nigels patch to <=6 with no code duplication
and no slowdown for the normal case and it has some chance to reach svn but
with 34 ifdefs or slowdown due to gcc bugs it does not

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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