[MPlayer-dev-eng] [RFC] rc2

[Zuxy Meng]

Hi,

2007/4/9, Arpi <arpi at thot.banki.hu>:
> Hi,
>
> > theres nothing lavc specific here, SSE* code needs aligned data outside
> > lavc too
> >
> >
> > > (win only?
> >
> > > can it happen with mplayer?)
> >
> > if (gcc doesnt maintain alignment || main or another entry point like thread
> > stuff is called with missalged stack && gcc doesnt align the stack) && the
> > stack is used for something which needs proper alignment
> >
> > the gcc behavior depends on version and flags given to it (and no i dont know
> > the details RTFgccM )
>
> it was (and probably still is) a problem with mingw32-compiled win32
> mplayer binaries. cygwin has no problem, it uses own memory allocator,
> but mingw relies on windows' memory functions which has no memalign() :(
>
> there was 2 ideas to solve this, one is using some 3rd-party memory library
> when compiling with mingw, the other is changing all the code (mostly in
> libavcodec) which needs alignment to do the alignment for itself, like:
>  buffer1_base=malloc(buffer1_size+15);
>  buffer1=(buffer1_base+15)&(~15);
> but it's quite ugly and hackish, and as only win32/mingw needs it nobody
> would support it...   the workaround is/was to disable sse in mingw builds :(

FFmpeg uses its own routine to detect CPU capabilities at runtime so
SSE can't be completely disabled unless something is also done from
ffmpeg's side.
-- 
Zuxy
Beauty is truth,
While truth is beauty.
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