[FFmpeg-devel] [PATCH][RFC] Lagarith Decoder.

Michael Niedermayer michaelni
Wed Aug 12 21:42:42 CEST 2009


On Wed, Aug 12, 2009 at 08:25:41PM +0100, M?ns Rullg?rd wrote:
> Michael Niedermayer <michaelni at gmx.at> writes:
> 
> > On Wed, Aug 12, 2009 at 07:47:45PM +0100, M?ns Rullg?rd wrote:
> >> Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
> >> 
> >> > On Wed, Aug 12, 2009 at 06:59:42PM +0100, M?ns Rullg?rd wrote:
> >> >> Michael Niedermayer <michaelni at gmx.at> writes:
> >> >> 
> >> >> > On Wed, Aug 12, 2009 at 06:31:36PM +0200, Reimar D?ffinger wrote:
> >> >> >> On Wed, Aug 12, 2009 at 05:10:36PM +0100, M?ns Rullg?rd wrote:
> >> >> >> > Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
> >> >> >> > 
> >> >> >> > > On Wed, Aug 12, 2009 at 04:12:25PM +0100, M?ns Rullg?rd wrote:
> >> >> >> > >> Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
> >> >> >> > >> 
> >> >> >> > >> > Well, you still have to teach the compiler at least to
> >> >> >> > >> > use clz for av_log2, I think you haven't yet ;-)
> >> >> >> > >> 
> >> >> >> > >> I can't because it's in common.h, which is installed.  We really
> >> >> >> > >> should find a way to fix that.
> >> >> >> > >
> >> >> >> > > Just put the optimizations under HAVE_AV_CONFIG_H like
> >> >> >> > > everything else in there that is messy?
> >> >> >> > 
> >> >> >> > And keep adding to the mess?  That's not the way to do things.
> >> >> >> 
> >> >> >> Then how about adding a new internal header with that function and
> >> >> >> putting the version in the installed header under
> >> >> >> #ifndef HAVE_AV_CONFIG_H
> >> >> >> i.e. just to keep API compatibility?
> >> >> >> Possibly even deprecating that version?
> >> >> >> Would that be clean enough?
> >> >> >
> >> >> > It would be nice if applications using libav* could also use
> >> >> > the optimized version
> >> >> 
> >> >> I can't see a way to make that happen.
> >> >
> >> > Actually... You could install a pseudo-config.h that contains the
> >> > necessary CPU settings...
> >> > There is not really a reason we can't install generated headers...
> >> > Or am I missing something?
> >> 
> >> Doing so would require all FFmpeg-using apps to use the same compiler
> >> and flags as were used when configuring FFmpeg.  This is not
> >> reasonable.
> >
> > a few #ifdefs in the header would solve that,
> > same compiler -> all optims
> > other compiler -> fallback to plain C
> 
> That is not very nice.  Besides, it is impossible to implement.

could you elaborate on why it is impossible?

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Why not whip the teacher when the pupil misbehaves? -- Diogenes of Sinope
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