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

Måns Rullgård mans
Wed Aug 12 21:25:41 CEST 2009


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.

-- 
M?ns Rullg?rd
mans at mansr.com



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