[vlc-devel] [vlc-commits] contrib: ffmpeg: add some cflags for arm/neon

[Rafaël Carré]

Le Sun, 27 Nov 2011 11:26:17 +0200,
"Rémi Denis-Courmont" <remi at remlab.net> a écrit :

> Le dimanche 27 novembre 2011 11:18:59 Rafaël Carré, vous avez écrit :
> > vlc | branch: master | Rafaël Carré <funman at videolan.org> | Sun Nov 27
> > 04:07:19 2011 -0500| [f625f16aa49ce21aec65f02993e02213a6ab31f6] |
> > committer: Rafaël Carré
> > 
> > contrib: ffmpeg: add some cflags for arm/neon
> > 
> > > http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=f625f16aa49ce21aec
> > > 65f02993e02213a6ab31f6
> > 
> > ---
> > 
> >  contrib/src/ffmpeg/rules.mak |    6 +++++-
> >  1 files changed, 5 insertions(+), 1 deletions(-)
> > 
> > diff --git a/contrib/src/ffmpeg/rules.mak b/contrib/src/ffmpeg/rules.mak
> > index 7622360..a4ca133 100644
> > --- a/contrib/src/ffmpeg/rules.mak
> > +++ b/contrib/src/ffmpeg/rules.mak
> > @@ -43,7 +43,11 @@ endif
> > 
> >  # ARM stuff
> >  ifeq ($(ARCH),arm)
> > -FFMPEGCONF += --disable-runtime-cpudetect
> > +FFMPEGCONF += --disable-runtime-cpudetect --arch=arm
> 
> This is pointless. FFmpeg can detect the architecture.

Somewhy, it did not and configure failed.

> If it did not, there 
> would be no point in disabling run-time detection in the first place.
> 
> > +ifdef HAVE_NEON
> > +FFMPEGCONF += --cpu=cortex-a8 --enable-neon
> 
> There are no reasons to hard-code the CPU. There are Cortex-A9 and proprietary 
> variants from ARM licensees too, and more are coming. Same goes for FPU.

so enable-neon should be enough?

> If you want to do this, set up your toolchain defaults correctly. Or then set 
> CFLAGS globally.
> 
> > +FFMPEG_CFLAGS +=-mfloat-abi=softfp -mfpu=neon
> 
> This will break systems using the VFP enhanced ABI. You should never change 
> the float ABI. This belongs in the toolchain defaults. Otherwise, your 
> binaries will not interoperate.
> 
> > +endif
> 
> Basically, I don't see any value in this commit.

honestly i just copy pasted this from extras/contrib, it seemed a bit
weird to me too that it set float-abi

-- 
Rafaël Carré