[FFmpeg-devel] [HOWTO] Building FFmpeg for iPhone
Sat Oct 3 19:29:58 CEST 2009
On Sat, Oct 03, 2009 at 07:23:46PM +0200, Reimar D?ffinger wrote:
> On Sat, Oct 03, 2009 at 07:03:00PM +0200, Reimar D?ffinger wrote:
> > On Fri, Oct 02, 2009 at 11:05:43PM +0100, M?ns Rullg?rd wrote:
> > > "Ronald S. Bultje" <rsbultje at gmail.com> writes:
> > > >> 4a. For iPhone 3GS or iPod Touch 3G 32GB/64GB, use this command:
> > > >> 4b. For other iPhone or iPod Touch models, use this command:
> > > >
> > > > What if I want one that is cross-compatible with both?
> > >
> > > Binaries for the old devices will work on the new ones. However,
> > > FFmpeg will be *much* faster if built for the 3GS since it supports
> > > NEON.
> > Is there some way to do runtime detection of NEON?
> Seems like ARM is one of those instructions sets that didn't consider it
> necessary to include a (userspace-)instruction for this.
> With the usual effect of making runtime detection a broken mess.
> I hereby declare my very firm wish that anyone who designs an instruction
> will in the future also try to make it practical to use also for those
> who care about backwards compatibility.
MIPS is funnier. There are at least 3 SIMD instructions sets I've heard
of and no way of detecting them since they all just standard calls to
co-processor 1 or 2.
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