Re: [MPlayer-dev-eng] [PATCH] SSE2 optimizations for libmpeg2

[Alexander Strange <astrange@xxxxxxxxxxxx>]

On Apr 1, 2008, at 2:27 PM, Diego Biurrun wrote:
> On Tue, Mar 11, 2008 at 11:34:44AM +0800, Zuxy Meng wrote:
> > 2008/2/19, Diego Biurrun <diego@xxxxxxxxxx>:
> > > On Tue, Feb 19, 2008 at 09:41:52AM +0100, Diego Biurrun wrote:
> > > > On Sun, Feb 17, 2008 at 10:26:07AM -0700, Loren Merritt wrote:
> > > > > On Sat, 16 Feb 2008, Diego Biurrun wrote:
> > > > >
> > > > > > I found this patch on the libmpeg2 mailing list, here it is,  
> > > > > > slightly
> > > > > > adapted and cleaned up.  I could only test compilation without  
> > > > > > SSE2 as I
> > > > > > don't have a SSE2 processor.  I'd be happy to hear about test  
> > > > > > results
> > > > > > and benchmarks.
> > > > >
> > > > > Cpu detection is broken, attached patch fixes it (to be applied  
> > > > > on top of
> > > > > the previous patch).
> > > >
> > > > Here is an updated single patch that also fixes illegal  
> > > > identifiers and
> > > > includes some cosmetical changes.
> > >
> > > And here is a version without the (apparently ineffectual) motion
> > > compensation bits.
> >
> > Are u going to apply this?
>
> I'm not at all sure.  According to Christophe Massiot on libmpeg2- 
> devel
> the output of this IDCT differs from the MMXEXT one even though they  
> use
> the same algorithm.  Thus I'm not sure if it will ever be acceptable
> upstream.
>
> There must still be a bug lurking in there.  Maybe you can find it?
>
> Diego

This should be rounder_sse2 (0):
static const int32_t rounder4_128[] ATTR_ALIGN(16) = rounder (0);

Attached patch fixes that and builds with the last change to libmpeg2.

I noticed lavc's copy of this has ROW_SHIFT 11 instead of 15, but  
changing that here makes everything go purple. I'll leave that to  
someone else if they want more precision.

Attachment: libmpeg2_idct_patched.diff
Description: Binary data

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