On Mon, Jul 23, 2012 at 05:37:33PM -0700, Daniel Kang wrote:
> On Mon, Jul 23, 2012 at 5:21 PM, Diego Biurrun <[email protected]> wrote:
> > On Mon, Jul 23, 2012 at 05:12:23PM -0700, Daniel Kang wrote:
> > > From: Daniel Kang <[email protected]>
> > >
> > > The only CPUs that have 3dnow and don't have mmxext are 12 years old.
> > > ---
> > >  libavcodec/x86/dsputil_mmx.c   |    9 ---------
> > >  libavcodec/x86/h264_qpel_mmx.c |    4 ----
> > >  2 files changed, 0 insertions(+), 13 deletions(-)
> >
> > What sort of maintenance burden does this relieve us from?
> > I'm writing this mail on a system fitting the description
> > you mention, my trusty old K6-III.
> 
> 1. Decreases binary size.

How much?

> 2. We don't support Windows ME (12 years old), I don't see a reason to keep
> this cruft.

There is no reason to throw away perfectly working computers.  Not
everybody lives in a rich country, actually, most people don't.

> 3. 3dnow becomes a pain when I'm trying to port code to yasm.

So let's talk again when those patches are ready.

> 4. You can probably decode 260p H.264 with a K6-III. Who seriously would
> use this?

This works for example:

  http://samples.libav.org/V-codecs/h264/cathedral-beta2-400extra-crop-avc.mp4

  Stream #0.2(eng): Video: h264 (Main), yuv420p, 640x352, 401 kb/s, 23.98 fps, 
23.98 tbr, 2997 tbn, 23.98 tbc
  Stream #0.3(eng): Audio: aac, 44100 Hz, stereo, s16, 95 kb/s

The killer in that case is the AAC audio track.  It uses one of the
trillion profiles/options that AAC has and exchanges 1% compression
gain for 500% decoding load increase.  Switch to MP3 and you're fine.

Diego
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