[FFmpeg-devel] dealing with tables in DV codec

Michael Niedermayer michaelni
Wed Sep 10 17:35:31 CEST 2008

On Wed, Sep 10, 2008 at 03:51:27PM +0200, Diego Biurrun wrote:
> On Tue, Sep 09, 2008 at 01:51:06PM -0700, Roman Shaposhnik wrote:
> > 
> > Now, on SPARC I see a stable speed loss of about ~3% or so.
> While we're discussing performance: qdv still performs about 50% better
> than FFmpeg on certain samples, do you know the reason?  An example is
> http://samples.mplayerhq.hu/V-codecs/DVSD/henrich-weirdqt.mov

I cant say anything about this file as ive not looked at it, but dv renders
macroblocks in a random order that could be rather hard on the cpu caches.

as ive already sugested to roman but have not heared a awnser for yet is
to try to replace movq by movntq in put_pixels_clamped_mmx() and check
that thats also used. It would be interresting to know if that has
any effect on speed.
Also changing the decoder to decode MBs in a less random order would likely
lead to large speed gains.


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The educated differ from the uneducated as much as the living from the
dead. -- Aristotle 
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