[FFmpeg-devel] [RFC] use get_unary in multiple places

Michael Niedermayer michaelni
Mon Aug 13 18:47:53 CEST 2007


On Mon, Aug 13, 2007 at 03:27:01PM +0200, Vitor Sessak wrote:
> Hi
> Alex Beregszaszi wrote:
> > Hi,
> > 
> > the following patches make use of get_unary at all possible places I
> > found.
> > 
> > Patches in order:
> > 
> > 1, alac: use get_unary where appropriate.
> > 
> I know I risk to ressurect a flamewar, but Michael, could you review the 
> two alac patches? 

see https://roundup.mplayerhq.hu/roundup/ffmpeg/issue93

> I didn't benchmark the decoding time before and after 
> the change, but since use_unary could use some high level optimizations 
> (enable the code using av_log2) I think it should be done before doing 
> low level ones. 

the first thing needed is to not use get_unary() directly because its bloated
and silly  API forces the compiler either
A. to inline the function everywhere and then optimize the unneeded cases
   out (more inlining is not neccessarily good, in the h.264 code for example
   it leads to significant slowdown due to the main loop becoming larger than
   the code cache)
B. to pass unneeded parameters (more and slower code) to get_unary() which
   then does unneeded computations

the solution is described in issue93 ...

> Btw, why was that code disabled in the first place? Is 
> it buggy?

i dunno

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When you are offended at any man's fault, turn to yourself and study your
own failings. Then you will forget your anger. -- Epictetus
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