[FFmpeg-devel] [PATCH] Patch cleanup for MPEG 1 & 2 optimizations

Michael Niedermayer michaelni
Wed Apr 16 23:23:00 CEST 2008

On Wed, Apr 16, 2008 at 10:31:34PM +0200, Keiji Costantini wrote:
> Benoit Fouet ha scritto:
>> Hi,
>> strites wrote:
>>> diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
>>> index c128949..ba0e73b 100644
>>> --- a/libavcodec/mpegvideo.c
>>> +++ b/libavcodec/mpegvideo.c
>>> @@ -1978,6 +1978,7 @@ skip_idct:
>>>      }
>>>  }
>>> +av_always_inline
>>>  void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64]){
>> what exactly is the point of this hunk ??
> Ups...
> I corrected that and got actually a speed gain.

Your patches still contain the typo jeff pointed out, also i think
they are identical to jeffs variant after the typo is fixed.

The question i have is the code with your patches applied as fast as
if is_mpeg12 would be hardcoded to 1 ?

Jeffs benchmarks indicated that there still was a speed difference left
but it could be as well random variation. If there is still a difference
left i would like to know what is causing this difference. Is it just
the overhead for the extra if() and call or is there more?

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Good people do not need laws to tell them to act responsibly, while bad
people will find a way around the laws. -- Plato
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