[FFmpeg-devel] [PATCH 0/2] Fix strict aliasing violations in AAC and AC3 parsers
Mon Dec 15 10:35:44 CET 2008
M?ns Rullg?rd <mans at mansr.com> writes:
> "Jason Garrett-Glaser" <darkshikari at gmail.com> writes:
>>> am i interperting this correctly, that the code is hugely faster with
>>> and iam of course in favor of the faster variant for h264.c
>> Yes, but it makes absolutely no sense why it would be faster--the
>> oprofile says even the asm functions are faster which of course makes
>> no sense at all.
>> Others in #ffmpeg-devel have reported small speed increases or
>> decreases, but nothing like what I posted.
> Changes in decoding time after adding -fno-strict-aliasing on ARM:
> H.264 -2.4%
> MPEG4 +0.14%
> MPEG2 -2.3%
> Vorbis +0.08%
> Flac +3.6%
> MP3 +2.6%
> AC3 +0.83%
> DTS +0.81%
BTW, that was with codesourcery gcc 4.2.1.
> I will test with Jason's sample on Core2 and see if I get anything
> resembling his results.
Tested on Core2, and I get no such numbers:
vanilla 203.7867 s
-fno-strict-aliasing 204.2257 s
This was with gcc 4.2.4.
mans at mansr.com
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