[FFmpeg-devel] [PATCH 1/2] avcodec/x86: move simple_idct to external assembly

[James Darnley]

On 2017-05-29 23:26, Michael Niedermayer wrote:
> On Mon, May 29, 2017 at 09:40:49PM +0200, James Darnley wrote:
>> On 2017-05-29 16:51, James Darnley wrote:
>>> ---
>>> Changes:
>>>  - Changed type of d40000 constant to dwords because it gets used as dwords.
>>>  - Changed or removed HAVE_MMX_INLINE preprocessor guards.
>>>  - Added note about conversion from inline.
>>>  - New file no longer has "2" suffix.
>>>  - Whitespace (indentation and alignment).
>>>
>>>  libavcodec/tests/x86/dct.c     |   2 +-
>>>  libavcodec/x86/Makefile        |   4 +-
>>>  libavcodec/x86/idctdsp_init.c  |   4 -
>>>  libavcodec/x86/simple_idct.asm | 889 +++++++++++++++++++++++++++++++++++++++
>>>  libavcodec/x86/simple_idct.c   | 929 -----------------------------------------
>>>  5 files changed, 892 insertions(+), 936 deletions(-)
>>>  create mode 100644 libavcodec/x86/simple_idct.asm
>>>  delete mode 100644 libavcodec/x86/simple_idct.c
>>
>> Ronald queried on IRC about the performance.  The libavcodec/tests/dct
>> utility reports these numbers
>>
>> Yorkfield:
>>  - inline:   IDCT SIMPLE-MMX: 15715.9 kdct/s
>>  - external: IDCT SIMPLE-MMX: 15699.9 kdct/s
>>
>> Skylake-U:
>>  - inline:   IDCT SIMPLE-MMX: 11193.3 kdct/s
>>  - external: IDCT SIMPLE-MMX: 11189.7 kdct/s
> 
> Its better to benchmark by decoding some videos as the sparsness of
> the coeffs affects speed

Ah, quite true.

Decoding a large HD sample for many runs stays close around 220fps and
187s run time before and after the change.

I will push shortly.