[FFmpeg-cvslog] ac3enc: use MUL64() to multiply fixed-point coefficients

[Måns Rullgård]

Justin Ruggles <justin.ruggles at gmail.com> writes:

> On 03/09/2011 12:30 PM, Michael Niedermayer wrote:
>
>> On Tue, Mar 08, 2011 at 06:18:44PM -0500, Justin Ruggles wrote:
>>> On 03/08/2011 02:01 PM, Justin Ruggles wrote:
>>>
>>>> ffmpeg | branch: master | Justin Ruggles <justin.ruggles at gmail.com> | Tue Mar  8 13:18:55 2011 -0500| [67fc32ac6197a7fe265795d0bf60bf704464394e] | committer: Michael Niedermayer
>>>>
>>>> ac3enc: use MUL64() to multiply fixed-point coefficients
>>>>
>>>> Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
>>>>
>>>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=67fc32ac6197a7fe265795d0bf60bf704464394e
>>>> ---
>>>>
>>>>  libavcodec/ac3enc.c       |    8 ++++----
>>>>  libavcodec/ac3enc_fixed.h |    2 ++
>>>>  libavcodec/ac3enc_float.h |    2 ++
>>>>  3 files changed, 8 insertions(+), 4 deletions(-)
>>>>
>>>
>>>
>>> This change is unnecessary and can be safely reverted.
>> 
>> i thought it improves speed on some cpus where MUL64 is optimized ?
>> but i can revert if you want me to
>
> Well, I wasn't thinking of that case.  The original purpose of the patch
> was only because it was necessary in earlier versions of my patch set
> where I was moving the rematrixing strategy decision to after the
> coefficient scaling.
>
> It might very well be faster though.  MAC64() would be another option.
> I'll work on that and send a separate patch.

The inputs here are 16-bit so none of the existing macros are right.

-- 
M?ns Rullg?rd
mans at mansr.com