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

[Michael Niedermayer]

On Wed, Mar 09, 2011 at 06:07:51PM +0000, M?ns Rullg?rd wrote:
> 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.

The output of the MDCT should be more than 16bit.
If thats not the case theres some quality that could be gained, at least at
the high bitrate side IMHO

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If you think the mosad wants you dead since a long time then you are either
wrong or dead since a long time.
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