[FFmpeg-devel] aac: Use the MDCT scaling rather than scale factor offset hacks

Robert Swain robert.swain
Tue Oct 13 20:59:28 CEST 2009


2009/10/9 Alex Converse <alex.converse at gmail.com>:
> On Fri, Oct 9, 2009 at 10:03 AM, Robert Swain <robert.swain at gmail.com> wrote:
>> 2009/10/8 Alex Converse <alex.converse at gmail.com>:
>>> On Wed, Oct 7, 2009 at 4:10 PM, Alex Converse <alex.converse at gmail.com> wrote:
>>>> This patch also folds the minus sign in there.
>>>
>>> Update for r20192.
>>
>> Looks OK to me. Does this improve performance noticably? I wonder if
>> we can reduce the size of ff_aac_pow2sf_tab[] if the encoder doesn't
>> use all of it.
>
> The only noticeable performance increases is in the unloved main
> profile. Performance remains the same for LC (including IS and PNS
> streams).

Makes sense. If you want to do it, you can apply this independently of
the other patches in the set.

> Currently the encoder uses the outlying values in that table but I
> intend on fixing that next.

OK, well once done, feel free to remove cruft from the table.

Regards,
Rob



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